The Effects ofUV Light and Weather

onPlastics and Elastomers

Second Edition

Liesl K. Massey

Copyright © 2007 by William Andrew, Inc. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the Publisher. Plastics Design Library and its logo are owned by William Andrew, Inc. Library of Congress Cataloging-in-Publication Data Massey, Liesl K. The effects of UV light and weather on plastics and elastomers / Liesl K. Massey. -- 2nd ed. p. cm. Includes bibliographical references and index. ISBN-13: 978-0-8155-1525-8 (978-0-8155) ISBN-10: 0-8155-1525-1 (0-8155) 1. Plastics--Effect of radiation on. 2. Elastomers--Effect of radiation on. I. Title. TA455.P5M34355 2007 620.1'9232--dc22 2006018850 Printed in the United States of America This book is printed on acid-free paper. 10 9 8 7 6 5 4 3 2 1 Published by: William Andrew Publishing 13 Eaton Avenue Norwich, NY 13815 1-800-932-7045 www.williamandrew.com

NOTICE To the best of our knowledge the information in this publication is accurate; however the Publisher does not assume any responsibility or liability for the accuracy or completeness of, or consequences arising from, such information. This book is intended for informational purposes only. Mention of trade names or commercial products does not constitute endorsement or recommendation for their use by the Publisher. Final determination of the suitability of any information or product for any use, and the manner of that use, is the sole responsibility of the user. Anyone intending to rely upon any recommendation of materials or procedures mentioned in this publication should be independently satisfied as to such suitability, and must meet all applicable safety and health standards.

“To nourish children and raise them against odds is in any time, any place, more valuable than to fixbolts in cars or design nuclear weapons.” Marilyn French

I dedicate this book to the wonderful man who has allowed me to realize this to be true.

William Andrew Publishing

Sina Ebnesajjad, Editor in Chief (External Scientific Advisor)

Table of Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

List of Graphs and Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1How to Use This Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Weatherability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Weather Defined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Variations in Natural Weathering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Testing for Weatherability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Elements of Weather . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Wavelength Regions of UV Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Moisture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Radiation and Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Radiation and Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Reducing the Effect of Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Surface Temperature and Thermal Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Material Properties Post-Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4UV Additives and Stabilizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

UV Absorbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Hindered Amine Light Stabilizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Antioxidants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6UV Inhibitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Test Environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Indoor and Interior Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Outdoor Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Accelerated Outdoor Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Conventional Aging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Conventional Aging with Spray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Humidity Variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Solar Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Sample Mounting Direction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Artificial Accelerated Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Conditions for Reproducing Natural Weathering Stresses

in the Laboratory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Xenon Arc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Fluorescent or QUV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Carbon Arc or Fadeometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Test Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Notes on Variability in Testing and Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Color Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

vi The Effects of UV Light and Weather on Plastics and Elastomers

Thermoplastics

ABS

Acrylonitrile-Butadiene-Styrene—Chapter 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Stabilization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Acrylonitrile-Styrene-Acrylate/Acrylonitrile-Butadiene-StyreneCapstock—Chapter 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Acetal

Acetal—Chapter 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Weathering Properties: General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Weathering Properties: Colored Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Weathering Properties: Unpigmented Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Weathering Properties: Elevated Air Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Acrylonitrile-Styrene-Acrylate

Acrylonitrile-Styrene-Acrylate—Chapter 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Degree of Discoloration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Thermal Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Acrylic

Acrylic and Acrylic Copolymer—Chapter 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Acrylic and Polyvinyl Chloride Coextrusion—Chapter 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . 65Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Cellulosic Plastic

Cellulose Acetate Butyrate—Chapter 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Color Retention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Table of Contents vii

Fluoropolymers

Fluoropolymers: Overview—Chapter 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71Fluoropolymer Weathering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Polytetrafluoroethylene (PTFE or TFE)—Chapter 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Fluorinated Ethylene Propylene (FEP)—Chapter 10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Perfluoroalkoxy (PFA and MFA)—Chapter 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Polyvinylidene Fluoride (PVDF)—Chapter 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Polychlorotrifluoroethylene (PCTFE)—Chapter 13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Ethylene-chlorotrifluoroethylene (ECTFE)—Chapter 14 . . . . . . . . . . . . . . . . . . . . . . . . . . . 91Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Ethylene-tetrafluoroethylene (ETFE)—Chapter 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Polyvinyl Fluoride (PVF)—Chapter 16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

Ionomer

Ionomer—Chapter 17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

Polyphenylene Oxide

Polyphenylene Oxide—Chapter 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109Weathering Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

Nylon

Nylon: Overview—Chapter 19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115Weathering Properties: General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115Weathering Properties: UV Stabilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115Weathering Properties: Colored Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

viii The Effects of UV Light and Weather on Plastics and Elastomers

Nylon 6—Chapter 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

Nylon 12—Chapter 21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

Nylon with Glass Fiber—Chapter 22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

Nylon 66—Chapter 23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135Weathering Properties: Colored Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

Nylon 6,6T—Chapter 24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

Nylon MXD6—Chapter 25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

Polyarylamide—Chapter 26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

Polycarbonate

Polycarbonate—Chapter 27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147Light Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148Weathering Properties: UV Stabilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

Polycarbonate Blends—Chapter 28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159Weathering Properties: Stabilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

Polyester

Polybutylene Terephthalate—Chapter 29 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161Weathering Properties: Stabilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

Polyethylene Terephthalate—Chapter 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168

Table of Contents ix

Liquid Crystal Polymers—Chapter 31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174

Polyarylate—Chapter 32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

Polyimide

Polyimide—Chapter 33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177Weathering Properties: General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177Weathering Properties: Outer Space and Nuclear Environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

Polyamideimide—Chapter 34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181

Polyetherimide—Chapter 35 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

Polyketone

Polyetheretherketone (PEEK)—Chapter 36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

Polyolefin

Polyethylene: Overview—Chapter 37 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187Weathering Properties: General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187Polyethylene Films . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187Weathering Properties: Color Pigments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188Weathering Properties: UV Stabilizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

Low Density Polyethylene—Chapter 38 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193

High Density Polyethylene—Chapter 39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195Weathering Properties: Colored Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

Carbon Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195White Pigments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195Yellow Pigments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195Red Pigments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196Orange Pigments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196Blue and Green Pigments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197

x The Effects of UV Light and Weather on Plastics and Elastomers

Pigment Dispersion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197Part Thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197

Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198

Ultrahigh Molecular Weight Polyethylene—Chapter 40 . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

Polyethylene Copolymers—Chapter 41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214

Polypropylene—Chapter 42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215Weathering Properties: Stabilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

Polymethylpentene—Chapter 43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223

Polyphenylene Sulfide

Polyphenylene Sulfide—Chapter 44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225

Polystyrene

General Purpose Polystyrene—Chapter 45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227

High Impact Polystyrene—Chapter 46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232

Polysulfone

Polysulfone—Chapter 47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239

Polyethersulfone—Chapter 48 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

Table of Contents xi

Styrene Acrylonitrile Copolymer

Styrene-Acrylonitrile Copolymer—Chapter 49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244

Styrene Butadiene Copolymer

Styrene-Butadiene Copolymer—Chapter 50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247Indoor UV Light Resistance and Indirect Sunlight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247

Vinyl Resin

Polyvinyl Chloride—Chapter 51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249

Thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249Plasticizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249

Additional Plasticizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250Stabilizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251Pigments and Colorants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251Yellowing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252

Weathering Properties: Stabilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252

Chlorinated Polyvinyl Chloride—Chapter 52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255

Thermoplastic Blends/Alloys

ABS Vinyl Resin Alloy

ABS Polyvinyl Chloride Alloy—Chapter 53 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257

Acrylic (PMMA) Polyvinyl Alloy—Chapter 54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

Polycarbonate ABS Alloy—Chapter 55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261

Biodegradable Thermoplastic Alloys

Biodegradable Polyethylene Films

Biodegradable Polyethylene Films—Chapter 56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263

xii The Effects of UV Light and Weather on Plastics and Elastomers

Degradation Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264

Starch Synthetic Resin Alloy—Chapter 57 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269Biodegradability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269

Thermosets

Polyester

Thermoset Polyester—Chapter 58 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271Polyester Powder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271Urethane Polyesters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271Weathering Properties: UV Stabilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272

Polyurethane

Polyurethane Reaction Injection Molding System—Chapter 59 . . . . . . . . . . . . . . . . . . . 273Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274

Thermoplastic Elastomers

Thermoplastic Elastomers

Thermoplastic Elastomers: Overview—Chapter 60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279

Chlorinate Polyethylene Elastomer—Chapter 61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281

Olefinic Thermoplastic Elastomer—Chapter 62 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283Outdoor Accelerated Exposure Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285

Polyester Thermoplastic Elastomer—Chapter 63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301Weathering Properties: Color Pigments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302

Polystyrene-Butadiene-Styrene Thermoplastic—Chapter 64 . . . . . . . . . . . . . . . . . . . . . . 311Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311

Styrenic Thermoplastic Elastomer—Chapter 65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313

Table of Contents xiii

Weathering Properties: Stabilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314

Urethane Thermoplastic Elastomer—Chapter 66 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315Weathering Properties: UV Stabilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317

Nitrile Thermoplastic Elastomers—Chapter 67. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324

Thermosetting Elastomers (Rubbers)

Thermoset Elastomers or Rubbers

Thermoset Elastomers or Rubbers: Overview—Chapter 68 . . . . . . . . . . . . . . . . . . . . . . . 325

Butyl Rubber, Bromobutyl Rubber, and Chlorobutyl Rubber—Chapter 69 . . . . . . . . 327Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327Weathering Properties: Ozone Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327

Chlorosulfonated Polyethylene Rubber—Chapter 70 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329Weathering Properties: Color Pigments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329Weathering Properties: Curing Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330Weathering Properties: Fillers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331Weathering Properties: Plasticizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332

Ethylene-Propylene Copolymer—Chapter 71 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343

Ethylene-Propylene Diene Methylene Terpolymer—Chapter 72 . . . . . . . . . . . . . . . . . . . 345UV Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345Outdoor Weather Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345Accelerated Outdoor Weathering Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346Accelerated Artificial Weathering Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347Effect of Carbon Black on Weatherability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347Effect of Color Pigments on Weatherability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347

Effective UV Screening Agents in Mineral-Filled Vulcanizates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348Effect of Curing Systems on Weatherability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348Effect of Plasticizers on Weatherability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348Ozone Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348

Neoprene Rubber—Chapter 73 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374

xiv The Effects of UV Light and Weather on Plastics and Elastomers

Polybutadiene—Chapter 74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384

Polyisoprene Rubber—Chapter 75. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386

Polyurethane—Chapter 76 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391Weathering Properties: Stabilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392

Silicone Rubber—Chapter 77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393Weathering Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393Weathering Properties by Material Supplier Trade Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393

Fluoropolymers in Coating Applications—Appendix 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395Architectural Fabrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395

Fabric Base Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395Fabric Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395Fabric Top Finishes or Topcoats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395

Weathering Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396

Coil Coatings—Appendix 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399Comparative Properties and Performance Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399

Coil Coating Topcoats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399

Glossary of Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445Trade Name Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453Plastics Design Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 455

Preface

Welcome to the Second Edition of The Effects ofUV Light and Weather on Plastics and Elastomers,an extensive compilation on how the elements ofweathering affect the properties and characteristicsof plastics and elastomers. Designed as a referencehandbook, this edition presents data in a format thatallows the user to easily compare and contrast per-formance characteristics between different polymerfamilies and, where possible, between the productsavailable within a material family itself. Informationwas compiled from many different sources: materialmanufacturers, technical journals, and papers, etc.Extensive and detailed references are provided tofurther research materials and material applications.

Amajor contributing factor to the outdoor weath-ering (degradation) of polymers is UV light. Temper-ature, moisture, and pollutants combine with the UVlight and degrade polymers by different mechanisms.Design and application engineers and scientists needto know how a material will perform under variousconditions. The level of deterioration expected andaccepted varies by application and end use. In manyinstances, the application for which the material isintended has a group or society that has providedstandardized tests for evaluating the materials (e.g.,the Society of Automotive Engineers provides theSAE Test Methods. ASTM International publishesextensive weathering test methods often referencedby users and manufacturers of outdoor-orientedmaterials.

The introductory chapter is designed to providebasic information on the components of weather-ing, material properties affected by weathering, anda review of the most common testing environments.Brief discussions of weathering stabilizers as well ascolor stability are included.

The body of this edition presents discussion andresults of weathering and outdoor exposure testing.Each of the seventy-seven chapters represents a spe-cific material family, and the information relating to

that material is provided in textual, graphical, andtabular form. Textual information provides discus-sion of the material’s susceptibility or immunity toweathering or its components as well as discussionof test results. Graphical and tabular representationof data allows the user to quantitatively understandthe material’s performance under specific criteria ormultiple test methods.

Information is included for as many materials,tests, and conditions as possible. Even where detailedmetadata are not available, general information isprovided. It should be noted that the content ofthe material chapters is representative rather thanall-inclusive. That is, a polymer’s performance ispresented in as much detail as possible from thesources available. All manufacturers of all outdoormaterials are not included due to obvious spacelimitations.

At the end of this book extensive references areprovided in the event that further research and studyare warranted. It is my hope that this reference hand-book is the first book to which a designer, engineer, orscientist refers when looking for general weatheringproperties and comparing properties between fami-lies of polymers. However, this reference handbookshould not serve as a substitute for actual testing todetermine the suitability of a material for use. Pleasecontact the manufacturers of these materials for thelatest and most complete material and performanceinformation.

A special word of thanks to those who haveallowed their information and test data to be includedin this book. Every effort was made to present theinformation in its original context. As always, yourfeedback as a reader and user of this information isappreciated and encouraged.

Liesl K. Massey 2006

List of Graphs and Tables

List of Graphs

1-1 Changes in Material Characteristics due to Photo-Oxidation of ABS . . . . . . . . . . . . . . . . . 161-2 Outdoor Weathering Exposure Time vs.Yellowness Index of ABS . . . . . . . . . . . . . . . . . . . . 161-3 Arizona Outdoor Weathering Exposure Time vs. Dart Drop Impact Strength of ABS . . . 171-4 Arizona Outdoor Weathering Exposure Time vs. Elongation of ABS . . . . . . . . . . . . . . . . . . 171-5 Arizona Outdoor Weathering Exposure Time vs. Tensile Strength at Yield of ABS . . . . . . 181-6 Arizona Outdoor Weathering Exposure Time vs. �E Color Change of ABS . . . . . . . . . . . 181-7 Arizona, Florida, and Ohio Outdoor Weathering Exposure Time vs. Dart Drop Impact

Strength of ABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191-8 Florida Outdoor Weathering Exposure Time vs. Dart Drop Impact Strength of ABS . . . . 191-9 Florida Outdoor Weathering Exposure Time vs. Drop Weight Impact of ABS . . . . . . . . . . 201-10 Florida Outdoor Weathering Exposure Time vs. �E Color Change of ABS . . . . . . . . . . . . 201-11 Florida Weathering Exposure Time vs. Chip Impact Strength of ABS (White Rovel

Capstock and Acrylic Capstock) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211-12 Florida Weathering Exposure Time vs. Chip Impact Strength of ABS (Natural Resin) . . . 211-13 Ohio Outdoor Weathering Exposure Time vs. �E Color Change of ABS . . . . . . . . . . . . . . 221-14 Ohio Outdoor Weathering Exposure Time vs. Dart Drop Impact Strength of ABS . . . . . . 221-15 Okinawa, Japan, Outdoor Weathering Exposure Time vs. �E Color Change of ABS . . . 231-16 Okinawa, Japan, Outdoor Weathering Exposure Time vs. Dynstat Impact Strength

Retained of ABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231-17 Okinawa, Japan, Outdoor Weathering Exposure Time vs. Elongation at Break

Retained of ABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241-18 Okinawa, Japan, Outdoor Weathering Exposure Time vs. Gloss Retained of ABS . . . . . 241-19 West Virginia Outdoor Weathering Exposure Time vs. Falling Dart Impact of

ABS at −40◦C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251-20 West Virginia Outdoor Weathering Exposure Time vs. Falling Dart Impact of ABS at

23◦C, −25◦C, and −40◦C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251-21 West Virginia Outdoor Weathering Exposure Time vs. Falling Dart Impact of

ABS at 23◦C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261-22 West Virginia Outdoor Weathering Exposure Time vs. Flexural Modulus Retained

of ABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261-23 West Virginia Outdoor Weathering Exposure Time vs. Flexural Strength of ABS

at −40◦C and 23◦C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271-24 West Virginia Outdoor Weathering Exposure Time vs. Flexural Strength Retained

of ABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271-25 West Virginia Outdoor Weathering Exposure Time vs. Izod Impact Strength Retained

of ABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281-26 West Virginia Outdoor Weathering Exposure Time vs. Tensile Strength Retained

of ABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281-27 Sunshine Weatherometer Exposure Time vs. Dynstat Impact Strength

Retained of ABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

xviii The Effects of UV Light and Weather on Plastics and Elastomers

1-28 Sunshine Weatherometer Exposure Time vs. Elongation at BreakRetained of ABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

1-29 Sunshine Weatherometer Exposure Time vs. Gloss Retained of ABS . . . . . . . . . . . . . . . . 301-30 Weatherometer Exposure Time vs. Impact Strength of ABS . . . . . . . . . . . . . . . . . . . . . . . . . 301-31 Xenotest 1200 Exposure Time vs. Impact Strength of ABS . . . . . . . . . . . . . . . . . . . . . . . . . . 311-32 Accelerated Indoor UV Exposure Time vs. �E Color Change of ABS . . . . . . . . . . . . . . . . 311-33 Yellowness Index of UVA- and HALS-Stabilized ABS after Outdoor Weathering in

Switzerland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322-1 Color Change, �E, after Arizona, Florida, and New York Outdoor Weathering of GE

Plastics Cycolac®/Geloy® Resin Systems Compared to PVC . . . . . . . . . . . . . . . . . . . . . . . . 333-1 Relative Tensile Strength after Accelerated Interior Weathering According to SAE

J1885 for Dupont Delrin® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403-2 Relative Gloss after Accelerated Interior Weathering According to SAE J1885 for

DuPont Delrin® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403-3 Changes in Mechanical Properties after Light Exposure of Ticona Celcon® UV90Z . . . . 413-4 Outdoor Exposure Time vs. Impact Strength Retained of BASF Ultraform® N 2320

and Ultraform® N 2325 U Acetal Copolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413-5 New Jersey and Arizona Outdoor Exposure Time vs.Tensile Impact Strength of Ticona

Celcon® M90 and UV90 Acetal Copolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423-6 New Jersey and Arizona Outdoor ExposureTime vs.Tensile Strength atYield ofTicona

Celcon® M90 Acetal Copolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423-7 New Jersey Outdoor Exposure Time vs. Tensile Strength at Yield of Ticona Celcon®

GC25 A Acetal Copolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433-8 QUV Exposure Time vs. �E Color Change of Ticona Celcon® Acetal Copolymer . . . . . . 433-9 Sunshine Weatherometer Exposure Time vs. Elongation Retained of Mitsubishi

Iupital® F20 Acetal Copolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443-10 Sunshine Weatherometer Exposure Time vs. Tensile Strength Retained of Mitsubishi

Iupital® F20 Acetal Copolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443-11 Xenon Arc Weatherometer Exposure Time vs. Relative Gloss of BASF Ultraform®

N Acetal Copolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 454-1 Yellowness Index after Outdoor Exposure for BASF Luran® S 797 and Luran® S 776

ASA Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 494-2 Color Change, �E, after Outdoor Weathering in Okinawa, Japan, for Mitsubishi

Rayon® ASA Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504-3 Impact Strength Retained after Outdoor Weathering in Okinawa, Japan, for Mitsubishi

Rayon® ASA Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504-4 Elongation at Break Retained after Outdoor Weathering in Okinawa, Japan, for

Mitsubishi Rayon® ASA Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514-5 Gloss Retained after Outdoor Weathering in Okinawa, Japan, for Mitsubishi Rayon®

ASA Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514-6 Impact Strength Retained after Sunshine Weatherometer Exposure for Mitsubishi

Rayon® T110 and T120 ASA Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 524-7 Impact Strength Retained after Sunshine Weatherometer Exposure for Mitsubishi

Rayon® ASA Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 524-8 Elongation at Break Retained after Sunshine Weatherometer Exposure for Mitsubishi

Rayon® ASA Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 534-9 Gloss Retained after Sunshine Weatherometer Exposure for Mitsubishi Rayon® T115

and T110 ASA Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 534-10 Gloss Retained after Sunshine Weatherometer Exposure for Mitsubishi Rayon® ASA

Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

List of Graphs and Tables xix

4-11 Impact Strength after Weatherometer Exposure for BASF Luran® S ASA Polymer atDifferent Test Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

4-12 Impact Strength after Xenotest 1200 Exposure for BASF Luran® S 797 and Luran® S776 ASA Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

4-13 Yellowness Index of ABS, Luran® S, and Blends after Exposure to Sunshine . . . . . . . . . . 554-14 Penetration Energy after Exposure to Sunshine on 2-mm Thick Disks of Luran® S

778 T, Luran® S 778 T UV, Luran® S KR 2861/1 C, ABS-UV, and PC+ABS . . . . . . . . . . . 565-1 LightTransmission for Acrylic, Cyrolon® UVP Polycarbonate Sheet, and Polycarbonate

after Weathering Exposure as per ASTM D1003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 595-2 Yellowness Index for Acrylic, Cyrolon® UVP Polycarbonate Sheet, and Polycarbonate

after Weathering Exposure as per ASTM D1925 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 595-3 Percentage Haze for Acrylic, Cyrolon® UVP Polycarbonate Sheet, and Polycarbonate

after Weathering Exposure as per ASTM D1003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 605-4 Luminous Transmittance, Haze, Yellowness Index, and Surface Gloss of Plexiglas®

V825 after Florida and Arizona Weathering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 615-5 Luminous Transmittance, Haze, Yellowness Index, and Surface Gloss of Plexiglas®

DR101 after Florida and Arizona Weathering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625-6 Luminous Transmittance, Haze, Yellowness Index, and Surface Gloss of Plexiglas®

V920 after Florida and Arizona Weathering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 635-7 Color Change, �E, after Atlas Weatherometer Exposure of Novacor NAS® 30, NAS®

36, Zylar® 533, and Other Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 637-1 Tensile Strength at Break after Arizona Weathering for Eastman Tenite®

Butyrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 687-2 Elongation at Break after Arizona Weathering for Eastman Tenite® Butyrate . . . . . . . . . . 687-3 Impact Strength after Weathering for Eastman Tenite® Butyrate . . . . . . . . . . . . . . . . . . . . . 698-1 Mechanical Properties of PVDF, ETFE, and PVF Films after South Florida

Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7110-1 Retention of Tensile Strength and Percentage Elongation after Outdoor Exposure for

DuPont FEP Film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7711-1 Color Change, �E, after Carbon Arc Weatherometer Accelerated Weathering

(Dew Cycle) for PFA and MFA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7911-2 Tensile Strength Retention after Carbon Arc Weatherometer Accelerated Weathering

(Dew Cycle) for PFA and MFA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8011-3 Elongation Retention after Carbon Arc Weatherometer Accelerated Weathering

(Dew Cycle) for PFA and MFA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8012-1 Retention ofTensile Strength and Elongation after Miami, Florida, Outdoor Weathering

Exposure (45◦ Angle South) for PVDF Film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8412-2 Color Change, �E, after Miami, Florida, Outdoor Weathering Exposure (45◦ Angle

South) for Solvay Solexis Hylar® 5000 PVDF Pigmented Coatings . . . . . . . . . . . . . . . . . . . 8412-3 Gloss Retention after Miami, Florida, OutdoorWeathering Exposure (45◦ Angle South)

for Solvay Solexis Hylar® 5000 PVDF Pigmented Coatings . . . . . . . . . . . . . . . . . . . . . . . . . 8512-4 Chalk Rating after Florida Exposure (45◦ Angle South) for Commercial White Paints . . . 8512-5 Gloss Retention after Florida Exposure (45◦ Angle South) for Commercial

White Paints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8613-1 Elongation Retained in the Machine Direction after Weatherometer Exposure of

Honeywell Aclar® 22A and Aclar® 33C PCTFE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8713-2 Elongation Retained in the Transverse Direction after Weatherometer Exposure of

Honeywell Aclar® 22A and Aclar® 33C PCTFE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8813-3 Tensile Strength Retained in the Machine Direction after Weatherometer Exposure of

Honeywell Aclar® 22A and Aclar® 33C PCTFE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

xx The Effects of UV Light and Weather on Plastics and Elastomers

13-4 Tensile Strength Retained in the Transverse Direction after Weatherometer Exposureof Honeywell Aclar® 22A and Aclar® 33C PCTFE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

14-1 Retention ofTensile Strength and Elongation after Miami, Florida, Outdoor WeatheringExposure (45◦ Angle South) for Solvay Solexis Halar® ECTFE Film . . . . . . . . . . . . . . . . . . 92

14-2 Retention of Tensile Strength and Elongation after QUV Accelerated WeatheringExposure, UVB-313, for Solvay Solexis Halar® ECTFE Film . . . . . . . . . . . . . . . . . . . . . . . . 92

14-3 Color Change, �E, after QUV Accelerated Weathering Exposure, UVB-313, for SolvaySolexis Halar® ECTFE Film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

16-1 Percentage of Initial Properties Retained after South Florida Weathering Exposure atan Angle of 45◦ Facing South for DuPont Tedlar® PVF Film . . . . . . . . . . . . . . . . . . . . . . . . . 98

16-2 Percentage Gloss Retention after South Florida Weathering Exposure at an Angle of45◦ Facing South for DuPont Tedlar® PVF Film and Pigmented Vinyl Film . . . . . . . . . . . . 98

16-3 Average Rate of UV Absorber Degradation in Free-Standing DuPont Tedlar® PVF Filmafter Florida Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

16-4 Color Stability of DuPont Tedlar® PVF Film after Exposure to Atlas Sunshine ArcWeatherometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

16-5 Percentage of Initial Properties Retained after Atlas Sunshine Arc WeatherometerExposure of DuPont Tedlar® PVF Film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

16-6 Typical Color Change Range of a Variety of Pigmented DuPont Tedlar® SP Films afterXenon Arc Exposure as per the SAE J1960 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

16-7 Gloss Retention of Refinish Paint, Gel Coat, and DuPont Tedlar® SP Film after XenonArc Exposure as per the SAE J1960 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

16-8 Gloss Retention of Acrylic Film, ASA/AES Copolymer, and DuPont Tedlar® SP Filmafter Xenon Arc Exposure as per the SAE J1960 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

18-1 Change in Color, �E, after Accelerated Indoor UV Exposure of Modified PPO . . . . . . . . 11018-2 Dart Drop Impact Strength after Arizona Outdoor Weathering Exposure of

Modified PPO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11118-3 Percentage Elongation after Arizona Outdoor Weathering Exposure of

Modified PPO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11118-4 Tensile Strength after Arizona Outdoor Weathering Exposure of Modified PPO . . . . . . . . 11218-5 Change in Color, �E, after Arizona Outdoor Weathering Exposure of Modified PPO . . . 11218-6 Change in Color, �E, after Ohio Outdoor Weathering Exposure of Modified PPO . . . . . 11318-7 Dart Drop Impact Strength after Ohio Outdoor Weathering Exposure of

Modified PPO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11320-1 Elongation at Break after Outdoor Exposure for Ube Ube® Nylon 6 . . . . . . . . . . . . . . . . . . 11920-2 Flexural Modulus after Outdoor Exposure for Ube Ube® Nylon 6 . . . . . . . . . . . . . . . . . . . . 12020-3 Notched Izod Impact Strength after Outdoor Exposure for Ube Ube® Nylon 6 . . . . . . . . . 12020-4 Tensile Strength after Outdoor Exposure for Ube Ube® Nylon 6 . . . . . . . . . . . . . . . . . . . . . 12120-5 Flexural Strength at Break after Outdoor Exposure in Hiratsuka, Japan, for Nylon 6 . . . 12120-6 Flexural Modulus after Outdoor Exposure in Hiratsuka, Japan, for Nylon 6 . . . . . . . . . . . . 12220-7 Notched Izod Impact Strength after Outdoor Exposure in Hiratsuka, Japan,

for Nylon 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12220-8 Weight Change after Outdoor Exposure in Hiratsuka, Japan, for Nylon 6 . . . . . . . . . . . . . 12320-9 Flexural Strength after Outdoor Exposure in Hiratsuka, Japan, for Nylon 6 . . . . . . . . . . . . 12320-10 Tensile Strength after Outdoor Exposure in Hiratsuka, Japan, for Nylon 6 . . . . . . . . . . . . . 12420-11 Elongation after Sunshine Weatherometer Exposure of Nylon 6 . . . . . . . . . . . . . . . . . . . . . 12420-12 Tensile Strength after Sunshine Weatherometer Exposure of Nylon 6 . . . . . . . . . . . . . . . . 12521-1 Change in Color, �E, after Weatherometer Exposure of EMS Grilamid® TR 55, TR 55

LX, TR 90, and TR 90 UV Nylon 12 Compared to Other Polymers . . . . . . . . . . . . . . . . . . . 128

List of Graphs and Tables xxi

21-2 Yellow Index (YI) after Weathering Exposure as per ASTM D1975 for EMS Grilamid®

TR 90, TR 90 UV, TR 55, and TR 55 LX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12821-3 Tensile Impact Strength after Weatherometer Exposure for EMS Grilamid® TR 55,

TR 55 LX, and TR 55 LY Nylon 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12921-4 Tensile Impact Strength after Weatherometer Exposure for EMS Grilamid® TR 90 and

TR 90 UV Compared to Other Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12921-5 Tensile Impact Strength Half-Life after Weathering for EMS Grilamid® TR 90, TR 90

LX, and TR 90 UV Compared to Other Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13021-6 Yield Strength after Weathering Exposure as per ISO 4892-2 for EMS Grilamid® TR 90,

TR 90 UV, TR 55, and TR 55 LX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13021-7 Percentage Retention ofYield Strength after Weathering Exposure as per ISO 4892-2

for EMS Grilamid® TR 90, TR 90 UV, TR 55, and TR 55 LX . . . . . . . . . . . . . . . . . . . . . . . . . 13021-8 Percentage Retention of Elongation at Break after Weathering Exposure as per ISO

4892-2 for EMS Grilamid® TR 90, TR 90 UV, TR 55, and TR 55 LX . . . . . . . . . . . . . . . . . . 13121-9 Percentage Retention of Work to Break after Weathering Exposure as per ISO 4892-2

for EMS Grilamid® TR 90, TR 90 UV, and TR 55 LX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13121-10 Transparency of EMS Grilamid® and EMS Grivory® Compared to Glass and Other

Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13221-11 Transparency in the Visible Spectrum of EMS Grilamid® Compared to Other

Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13225-1 Flexural Modulus after Outdoor Exposure in Hiratsuka, Japan, for Mitsubishi Reny®

MXD6 Nylon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13925-2 Notched Izod Impact Strength after Outdoor Weathering Exposure in Hiratsuka,

Japan, for Mitsubishi Reny® MXD6 Nylon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14025-3 Flexural Strength after Outdoor Weathering Exposure in Hiratsuka, Japan, for

Mitsubishi Reny® MXD6 Nylon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14025-4 Tensile Strength after Outdoor Weathering Exposure in Hiratsuka, Japan, for

Mitsubishi Reny® MXD6 Nylon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14125-5 Elongation (%) after Sunshine Weatherometer Exposure in Hiratsuka, Japan, for

Mitsubishi Reny® MXD6 Nylon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14125-6 Tensile Strength after Sunshine Weatherometer Exposure in Hiratsuka, Japan, for

Mitsubishi Reny® MXD6 Nylon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14226-1 Flexural Strength after Outdoor Exposure in Hiratsuka, Japan, for Solvay IXEF® 1002

and IXEF® 1022 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14426-2 Flexural Modulus after Outdoor Exposure in Hiratsuka, Japan, for Solvay IXEF® 1002

and IXEF® 1022 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14426-3 Notched Izod Impact Strength after Outdoor Exposure in Hiratsuka, Japan, for Solvay

IXEF® 1002 and IXEF® 1022 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14526-4 Weight Change after Outdoor Exposure in Hiratsuka, Japan, for Solvay IXEF® 1002

and IXEF® 1022 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14527-1 Light Transmission of UV-Stabilized GE Plastics Lexan® . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15227-2 Light Transmission of Transparent GE Plastics Lexan® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15227-3 Transmittance through Transparent GE Plastics Lexan® after Florida Outdoor

Exposure as per ASTM G7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15327-4 Yellowness Index after Florida Outdoor Exposure as per ASTM G7 for GE Plastics

Lexan® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15327-5 Haze after Accelerated Outdoor Exposure of Coated and Uncoated Transparent GE

Plastics Lexan® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15327-6 Yellowness Index after Accelerated Outdoor Exposure of Coated and Uncoated

Transparent GE Plastics Lexan® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

xxii The Effects of UV Light and Weather on Plastics and Elastomers

27-7 Yellowness Index after Xenon Arc Weathering for GE Plastics Lexan® . . . . . . . . . . . . . . . . 15427-8 Change in Yellowness Index, �YI, after Whirlygig Accelerated Outdoor Exposure of

GE Plastics Lexan® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15427-9 Yellowness Index after Kentucky Outdoor Weathering for GE Lexan® S-100 Sheet . . . . . 15527-10 Yellowness Index after EMMAQUA Accelerated Arizona Weathering for GE Lexan®

S-100 Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15527-11 Haze (%) after Carbon Arc XW Weathering for GE Lexan® 153 . . . . . . . . . . . . . . . . . . . . . 15627-12 Yellowness Index after Twin Carbon Arc Weathering for GE Lexan® S-100 Sheet . . . . . . 15627-13 Yellowness Index after Outdoor Weathering for PC Natural and UV Stabilized with

Tinuvin® 234 Benzotriazole UV Absorber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15727-14 Gloss (20◦) Retention after Xenon Arc Weathering of Twin Wall PC Sheets (10 mm)

Stabilized with Tinuvin® UV Absorbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15728-1 Color Change, �E, of Pigmented GE Plastics Cycoloy® C1100 PC/ABS after

Accelerated UV Exposure as per SAE J1885 (ATLAS Ci65XW) and DIN75202(XENON450) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

28-2 Color Change, �E, of Pigmented GE Plastics Cycoloy® C1100 PC/ABS afterAccelerated UV Exposure as per SAE J1885 (ATLAS Ci65XW) and DIN75202(XENON450) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

28-3 Color Development after Xenon Arc Weatherometer Exposure of PC/ABS (50/50)Blend with Tinuvin® 234 UV Stabilizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

29-1 Notched Izod Impact Strength after Florida and Arizona Outdoor Weathering forTicona Celanex® PBT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

29-2 Tensile Strength after Florida and Arizona Outdoor Weathering for TiconaCelanex® PBT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

29-3 Flexural Strength at Break after Hiratsuka, Japan, Outdoor Exposure ofPBT Polyester . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

29-4 Flexural Modulus after Hiratsuka, Japan, Outdoor Exposure of PBT Polyester . . . . . . . . 16329-5 Notched Izod Impact Strength after Hiratsuka, Japan, Outdoor Exposure of

PBT Polyester . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16429-6 Weight Change after Hiratsuka, Japan, Outdoor Exposure of PBT Polyester . . . . . . . . . . 16429-7 Tensile Strength Retained after Weatherometer Exposure of Ticona Celanex® PBT . . . . 16529-8 Change in Yellowness Index, �YI, after Light Exposure of PBT Injection-Molded

Plaques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16530-1 Tensile Strength after Sunshine Weatherometer Exposure of PET . . . . . . . . . . . . . . . . . . . 17130-2 Elongation after Sunshine Weatherometer Exposure of PET . . . . . . . . . . . . . . . . . . . . . . . . 17233-1 Ultimate Elongation after Florida Aging of DuPont Kapton® Film . . . . . . . . . . . . . . . . . . . . . 17733-2 Ultimate Elongation after Atlas Weatherometer Exposure of DuPont Kapton® . . . . . . . . . 17833-3 Elongation Retained after Sunshine Weatherometer Exposure for UBE Upilex® R and

UBE Upilex® S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17833-4 Flexural Strength Retained after Sunshine Weatherometer Exposure for UBE

Upimol® R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17933-5 Tensile Strength Retained after Sunshine Weatherometer Exposure for UBE Upilex® R

and UBE Upilex® S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17933-6 Flexural Strength Retained after UV-CON Exposure for UBE Upimol® R . . . . . . . . . . . . . . 18034-1 Elongation after Atlas Sunshine Carbon Arc Weatherometer Exposure for

Torlon® 4203L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18134-2 Tensile Strength after Atlas Sunshine Carbon Arc Weatherometer Exposure for

Torlon® 4203L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18235-1 Tensile Strength after Xenon Arc Weatherometer Exposure of GE Plastics

Ultem® 1000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

List of Graphs and Tables xxiii

37-1 Retention of Elongation after Atlas Weatherometer Exposure of High DensityPolyethylene (HDPE) Plaques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

37-2 Impact Strength Retained after Atlas Weatherometer Exposure of Linear Low DensityPolyethylene (LLDPE) Plaques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

37-3 Kilolangleys of Exposure to Create 50% Tensile Strength Retained after ArizonaOutdoor Exposure of HDPE-Pigmented Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192

37-4 Tensile Strength after Arizona Exposure of 0.96 Density Unstabilized Polyethylenewith Various Pigments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192

39-1 Tensile Strength after Arizona Outdoor Weathering ofYellow Chevron Phillips Marlex®

HDPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20539-2 Tensile Strength after Weatherometer Exposure of Yellow Chevron Phillips Marlex®

HDPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20539-3 Tensile Strength after Weatherometer Exposure of Red Chevron Phillips

Marlex® HDPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20639-4 Tensile Strength after Weatherometer Exposure of Unstabilized Red Chevron Phillips

Marlex® HDPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20639-5 Tensile Strength after Weatherometer Exposure of Orange Chevron Phillips Marlex®

HDPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20739-6 Tensile Strength after Weatherometer Exposure of Blue Chevron Phillips

Marlex® HDPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20739-7 Tensile Strength after Weatherometer Exposure of Chevron Phillips Marlex® HDPE

with 2% Zinc Oxide and 2% TiO2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20839-8 Tensile Strength after Weatherometer Exposure of Chevron Phillips Marlex® HDPE

with Varying Concentrations of TiO2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20839-9 Tensile Strength after Weatherometer Exposure of Chevron Phillips Marlex® HDPE

with 1% TiO2 and UV Stabilizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20939-10 Tensile Strength after Weatherometer Exposure of Chevron Phillips Marlex® HDPE

with Various Degrees of Pigment Dispersion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20942-1 Kilolangleys to 50% Retained Tensile Strength and Days to Embrittlement after 45◦

South Florida and Oven Aging at 120◦C of UV-Stabilized Polypropylene Plaques . . . . . . 22042-2 Surface Roughness after 45◦ South Florida Weathering Exposure of UV-Stabilized

Polypropylene Plaques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22142-3 Color Change, �E, after Accelerated Weathering for UV-Stabilized Polypropylene

Automotive Fibers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22143-1 Izod Impact Strength Retained after Weatherometer Exposure for Mitsui TPX™ RT18

Polymethylpentene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22345-1 Yellowness Index after Atlas Fadeometer Exposure of General Purpose Polystyrene . . . 22945-2 Yellowness Index after Fluorescent Lamp Exposure of BASF Polystyrol® General

Purpose Polystyrene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22946-1 Yellowness Index after Fadeometer Exposure of Dow Styron® Impact and

Flame-Retardand Polystyrene and Dow Styron® Unmodified Polystyrene . . . . . . . . . . . . . 23346-2 Color Change, �E, after Florida Outdoor Exposure of NOVA Chemicals Styrosun®

HIPS and Other Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23446-3 Color Change, �E, after Arizona Outdoor Exposure of NOVA Chemicals Styrosun®

HIPS and Other Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23446-4 Color Change, �E, after Kentucky Outdoor Exposure of NOVA Chemicals Styrosun®

HIPS and Other Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23546-5 Color Change, �E, after Illinois Outdoor Exposure of NOVA Chemicals Styrosun®

HIPS and Other Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235

xxiv The Effects of UV Light and Weather on Plastics and Elastomers

46-6 Impact Property Retention, Energy at Maximum Load, after 3000 hours ofAtlas Weather-Ometers® Exposure for NOVA Chemicals Styrosun® HIPS andOther Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236

46-7 Impact Property Retention, Total Energy, after 3000 hours of Atlas Weather-Ometers®

Exposure for NOVA Chemicals Styrosun® HIPS and Other Materials . . . . . . . . . . . . . . . . . 23646-8 Impact Property Retention, Maximum Load, after 3000 hours of Atlas Weather-

Ometers® Exposure for NOVA Chemicals Styrosun® HIPS and Other Materials . . . . . . . 23746-9 Impact Strength after Xenon Arc Weathering of HIPS as per ISO 4892-2 . . . . . . . . . . . . . 23746-10 Yellowness Index after Xenon Arc Weathering of HIPS as per ISO 4892-2 . . . . . . . . . . . . 23847-1 Tensile Strength after Xenon Arc Weatherometer Exposure of Polysulfone . . . . . . . . . . . . 24048-1 Tensile Strength after Xenon Arc Weatherometer Exposure of PES . . . . . . . . . . . . . . . . . . 24149-1 Yellowness Index after Arizona Outdoor Weathering of Dow Tyril® SAN Copolymer . . . . 24449-2 Yellowness Index after UV-CON Accelerated Weathering Exposure of

SAN Copolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24551-1 Elongation after Xenon Exposure of Various UV Stabilized PVC Formulations . . . . . . . . 25351-2 Elongation Retention after Xenon Exposure of Various UV-Stabilized PVC

Formulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25351-3 Yellowness Index after Xenon Exposure of Various UV-Stabilized PVC Formulations . . . 25452-1 Drop Weight Impact Strength Retained after Florida Outdoor Weathering Exposure of

CPVC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25556-1 Weight Loss of Mater-Bi Biodegradable Film after Burying in Various Soils . . . . . . . . . . . 26556-2 Elongation Retained after Xenon Weatherometer Exposure of Starch-Modified

Low Density Polyethylene (LDPE) Film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26656-3 Elongation Retained after Composing of Starch-Modified LDPE Film . . . . . . . . . . . . . . . . 26656-4 Starch Content Retained after Burial of Ecostar Starch-Modified PE Film . . . . . . . . . . . . . 26758-1 Yellowness Index after Xenon Arc Weathering of Unsaturated Polyester . . . . . . . . . . . . . . 27259-1 Change in color, �b, after Florida Outdoor Weathering Exposure of Recticel

Colo-Fast® Polyurethane RIM System and Aromatic Polyurethane . . . . . . . . . . . . . . . . . . . 27659-2 Gloss Retained after QUV Weathering Exposure of Recticel Colo-Fast® Polyurethane

RIM System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27759-3 Gloss Retained after Sunshine Carbon Arc Weathering Exposure of Recticel

Colo-Fast® Polyurethane RIM System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27759-4 Results of Visual Inspection after EMMAQUA Accelerated Exposure of Recticel

Colo-Fast® Polyurethane RIM System and Several Other Materials . . . . . . . . . . . . . . . . . . 27862-1 Carbonyl Formation after Xenon Arc Weatherometer Exposure of Dow Chemical

Company’s Engage™ Olefinic Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29862-2 Decrease in Molecular Weight after Xenon Arc Weatherometer Exposure of Dow

Chemical Company’s Engage™ Olefinic Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . 29966-1 Elongation after QUV Exposure of Dow Pellethane® 2103-80 AEF Urethane

Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32066-2 Tensile Strength after QUV Exposure of Dow Pellethane® 2103-80 AEF Urethane

Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32066-3 Yellowness Index after QUV Exposure of Dow Pellethane® 2103-80 AEF Urethane

Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32166-4 Yellowness Index after QUV Exposure of BASF Elastollan® 1185A-10 Urethane

Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32166-5 Tensile Strength after Xenon Weatherometer Exposure of BASF Elastollan® 1185A-10

Urethane Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32270-1 Elongation at Break after Delaware Outdoor Exposure for DuPont Elastomers

Hypalon® 20 Chlorosulfonated Polyethylene Rubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341

List of Graphs and Tables xxv

71-1 Carbonyl Formation after Xenon Arc Exposure for Ethylene-Propylene Copolymer . . . . 34371-2 Decrease in Molecular Weight after Xenon Arc Exposure for Ethylene-Propylene

Copolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34472-1 Carbonyl Formation after Xenon Arc Weatherometer Exposure of EPDM

Terpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37272-2 Decrease in Molecular Weight after Xenon Arc Weatherometer Exposure of EPDM

Terpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37276-1 Change in Color, �b, after Florida Outdoor Weathering of Polyurethane . . . . . . . . . . . . . . 392A1-1 Top Finish Thickness after Accelerated Florida Outdoor Exposure Testing for Acrylic,

PVDF, and DuPont Tedlar® PVF Top Finishes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397A1-2 Color Change, �E, after Accelerated Florida Outdoor Exposure Testing for Acrylic,

PVDF, and DuPont Tedlar® PVF Top Finishes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397A1-3 Gloss Change, 60◦ Gloss, after Accelerated Florida Outdoor Exposure Testing for

Acrylic, PVDF, and DuPont Tedlar® PVF Top Finishes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398

List of Tables

1-1 Outdoor Weathering of White ABS in Florida . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141-2 Outdoor Weathering of ABS in Ludwigshafen, Germany . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141-3 Accelerated Indoor Exposure of GE Plastics Cycolac® VW300 ABS by HPUV . . . . . . . . 151-4 Accelerated Indoor Exposure of GE Plastics Cycolac® KJB ABS to

Fluorescent Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153-1 Color Differences, �E, after Light Exposure for Pigmented Ticona Celcon® UV90Z

(GM and Ford Automotive Colors) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373-2 Color Differences, �E, after Light Exposure for Pigmented Ticona Celcon® UV90Z . . . . 373-3 Color Differences, �E, after Light Exposure for Unpigmented Ticona

Celcon® M90UV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383-4 Color Differences, �E, after Florida Weathering for Ticona Hostaform® Materials . . . . . . 383-5 Color Differences, �E, after Xenotest 1200 for Ticona Hostaform® C 9021 LS Blue

80/4065 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383-6 Tensile Strength and Elongation after Arizona Weathering Exposure for DuPont

Delrin® 507 BK601 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393-7 Tensile Strength and Elongation after Michigan Weathering Exposure for DuPont

Delrin® 507 BK601 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394-1 Color Properties after Florida (45◦ South Facing) Outdoor Exposure for Pigmented

GE Plastics Geloy® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 484-2 Long-Term Material Performance for GE Plastics Geloy® . . . . . . . . . . . . . . . . . . . . . . . . . . . 484-3 Yellowness Index after Outdoor Weathering in Ludwigshafen, Germany, for BASF

Luran® S 776 S ASA Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 495-1 Cyro Acrylite® GP F Acrylic Sheet after Xenon Arc Accelerated Weathering . . . . . . . . . . 585-2 Cyro Acrylite® GP FL Acrylic Sheet after Xenon Arc Accelerated Weathering . . . . . . . . . 585-3 Cyro Acrylite® GP FLW Acrylic Sheet after Xenon Arc Accelerated Weathering . . . . . . . 589-1 Mechanical Properties of PTFE Film after South Florida Exposure . . . . . . . . . . . . . . . . . . 7310-1 Mechanical Properties after 20-Year South Florida Exposure for Two Thicknesses of

FEP Film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7510-2 Tensile Strength and Break Elongation after 20-Year South Florida Exposure for Two

Thicknesses of FEP Film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

xxvi The Effects of UV Light and Weather on Plastics and Elastomers

10-3 Material Properties (Dielectric Strength, Tensile Strength, Elongation at Break, andMIT Flex Life) of FEP Film after South Florida Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

10-4 Material Properties (Tensile Strength and Elongation at Break) of FEP Film after SouthFlorida Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

10-5 Electrical Properties of FEP Film after South Florida Exposure . . . . . . . . . . . . . . . . . . . . . . 7712-1 Mechanical Properties and Yellowness Index after Arizona Outdoor Weathering

Exposure for Solvey Solexis Solef® 11010 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8212-2 Yellowness Index after QUV Accelerated Weathering Exposure (UV-B 313) for Solvey

Solexis Solef® 21508 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8212-3 Retention of Mechanical Properties after Outdoor Weathering of Arkema Kynar®

PVDF Film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8312-4 Retention of Mechanical Properties after Xenon Arc Weatherometer

Exposure of PVDF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8314-1 Accelerated Weathering of Solvay Solexis Halar® ECTFE in a Xenon Arc

Weatherometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9115-1 Accelerated Weathering of DuPont Tefzel® 200 ETFE in a Weatherometer . . . . . . . . . . . . 9517-1 Physical Properties and Visual Appearance after Florida and Arizona Outdoor

Weathering for UV-Stabilized DuPont Surlyn® Ionomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10417-2 Physical Properties and Visual Appearance after Accelerated Weathering in an Atlas

Weatherometer for Zinc Ion Type UV-Stabilized DuPont Surlyn® Ionomer . . . . . . . . . . . . . 10517-3 Physical Properties and Visual Appearance after Accelerated Weathering in an Atlas

Weatherometer for Zinc Ion Type UV- and Antioxidant-Stabilized, Pigmented DuPontSurlyn® Ionomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

17-4 Physical Properties and Visual Appearance after Accelerated Weathering in anAtlas Weatherometer for Sodium Ion Type UV- and Antioxidant-Stabilized, PigmentedDuPont Surlyn® Ionomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

17-5 Physical Properties and Visual Appearance after Accelerated Weathering in a QUVWeatherometer for Zinc Ion Type DuPont Surlyn® Ionomer . . . . . . . . . . . . . . . . . . . . . . . . . . 108

18-1 Change in Yellowness Index and Percentage Gloss Retained after OutdoorWeathering Exposure in Arizona, Florida, and New York for GE Plastics Noryl®

Modified PPO. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11020-1 Mechanical Properties Retained after Outdoor Weathering Exposure in Florida for

BASF Capron® Nylon 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11820-2 Mechanical Properties Retained after Outdoor Weathering Exposure in California and

Pennsylvania for LNP Engineering Plastics® Nylon 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11922-1 Material Properties Retained after Outdoor Weathering in California and Pennsylvania

for LNP (a Division of GE Plastics) Glass-Reinforced Nylon 610 . . . . . . . . . . . . . . . . . . . . . 13327-1 Izod Impact and Surface and Appearance Properties after Arizona Outdoor Exposure

of Dow Calibre® 300 6 MFR without and with UV Stabilizer . . . . . . . . . . . . . . . . . . . . . . . . . 14827-2 Mechanical Properties Retained after California and Pennsylvania Outdoor Exposure

of LNP Engineering Plastics PC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14927-3 Mechanical Properties and Surface and Appearance Properties after Arizona

Accelerated Outdoor Weathering and Kentucky Outdoor Weathering for GE Lexan®

S-100 and Lexan® 100 Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15027-4 Mechanical Properties Retained after XW Accelerated Weathering for

GE Lexan® 303 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15127-5 Change in color, �E, after Accelerated Indoor Exposure of GE Lexan® 920A by

HPUV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15130-1 Tensile Strength and Elongation Retained after Arizona Outdoor Weathering of

DuPont Rynite® 545 NC10, Rynite® 545 BK504, and Rynite® 935 BK505 . . . . . . . . . . . . 168

List of Graphs and Tables xxvii

30-2 Tensile Strength and Elongation Retained after Arizona Outdoor Weathering ofDuPont Rynite® 530 NC10 and Rynite® 530 BK503 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

30-3 Tensile Strength and Elongation Retained after Florida Outdoor Weathering ofDuPont Rynite® 530 NC10 and Rynite® 530 BK503 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

30-4 Tensile Strength and Elongation Retained after Florida Outdoor Weathering ofDuPont Rynite® 545 NC10 and Rynite® 545 BK504 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

30-5 Tensile Strength and Elongation Retained after Arizona EMMA and EMMAQUAWeathering of DuPont Rynite® 530 NC10, Rynite® 530 BK503, Rynite® 545 NC10,and Rynite® 545 BK504 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

31-1 Mechanical Properties Retained after Xenon Arc Accelerated Weathering for TiconaVectra® A950, Vectra® A130, Vectra® B950, and Vectra® A540 . . . . . . . . . . . . . . . . . . . . . . 174

36-1 Tensile Strength Retained after United Kingdom Outdoor Weathering Exposure ofNatural, Black, and White Pigmented Victrex® PEEK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

36-2 Tensile Strength Retained after United Kingdom Outdoor Weathering Exposure ofPigmented Victrex® PEEK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186

37-1 Service Life after OutdoorWeathering for Cyanox 2777, Cyasorb UV 531, and CyasorbUV-3346 UV-Stabilized Polyethylene Greenhouse Film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

37-2 Service Life after Outdoor Weathering for Cyasorb UV-3346 UV-StabilizedPolyethylene Greenhouse Film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190

37-3 Mechanical Properties Retained after California and Pennsylvania Outdoor Exposureof Glass-Reinforced LNP Polyethylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190

39-1 Tensile Strength after EMMA Accelerated Weathering of Chevron Phillips Marlex®

HDPE with Channel Black and Furnace Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19839-2 Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex® HDPE with

Various Degrees of Pigment Dispersion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19939-3 Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex® HDPE with

UV Absorber and Various Orange Pigment Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20039-4 Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex® HDPE with

2% Cadmium Yellow Pigment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20139-5 Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex® HDPE with

UV Absorber and Various Yellow Pigments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20239-6 Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex® HDPE with

2% TiO2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20339-7 Surface and Appearance after Accelerated Weathering of Chevron Phillips Marlex®

HDPE with UV Absorber, Various Antioxidants and Green Pigment . . . . . . . . . . . . . . . . . . 20441-1 Elongation Retained after Xenon Arc Weatherometer Exposure of Ethylene-Vinyl

Acetate Polyethylene Copolymer Greenhouse Film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21442-1 Conversions of EMMAQUA to Real-Time Performance by Geographic Location . . . . . . . 21642-2 Tensile Strength after Florida and Puerto Rico Outdoor Weathering of Polypropylene

Containing Various Antioxidant Stabilizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21742-3 Mechanical Properties Retained after California and Pennsylvania Outdoor

Weathering of Glass-Reinforced Polypropylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21842-4 Tensile Strength Retained after Puerto Rico Outdoor Weathering for Polypropylene

Containing Antioxidants and UV Stabilizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21942-5 Color and Gloss Changes after QUV Accelerated Weathering for Polypropylene

Containing Microcal Calcium Carbonate and Pure Calcium Carbonate . . . . . . . . . . . . . . . 22044-1 Material Properties Retained and Surface Erosion after Atlas Weatherometer

Accelerated Weathering of Chevron Phillips Ryton® R4 Polyphenylene Sulfide . . . . . . . . 22545-1 Photo-Oxidation of Polystyrene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227

xxviii The Effects of UV Light and Weather on Plastics and Elastomers

45-2 Mechanical Properties Retained after California and Pennsylvania OutdoorWeathering of Glass-Reinforced General Purpose Polystyrene . . . . . . . . . . . . . . . . . . . . . . 228

46-1 Color Change, �E, after 18 Months of Florida Outdoor Exposure for NOVA ChemicalsStyrosun® HIPS and Other Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232

46-2 Color Change, �E, after 18 Months of Florida Outdoor Exposure and 3000 hours ofAccelerated Weathering for NOVA Chemicals Styrosun® HIPS and Other Materials . . . . 232

46-3 Impact Retention after 3000 hours of Accelerated Weathering for NOVA ChemicalsStyrosun® HIPS and Other Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233

47-1 Mechanical Properties Retained after Outdoor Weathering of Glass-ReinforcedPolysulfone in California and Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239

49-1 Surface and Appearance Properties after Arizona Outdoor Weathering of Dow Tyril®

SAN Copolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24451-1 Exposure Results of Various Plasticized Films with Varying Thicknesses . . . . . . . . . . . . . 25051-2 Outdoor Life of DOP-Plasticized 4 mil (100 µm) Thick Films With Varied Plasticizer

Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25051-3 Direct Weathering of Select Plasticizers in PVC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25151-4 Underglass Weathering of Select Plasticizers in PVC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25151-5 Titanium Dioxide in Films of Three Thicknesses Exposed in Florida . . . . . . . . . . . . . . . . . . 25253-1 Color Change after Accelerated QUV Weathering of Novatec Novaloy® 9000

ABS/PVC Alloy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25855-1 Color Change, �E, after HPUV and Xenon Arc Accelerated Indoor Exposure of Dow

Chemical Pulse 1745 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26156-1 Degradation of Various Mulching Films after Exposure to Natural Solar Radiation at

Different Periods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26456-2 Days From Mulching to Appearance of Fracture in Film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26556-3 Degradation of Mulching Films Incorporated with Different Starch Content . . . . . . . . . . . . 26559-1 Surface and Appearance Changes after Xenon Arc Accelerated Weathering Exposure

(GM Specifications) of Recticel Colo-Fast® Polyurethane RIM System . . . . . . . . . . . . . . . 27459-2 Surface and Appearance Changes after Xenon Arc Accelerated Weathering Exposure

(Japanese Specifications) of Recticel Colo-Fast® Polyurethane RIM System . . . . . . . . . . 27559-3 Surface and Appearance Changes after Fadeometer Accelerated Weathering

Exposure of Recticel Colo-Fast® Polyurethane RIM System . . . . . . . . . . . . . . . . . . . . . . . . 27662-1 Retention of Mechanical Properties after Xenon Arc Exposure for Black UV Grades

of Advanced Elastomer Systems Santoprene™ TPV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28562-2 Material Properties after Arizona Outdoor Exposure for Black UV Grades of Advanced

Elastomer Systems Santoprene™ TPV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28662-3 Material Properties after Arizona Outdoor Exposure with Spray for Black UV Grades

of Advanced Elastomer Systems Santoprene™ TPV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28762-4 Material Properties after Florida Outdoor Exposure for Black UV Grades of Advanced

Elastomer Systems Santoprene™ TPV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28862-5 Material Properties after Florida Outdoor Exposure with Spray for Black UV Grades

of Advanced Elastomer Systems Santoprene™ TPV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28962-6 Material Properties after EMMA Accelerated Exposure with Spray for Black UV Grades

of Advanced Elastomer Systems Santoprene™ TPV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29062-7 Material Properties after EMMAQUA Accelerated Exposure for Black UV Grades of

Advanced Elastomer Systems Santoprene™ TPV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29162-8 Material Properties after Xenon Arc Exposure for Black UV Grades of Advanced

Elastomer Systems Santoprene™ TPV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29262-9 Material Properties after Xenon Arc SAE J1960 Exterior Automotive Testing for

Advanced Elastomer Systems Santoprene™ TPV High-Flow Grades . . . . . . . . . . . . . . . . . 293

List of Graphs and Tables xxix

62-10 Material Properties after UV-CON Accelerated Indoor Exposure of PolyOne Forprene®

Olefinic Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29462-11 UV Resistance after Accelerated UV Light Exposure of PolyOne Forprene® Olefinic

Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29562-12 Ozone Resistance of PolyOne Forprene® Olefinic Thermoplastic Elastomer . . . . . . . . . . 29562-13 Ozone Resistance of Advanced Elastomer Systems Santoprene™ Olefinic

Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29662-14 Ozone Resistance of Dow Chemical Company’s Engage™ Olefinic Thermoplastic

Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29762-15 Ozone Resistance of Advanced Elastomer Systems Santoprene™ Black Olefinic

Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29863-1 Material Properties Retained and Surface and Appearance after Florida Outdoor

Weathering for DuPont Hytrel® Polyester Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . 30263-2 Material Properties Retained and Surface and Appearance after Florida

Outdoor Weathering for DuPont Hytrel® 40D Polyester Thermoplastic Elastomer withCarbon Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303

63-3 Material Properties Retained after Florida Outdoor Weathering for DuPont Hytrel®

5556 Polyester Thermoplastic Elastomer with Carbon Black . . . . . . . . . . . . . . . . . . . . . . . . 30463-4 Material Properties Retained and Surface and Appearance after Florida Outdoor

Weathering for Varying Thicknesses of DuPont Hytrel® 6345 Polyester ThermoplasticElastomer Films with Carbon Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305

63-5 Material Properties Retained after Carbon Arc Accelerated Weathering for DuPontHytrel® 40D Polyester Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306

63-6 Material Properties Retained after Carbon Arc Accelerated Weathering for DuPontHytrel® 5556 Polyester Thermoplastic Elastomer with Varying Levels ofCarbon Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307

63-7 Material Properties Retained and Surface and Appearance after Carbon ArcAccelerated Weathering for DuPont Hytrel® HT-X-3803 and 4056 PolyesterThermoplastic Elastomer with Varying Levels of Carbon Black . . . . . . . . . . . . . . . . . . . . . . 308

63-8 Soil Burial and Fungus Resistance for DuPont Hytrel® Polyester ThermoplasticElastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309

65-1 Ozone Resistance of Kraton® Styrenic Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . 31466-1 Properties Retained after Fadeometer Accelerated Weathering for Noveon Estane®

58202 and Estane® 58300 Urethane Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . 31766-2 Properties Retained after Fadeometer and QUV Accelerated Weathering for Noveon

Estane® 58315 Urethane Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31866-3 Properties Retained after Fadeometer Accelerated Weathering for Noveon Estane®

58315 and Estane® 58863 Urethane Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . 31967-1 Material Properties after Florida Outdoor Weathering of Eliokem Chemigum® Nitrile

Thermoplastic Elastomer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32468-1 Comparison of Ozone Resistance and Weather Resistance for a Few Thermoset

Elastomers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32670-1 Color Pigments Recommended for Use in Hypalon® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33070-2 Material Properties Retained and Color Change after Outdoor

Weathering and Accelerated Weathering of DuPont Elastomers Hypalon®

Chlorosulfonated Polyethylene Rubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33270-3 Material Properties Retained and Color Change after Arizona Outdoor Weathering for

DuPont Elastomers Hypalon® 40 Chlorosulfonated Polyethylene Rubber . . . . . . . . . . . . . 333

xxx The Effects of UV Light and Weather on Plastics and Elastomers

70-4 Material Properties Retained and Color Change after Florida and Delaware OutdoorWeathering for Wire Cable Compound DuPont Elastomers Hypalon® 40Chlorosulfonated Polyethylene Rubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334

70-5 Surface and Appearance and Mildew Resistance after Texas and CaliforniaOutdoor Weathering for Green Hose Cover Compound DuPont Elastomers Hypalon®

40 Chlorosulfonated Polyethylene Rubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33570-6 Material Properties Retained and Surface and Appearance after Florida Outdoor

Weathering for White DuPont Elastomers Hypalon® 40 Chlorosulfonated PolyethyleneRubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336

70-7 Material Properties Retained and Surface and Appearance after DelawareOutdoor Weathering for DuPont Elastomers Hypalon® 20 ChlorosulfonatedPolyethylene Rubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337

70-8 Material Properties Retained and Surface and Appearance after Panama OutdoorWeathering for Pond Liner Formulation DuPont Elastomers Hypalon® 45Chlorosulfonated Polyethylene Rubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338

70-9 Material Properties Retained and Color Change after EMMA and EMMAQUAAccelerated Outdoor Weathering for Black DuPont Elastomers Hypalon® 40Chlorosulfonated Polyethylene Rubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339

70-10 Material Properties Retained and Color Change after Xenon Arc WeatherometerExposure for Black DuPont Elastomers Hypalon® 40 Chlorosulfonated PolyethyleneRubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340

72-1 Mechanical Properties Retained after Outdoor and Accelerated Outdoor Weatheringof White, Randomly Selected, Unstrained EPDM Terpolymer . . . . . . . . . . . . . . . . . . . . . . . . 349

72-2 Mechanical Properties Retained after Outdoor and Accelerated Outdoor Weatheringof Black, Weather Resistant, Unstrained EPDM Terpolymer . . . . . . . . . . . . . . . . . . . . . . . . . 350

72-3 Mechanical Properties Retained after Outdoor and Accelerated Outdoor Weatheringof Black, Randomly Selected, Unstrained EPDM Terpolymer . . . . . . . . . . . . . . . . . . . . . . . . 351

72-4 Mechanical Properties Retained and Color Change after Outdoor Weathering,Accelerated Outdoor Weathering by EMMAQUA, and Accelerated Weathering with aXenon Arc Weatherometer for Black Exxon Vistalon EPDM Terpolymer . . . . . . . . . . . . . . 352

72-5 Material Properties Retained and Color Change after Arizona Outdoor WeatheringWith and Without Water Spray Added for Black Exxon Vistalon 5600 EPDMTerpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353

72-6 Mechanical Properties Retained and Color Change after Arizona Outdoor Weatheringof Black Exxon Vistalon 5600 EPDM Terpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354

72-7 Material Properties Retained after Florida Outdoor Weathering and AcceleratedOutdoor Weathering by EMMA for Black, Weather Resistant, Strained EPDMTerpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355

72-8 Material Properties Retained and Color Change after Florida Outdoor WeatheringWith and Without Water Spray Added for Black Exxon Vistalon 5600 EPDMTerpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356

72-9 Material Properties Retained and Surface and Appearance after Florida OutdoorWeathering of Weatherable EPDM Terpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357

72-10 Mechanical Properties Retained after Florida Outdoor Weathering and AcceleratedOutdoor Weathering by EMMA for Black, Randomly Selected, Strained EPDMTerpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358

72-11 Mechanical Properties Retained after Florida Outdoor Weathering and AcceleratedOutdoor Weathering by EMMA for White, Randomly Selected, Strained EPDMTerpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359

List of Graphs and Tables xxxi

72-12 Material Properties Retained and Color Change after Florida Outdoor Weathering ofBlack EPDM Terpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360

72-13 Material Properties Retained and Color Change after Accelerated OutdoorWeathering by EMMA and EMMAQUA and Accelerated Weathering in a Xenon ArcWeatherometer for Black Exxon Vistalon 5600 EPDM Terpolymer . . . . . . . . . . . . . . . . . . . 361

72-14 Mechanical Properties Retained and Color Change after Arizona Accelerated OutdoorWeathering by EMMA and EMMAQUA for Black Exxon Vistalon 5600 EPDMTerpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362

72-15 Mechanical Properties Retained after Accelerated Weathering in a UV-CON and aXenon Arc Weatherometer for White, Randomly Selected, Strained EPDMTerpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363

72-16 Mechanical Properties Retained after Accelerated Weathering in a UV-CON and aXenon Arc Weatherometer for White, Randomly Selected, Unstrained EPDMTerpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364

72-17 Mechanical Properties Retained after Accelerated Weathering in a UV-CON and aXenon Arc Weatherometer for Black, Weather Resistant, Strained EPDMTerpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365

72-18 Mechanical Properties Retained after Accelerated Weathering in a UV-CON and aXenon Arc Weatherometer for Black, Randomly Selected, Unstrained EPDMTerpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366

72-19 Mechanical Properties Retained and Color Change after Accelerated Weathering ina Xenon Arc Weatherometer of Black Exxon Vistalon 5600 EPDM Terpolymer . . . . . . . . 367

72-20 Mechanical Properties Retained after Accelerated Weathering in a UV-CON and aXenon Arc Weatherometer for Black, Weather Resistant, Unstrained EPDMTerpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368

72-21 Mechanical Properties Retained after Accelerated Weathering in a UV-CON and aXenon Arc Weatherometer of Black, Randomly Selected, Strained EPDMTerpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369

72-22 Surface and Appearance and Ozone Resistance of Exxon Vistalon EPDMTerpolymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370

72-23 Surface and Appearance and Ozone Resistance of EPDM Terpolymer . . . . . . . . . . . . . . . 37173-1 Mechanical Properties Retained and Color Change after Arizona Outdoor Weathering

and Accelerated Outdoor weathering by EMMAQUA and Xenon Arc AcceleratedOutdoor Weathering for Black DuPont Neoprene® W Neoprene Rubber . . . . . . . . . . . . . . 374

73-2 Material Properties Retained, Hardness Change, and Color Change after Arizona andFlorida Outdoor Weathering for Black DuPont Neoprene® W Neoprene Rubber . . . . . . . 375

73-3 Mechanical Properties Retained and Color Change after Arizona Outdoor Weatheringand Arizona OutdoorWeathering with Spray for Black DuPont Neoprene® W NeopreneRubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 376

73-4 Material Properties Retained, Hardness Change, and Color Change after ArizonaOutdoor Weathering and Arizona Outdoor Weathering with Spray for Black DuPontNeoprene® W Neoprene Rubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377

73-5 Material Properties Retained, Hardness Change, and Color Change after FloridaOutdoor Weathering and Florida Outdoor Weathering with Spray for Black DuPontNeoprene® W Neoprene Rubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378

73-6 Material Properties Retained, Hardness Change, and Color Change after Xenon ArcAcceleratedWeathering and EMMA and EMMAQUA Accelerated Outdoor Weatheringfor Black DuPont Neoprene® W Neoprene Rubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379

xxxii The Effects of UV Light and Weather on Plastics and Elastomers

73-7 Mechanical Properties Retained and Color Change after EMMA and EMMAQUAArizona Accelerated Outdoor Weathering for Black DuPont Neoprene® W NeopreneRubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380

73-8 Mechanical Properties Retained and Color Change after Xenon Arc AcceleratedWeathering for Black DuPont Neoprene® W Neoprene Rubber . . . . . . . . . . . . . . . . . . . . . . 381

73-9 Ozone Resistance after Exposure of Black DuPont Neoprene® W Neoprene Rubber . . 38274-1 Ozone Resistance of Japanese Synthetic Rubber JSR BR Polybutadiene Rubber . . . . . 38475-1 Ozone Resistance of Goodyear Natsyn® 2200 Polyisoprene Rubber as per the

Annulus Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38675-2 Ozone Resistance of Goodyear Natsyn® 2200 Polyisoprene Rubber as per ASTM

D1171 Loop Ozone Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38775-3 Ozone Resistance of Goodyear Natsyn® 2200 Polyisoprene Rubber as per the Static

Strip Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38875-4 Ozone Resistance of Goodyear Natsyn® 2200 Polyisoprene Rubber as per the Kinetic

Stretch Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38976-1 Gloss Retained after Xenon Arc Accelerated Weatherometer Exposure of

Polyurethane Rubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39277-1 Change in Mechanical Properties after Florida and Michigan Outdoor Weathering for

Dow Corning Silastic® Silicone Rubber as per ASTM D518, Method A . . . . . . . . . . . . . . . 39377-2 Change in Mechanical Properties after Florida and Michigan Outdoor Weathering for

Dow Corning Silastic® Silicone Rubber as per ASTM D518, Method B . . . . . . . . . . . . . . . 394A2-1 Comparative Properties and Performance Chart—Coil Coating Topcoats . . . . . . . . . . . . . 399

Introduction

How to Use This Book

This data bank publication presents the resultsof weathering exposure for more than seventy-sevenfamilies of plastics and elastomers. Each chapterrepresents a single generic family. Data appears intextual, tabular, and graphical forms. Textual infor-mation is useful as it is often the only informationavailable or the only way to provide an expansivediscussion of test results. This is especially true inthe case of weathering data where many results arequalitative.

Tables and graphs provide detailed test results ina clear, concise manner. Careful study of a table orgraph will show how variations in material, exposureconditions, and test conditions influence a material’sphysical characteristics.

Each table or graph is designed to stand alone,be easy to interpret, and provide all relevant andavailable details of test conditions and results. Theinformation’s source is referenced to provide anopportunity for the user to find additional informa-tion. The source information might also help to indi-cate any bias which might be associated with the data.

Weatherability

Weather Defined

Webster’s dictionary defines weathering as a“Noun. Action of the elements in altering the color,texture, composition, or form of exposed objects.Weather: to expose to air; to season, dry, pul-verize, discolor, etc., by exposure to air.” Inessence, weathering is the natural tendency of mate-rials to return—corrode, oxidize, chalk, permeate,delaminate, depolymerize, flex crack, etc.—to theirelemental forms.

Variations in Natural Weathering

Weathering is variable by region, season, year,etc. Exposure to a subtropical climate such as Florida

can easily be twice as severe as exposure in northerlyregions. This is due to the increase in UV radiationcaused by the higher average sun angle and excep-tionally moist climate. On the other hand, Arizonamay offer an increased UV radiation degradation,but has a much lower rate of deterioration due tohumidity.

Seasonal variations such as higher tempera-ture and increased UV radiation (due to higher sunangle in the summer) can cause summer exposureto be two to seven times as severe as winter expo-sure in the same place. Variations in weather canchange from year to year making one year twiceas severe as the last. Natural (outdoor), acceleratedoutdoor, and accelerated machine testing attempt torecreate weathering and its variability, usually underconditions more severe than normally encountered.

Testing for Weatherability

The primary purpose served by examining dataon weathering of materials is to predict any potentialchanges of both physical properties and appear-ance of a part made from those materials. Data onthe aging behavior of plastics are acquired throughaccelerated tests and/or actual weather exposure.These tests serve as a means for comparison of mate-rials and can also be exploited to determine the abilityof the material to serve its function when formed intoparts and used in a particular environment. Com-parisons between materials are made by measuringthe retention of properties (e.g., impact strength,gloss, tensile strength, yellowness index) significantto the application as a function of exposure time.The demand for new products has shortened thetime available for determining the durability of aparticular material. Therefore, accelerated weather-ing is increasingly used in an attempt to predict thelong-term environmental effects in less time than thereal-time working life expectancy.

Natural sunlight is not standard; there are vari-ations in clouds, smog, angle of the sun, rain,industrial environments, etc. Likewise options and

2 The Effects of UV Light and Weather on Plastics and Elastomers

approaches to the testing of plastic materials andtheir additives vary among individuals and changeas theory becomes application. As a result, thereare differing opinions as to the validity of testing,both with natural exposure and under acceleratedor laboratory conditions. Testing and reliance ontest results is necessary in the product developmentprocess to determine the durability of materials inparticular applications. An accelerated weatheringmethod correlates with real-time exposure testingwhen specific defects can be generated in a mate-rial with an acceptable precision in a repeatable,shorter interval. Many manufacturers and suppliersworldwide find the correlations acceptable and haveadopted test specifications for accelerated and artifi-cial weathering.

The factors that influence the degree of weather-ing are:

• Solar radiation (usually UV)• Moisture (dew, humidity, rain)• Heat (surface temperature of the

material)• Pollutants (ozone, acid rain)• Salt water

Because these factors vary so widely over the earth’ssurface, the weathering of materials is not an exactscience. It is virtually impossible to rank the degen-erative power of temperature, moisture, and UVradiation. Most materials are weathered by a combi-nation of these factors, but some are degenerated bymoisture alone or UVradiation alone. Before one candetermine the appropriate test procedure for a partic-ular material, it is important to become familiar withthe elements of natural weathering, how they work,and how they may work together to cause adverseeffects on the durability of a given part.

Elements of Weather

The process of weathering includes the actionof elements in addition to the effects of radiation.The combination of these factors produces an effectgreater than the sum of the individual effects; degra-dation due to radiation is accelerated when the otherelements operate at the same time. This synergism,

or reinforcing action, has been demonstrated manytimes in studies on durability.

Radiation

UV wavelengths from sunlight are an impor-tant component in outdoor degradation. The energyfrom sunlight is mainly visible light (700–400 nm),infrared (manifested as heat), and UV light (400–10 nm).∗ Although UV radiation amounts to only 3%of the total radiation that reaches the earth, it is ener-getic enough to cause chemical reactions, weatheringof polymers, and fading of certain dyes. The energycontained in UV light is capable of directly rupturingpolymer chains (chain scission), and, in the pres-ence of oxygen, UV radiation causes oxidation ofplastics. The wavelengths that cause the most dam-age to polymers are in the UV range, 290–400 nm.At the shortest wavelengths in the UV region, thephoton energy is of the same order of magnitudeas the energies of the bonds in common polymers.The intensity of this short-wavelength radiation isstrongly dependent on season and location.[1]

The infrared (felt as heat) portion of sunlightwarms plastics and accelerates the harmful effectsof UV light. In the continental United States, weath-ering conditions are several times more severe insummer than in winter. This is partly due to theincrease in the amount of UV light that penetratesthe atmosphere and reaches the ground in the summerand partly due to higher temperatures.[2]

The solar UV radiation spectrum is divided intothree ranges. UV-A is the energy with wavelengthsbetween 400 and 315 nm. UV-B is the spectrum from315 to 290 nm. UV-C includes solar radiation below290 nm. The wavelength regions of UV radiationand their characteristics relative to degradation ofmaterials are listed below.

Wavelength Regions of UV Radiation

UV-A400–315 nm

Always present in sunlight; 400 nmupper limit for UV-A is the bound-ary between visible light and UVlight; energy at 315 nm boundary

∗Nanometers (nm) are commonly used for measuring wave-lengths. 1 nm = 10−9 m.

Introduction 3

begins to cause adverse effectsand pigmentation changes in humanskin and some polymers.

UV-B315–290 nm

Includes the shortest wavelengthsfound at the earth’s surface; respon-sible for severe polymer damage;absorbed by window glass; UV lightabsorption by ozone varies withsolar altitude; 290–315 nm is com-pletely absorbed at altitudes below14◦, at 19◦ solar cutoff is 310 nm,at 40◦ solar cutoff is 303 nm, atsolar altitudes between 60◦ and90◦ maximum UV-B reaches theearth’s surface with a solar cutoff atapproximately 295 nm.

UV-C290–100 nm

The UV-C range is a sharp cutoffof solar radiation at the earth’s sur-face due to complete absorption byozone; found only in outer space.

UV-B wavelengths cause the most damage to poly-meric materials.

Moisture

A high incidence of moisture has importantimplications on the durability of a part. It is oftenthe case that water is not destructive in itself, butwater causes damage by bringing oxygen into inti-mate contact with the material and thereby promotesoxidation.

Generally, the potential for degeneration fromdew exceeds that associated with rain. In Florida,materials are exposed to outdoor wetness an aver-age of eight hours per day, or about 2900 hours ofmoisture per year. Materials are wet from dew or con-densation more frequently and for longer durationsthan from rain.

To condense dew, a material must be coolerthan the dew point temperature of air. This usuallyoccurs during night when solid objects lose their heatthrough radiation.The fact that materials are exposedprimarily to dew and not rain affects the type ofdegradation that will occur. Dew is saturated withoxygen and lies on materials for hours. The resultinginternal oxidation and leaching of soluble additives

leaves the material vulnerable. The severity of mois-ture attack increases dramatically with increasingtemperature.

Radiation and Water

Radiation and water, two components ofweather, tend to operate at different times. However,materials can be irradiated after having been wet byrain or when they have high moisture content fromovernight high humidity. In this situation, radiationcan accelerate the effect of water, and vice versa.[3]

It is also possible for radiation to raise the tem-perature of a material to the point where solutionor hydrolysis can occur. In the case of plasticizers,vinyl coatings and plastics may delaminate if theyare appreciably soluble in water at elevated temper-atures. Strength of polyester laminates can also bereduced through attack by water either on the resinitself or on the bond between the resin and the glassfiber. These actions are not so marked as in actualimmersion in hot water, but they can contribute tothe degradation process.[3]

Radiation and Oxygen

A natural weathering combination that has prob-ably even greater effect is oxygen and radiation,referred to technically as photo-oxidation. Materialssubjected to oxygen are degraded much faster in thepresence of radiation than in its absence. For exam-ple, discoloration of polystyrene occurs more rapidlywhen irradiation takes place in air or oxygen. Withsaturated polymers there is little damage from oxy-gen at room temperature if UV radiation is absent.[3]

Reducing the Effect of Radiation

Because the effects of heat, oxygen, and radi-ation can be severe, attempts are made to reducesusceptibility to one or more of the factors. It is dif-ficult to remove the potential exposure to heat andoxygen in an environment, and radiation is often themost important of the three factors. Thus, there areseveral options other than additives that could reduceexposure of a polymer to radiation.[3]

4 The Effects of UV Light and Weather on Plastics and Elastomers

• A transparent polymer does not absorbradiation, therefore, minimizing theeffects of the radiation. In the realworld it is difficult to achieve completetransparency as evidenced by poly-ethylene, which is transparent to UVradiation but readily degrades uponexterior exposure.[3]

• Manufacture polymers whose bondstrengths exceed the energy availablein solar radiation. The potential forsuccess of this method is limited by thefact that most such combinations formsimple compounds instead of polymer-izing. These materials are often readilydecomposed by water or oxygen. Sili-cones are an example of this polymertype with a silicon-oxygen backboneand organic side groups. “The silicon-oxygen bond is only broken by radia-tion of wavelengths below 270 nm, andthis is not received at the earth’s sur-face. The organic groups are necessaryfor the material to have the propertiesrequired of a polymer; without themthe material is quartz or silica—SiO2.Fluorocarbon polymers are anotherexample. Although fluorine is not partof the molecular backbone, the highstrength of the fluorine-carbon bonds inthe side groups contributes markedly totheir excellent exterior durability.”[3]

• “The final and most common pro-cedure in minimizing the effect ofradiation is to prevent the polymer fromabsorbing it. If the material does nothave to be transparent this can readilybe accomplished through the incorpo-ration of pigments that reflect radiationor absorb it preferentially. Reflectionusually occurs at the pigment surfaceswithin the resin so that the radiation hasto pass through the top layers twice.Some degradation can, therefore, occurat the surface, and this is why materi-als frequently lose gloss on exposure.For complete absorption to take placethe pigment must be black. Incorpora-tion of black pigment is very effective,as shown by the increase in durability

of polyethylene from one year to 20years with the addition of 1 per centcarbon black. The color, however, isnot always acceptable. For other col-ors titanium, zinc or iron oxides canbe used, but higher concentrations arerequired.”[3]

Surface Temperature andThermal Degradation

Surface temperature is the most variable factor inweather. An automobile driven at 55 mph on a high-way will attain a surface temperature near ambient.The same car, locked and parked in direct sunlight,can reach a surface temperature 30◦C above ambient.At night, with no wind and a clear sky, the surfacetemperature can drop 8◦C below ambient.

Color is also a contributing factor in surfacetemperature. White materials typically attain a tem-perature 10◦C–15◦C lower than black materials. Itis difficult to match outdoor temperature differencesbetween dark and light materials in the laboratory.For example, the introduction of air for heating andcooling will reduce temperature differences betweencolors. While temperature is an important factor inweathering, it is also important to note that not allmaterials show increased degradation with increasedtemperature.

Thermal degradation of polymers, moleculardeterioration as a result of overheating, can resultfrom exposure to the elements. At high temperaturesthe components of the long-chain backbone of thepolymer begin to separate (molecular scission) andreact with one another to change the properties ofthe polymer.Thermal degradation generally involveschanges to the molecular weight (and molecularweight distribution) of the polymer. Significant ther-mal degradation can occur at temperatures muchlower than those at which mechanical failure is likelyto occur.[4]

Material Properties Post-Exposure

The many concurrent chemical processes takingplace in polymers exposed to UV radiation resultin several different modes of damage, each pro-gressing at a different rate. It is usually the criticalfirst-observed damage process that determines the

Introduction 5

useful service life of the product. For example, apolyvinyl chloride (PVC) window frame exposed tosunlight undergoes discoloration, chalking, loss ofimpact strength, and a reduction in tensile proper-ties as well as a host of other chemical changes. It is,however, the discoloration (or the uneven yellowing)of the window frame that generally determines itsservice life. However, with continued use, other dam-age such as chalking and eventually loss of impactresistance (leading to cracking) can occur makingthe product even more unacceptable. The two criti-cal modes of photodamage applicable to most naturaland synthetic materials are yellowing discolorationand loss of mechanical integrity.[5]

Exposure of many plastics to UV radiationcauses a loss in their mechanical properties and/or achange in their appearance.Typical property changesinclude:

• Reduced ductility and embrittlement• Chalking• Color changes• Yellowing• Cracking

Photodegradation causes a loss of strength,impact resistance, and mechanical integrity of plas-tics exposed to UV radiation. These changes inmechanical properties reflect the result of polymerchain scission (and/or cross-linking). The molecu-lar changes of these materials can be characterizedthrough the study of solution viscosity and thegel permeation characteristics. The embrittlementproduced by UV radiation exposure is often evalu-ated by measuring the impact resistance (toughness)of the material.[5]

Deterioration in appearance produced by UVradiation exposure can be evaluated by measuringcolor shift and gloss. The observed color shift, �E,may be affected by the change in gloss. While thedetermination of gloss is straightforward, techniquesfor evaluating color shift may vary considerably.

A very sensitive method of quantifying thechange in the mechanical properties of polymersbrought about by the effects of weathering is todetermine the penetration energy on weatheredspecimens. If the unirradiated reverse side of thespecimens is impacted, the irradiated front sideexperiences a sudden tensile stress, so that even the

slightest deterioration gives a clear reduction in themeasured values. This test is therefore an excellentindicator of weathering resistance. In contrast, if theimpact is on the irradiated side, as most frequentlyhappens in practice, a reduction in toughness is onlyobserved after much longer exposure times. Mea-surable reductions in the values of properties suchas breaking stress and modulus of elasticity are alsoseen only at a much later stage.[6]

UV Additives and Stabilizers

UV sensitivity is based on complex photolyticand photo-oxidative mechanisms that lead to mate-rial degradation as a result of chain scission. Reactiveradicals are produced by the energy-rich UV light.In the presence of oxygen the plastics are oxidized(photo-oxidation).

Two methods of UV stabilization are com-monly used: UV absorbers (e.g., benzotriazoles) andUV stabilizers (e.g., hindered amines). Hydroxy-benzotriazoles preferentially absorb light in the 300–400 nm wavelength range. They dissipate the lightenergy by a tautomeric process, which protects thepolymer by preventing it from absorbing harm-ful radiation. Hindered amines, on the other hand,act as radical scavengers. Through the formationof nitroxyl radicals, hindered amines terminate anddeactivate alkyl radicals and peroxy radicals, whichare known to participate in the photo-oxidation pro-cess. While functioning as radical scavengers, thestabilizing species (the nitroxyl radical) is regen-erated and continues to scavenge.[7]

Effective light absorbers such as benzotriazoles,benzophenones, and phenyl esters as well as hin-dered amine light stabilizers (HALS) are presentlyused in plastics formulations intended for outdooruse (usually at a 0.05–2.0 wt% level). Improved sta-bilizers are introduced into the market periodically.[5]

In conventional light stabilization by pigmentssuch as carbon black and titanium dioxide, the UVradiation is absorbed by the pigments and chainscission of the polymer is prevented. The solublelight stabilization systems are combinations of UVabsorbers and radical interceptors. UV absorbersconvert UV light into harmless thermal energy. Rad-ical interceptors or HALS react with spontaneouslyforming radicals to form harmless derivatives.

6 The Effects of UV Light and Weather on Plastics and Elastomers

UV Absorbers

UV absorbers or stabilizers are most efficientwhen used in materials that have a thick crosssection because the amount required is a func-tion of concentration and thickness. Thus, a plastic20 mils (0.5 mm) thick might be stabilized with 0.5%absorber but requires 1% at 10 mils (0.25 mm) and2% at 5 mils (0.125 mm). This relation is not strictlylinear; effectiveness is reduced at higher concentra-tions so that more is required than calculated fromthe relationship.[6]

UV absorbers can be rather specific in theiraction—even absorbers that are closely relatedchemically may show large differences in effective-ness with different resins.As a result, comprehensivetests are needed to determine the type and amountof absorber to be used with any given polymer.It must also be appreciated that absorbers do notlast indefinitely, but are slowly degraded, and thatthe absorption they are intended to prevent willultimately occur.[6]

Hindered Amine Light Stabilizers

With organic light stabilizers such as hin-dered amines, increasing the stabilizer level in the

composition will have little or no impact on pro-cessibility of the resin. The cost, however, will besignificantly affected because the contribution ofthe stabilizer cost to the total cost of a product suchas greenhouse films can be as much as 30%.

Antioxidants

Antioxidants are also commonly used to aidin UV stabilization. Although antioxidants are nei-ther light stabilizers nor UV absorbers, they oftenimprove the overall weatherability of the polymerwhen used in combination with a UV absorber orlight stabilizer. They do this by interrupting thefree-radical process during photo-oxidation.[7]

UV Inhibitors

UV inhibitors, commonly referred to as UVIs,are chemical compounds that absorb UV light anddisperse the energy contained in UV radiation in aform that is less harmful to the plastic. Most materialssynthesized for the purpose of being used as UVIsare transparent and essentially colorless, but thereare also some pigments and dyes that function asUVIs.[2]

Test Environments

Indoor and Interior Exposure

During indoor exposure, products are subjectedto UV radiation from fluorescent lights as well asfrom glass-filtered UV rays transmitted through win-dows. The type of light source, its energy flux, andits distance from the specimens determine the inten-sity of the radiation impinging on the surface ofthe part.

Glass of any type acts as a filter on the sunlightspectrum. The shorter, most damaging wavelengthsare the most greatly affected. Ordinary window glassis essentially transparent to light above 370 nm.However, the filtering effect becomes more pro-nounced with decreasing wavelength. Windshieldglass is thicker than window glass; it acts as a moreefficient filter. Safety features associated with wind-shield glass (e.g., tinting and plastic) add to thefiltering efficiency.Almost all UV light is filtered out

by windshield glass, and the most damaging wave-lengths below 310 nm are completely filtered out.

Outdoor Testing

Real-time weathering data from natural envi-ronment exposure programs remain the standard towhich all other weathering data are compared. Threeof the most commonly used harsh aging sites areArizona, Florida, and Japan. Arizona is importantbecause of its high annual radiation and ambienttemperature. Southern Florida is unique becauseof its high radiation combined with high rainfalland humidity. These two areas have become USand international reference climates for gauging thedurability of materials since they represent the worstcase for applications in the northern hemisphere.

8 The Effects of UV Light and Weather on Plastics and Elastomers

With all outdoor tests it is important to be awareof bias introduced by the choice of location. Detailsabout a few representative test sites are listed in thechart above.

In Miami, Florida, there are approximately 110sun hours per month. This is a total of 1200–1300 sunhours per year. With a 45◦ due south exposure, testspecimens receive approximately 150,000 langleysper year.

Accelerated Outdoor Tests

In outdoor tests, the usual standard procedurecalls for specimen exposure on racks facing duesouth at an angle of 45◦. These are conditions thatoffer a maximum direct sunlight exposure and inten-sity. This tilt is also preferable since it allows forsome drainage and wash off during rains. Sourcesof radiation for outdoor exposure tests include bothdirect and reflected sunlight. In a further attemptto accelerate outdoor effects, many studies are con-ducted in tropical as well as hot, dry climates suchas Florida and Arizona in the United States, andPanama, Germany, and Japan to obtain the most wideranging and severe environments possible. Outdooraccelerated weathering is a relatively recent tech-nique. It relies heavily on technology to follow thetrack of the sun and to keep the sample at a constanttemperature.

Equatorial Mount with Mirrors for Acceleration(EMMA): Natural sunlight and special reflectingmirrors are used to concentrate sunlight to the inten-sity of about eight suns. The test apparatus followsthe sun track with mirrors positioned as tangents to animaginary parabolic trough. The axis is oriented in anorth–south direction, with the north elevation hav-ing the capability for periodic altitude adjustments.A blower directs air over and under the samples tocool the specimens.This limits the increase in surfacetemperatures of most materials to 10◦C (50◦F) abovethe maximum service temperature that is reachedby identically mounted samples exposed to directsunlight at the same times and locations without con-centration. Exposed periods of 6 and 12 months havebeen correlated to about 2.5 and 5 years of actualaging in a Florida environment, respectively.

Equatorial Mount with Mirrors for AccelerationPlus Water (EMMAQUA): Natural sunlight andspecial reflecting mirrors are used to concentratesunlight to the intensity of about eight suns. In addi-tion to intensifying the power of the sun, a waterspray is used to induce moisture weathering con-ditions. The test apparatus follows the sun trackwith mirrors positioned as tangents to an imaginaryparabolic trough. The axis is oriented in a north–south direction, with the north elevation having thecapability for periodic altitude adjustments.Ablowerdirects air over and under the samples to cool thespecimens. This limits the increase in surface tem-peratures of most materials to 10◦C (50◦F) abovethe maximum service temperature that is reachedby identically mounted samples exposed to directsunlight at the same times and locations without con-centration. Exposure to EMMAQUAis considered tobe the harshest exposure.

Conventional Aging

This test method, which may occur in many dif-ferent geographic locations (e.g., Florida, Arizona,and Okinawa, Japan), is real-time exposure at a45◦ tilt from the horizontal. Direct exposures areintended for materials that will be used outdoors andsubjected to all elements of weather. Exposure timesare generally 6, 12, 24, and 48 months. Location isan important factor in the harshness of this test. Theassumption is that test results from a hostile environ-ment will prevail in more moderate conditions.

Conventional Aging with Spray

This test method, which may occur in many dif-ferent geographic locations (e.g., Florida, Arizona,and Okinawa, Japan), is real-time exposure at a45◦ tilt from the horizontal with a water sprayused to induce moisture weathering conditions. Theintroduction of moisture plays an important rolein improving both the relevance and reproduci-bility of the weathering test results. The purpose ofwetting is twofold. First, the introduction of waterin an otherwise arid climate induces and acceler-ates some degradation modes that do not occur asrapidly, if at all, without moisture. Second, a ther-mal shock causes a reduction in specimen surface

Test Environments 9

temperatures, as much as 14◦C (57◦F). This resultsin physical stresses that accelerate the degradationprocess. Spray nozzles are mounted above the faceof the rack at points distributed to ensure uniformwetting of the entire exposed area. Distilled wateris sprayed for four hours preceding sunrise to soakthe samples, and then twenty times during the day in15-second bursts. Direct exposures are intended formaterials that will be used outdoors and subjected toall elements of weather. Exposure times are generally6, 12, 24, and 48 months. Location is an importantfactor in the harshness of this test. With all outdoortests it is important to be aware of bias introduced bythe choice of location.

Humidity Variations

Atmospheric humidity is very high in Florida,very low in Arizona, and variable in Tennessee.Results obtained at these stations should be indica-tive of performance to be expected under comparableconditions of latitude, elevation, temperature, andhumidity throughout the world.[2]

Solar Radiation

Weathering conditions are more severe inArizona and Florida than in Tennessee, and generallymore severe in Arizona than in Florida. Solar radia-tion in Phoenix averages more than 185,000 langleysper year on a horizontal surface; the average daytimehigh temperature exceeds 38◦C (100◦F) during thesummer months.[2]

Conditions for Reproducing Natural Weathering Stresses in the Laboratory

UV Conditions Water ConditionsQuality UV-B emission with minimal Condensed from vapor phase;

emission below 290 nm pH approximately 4.0–6.0;saturated with O2

Exposure Duration No theoretical maximum or Time and temperature interact;minimum; practical minimum practical limits of four to twenty hoursof three to four hours

Temperature 55◦C–80◦C as required to 60◦C sometimes causes abnormal effects;duplicate service temperature 50◦C for eight hours can cause problems;

40◦C is safe but slower

Sample Mounting Direction

Experimental weathering is done in an openlocation with the samples facing south and inclinednorthward at an angle of 45◦ from the vertical,exposing the specimens to almost the maximum pos-sible sunshine with a fixed mounting in the centralnorthern latitudes. (This mounting is specified inTest Method D1435 published by theAmerican Soci-ety for Testing and Materials.) Less severe exposurewould increase the life expectancy of the materialover that indicated by the test results. For example,a meter cover mounted on the east wall of a housemight receive less than half the available sunshine,and its useful life should be substantially longer thanthat of a test specimen. Differences in weatheringdue to different mounting directions are accentuatedby the fact that the rays of the midday sun containmuch more energy than the early morning and lateafternoon rays.[2]

Artificial Accelerated Tests

Artificial weathering devices, tests that use artifi-cial light sources, are used to measure the resistanceof materials to weather degradation. These tests pro-vide reliable data in a shorter period of time thanoutdoor testing. Light sources for the acceleratedtests include filtered long arc xenon, fluorescentmetal halide lamps, and carbon arc. Less commonlyused light sources include mercury vapor and tung-sten lamps. Each light source has its own inherentbenefits of which a weathering experimenter mustbe aware.

10 The Effects of UV Light and Weather on Plastics and Elastomers

Xenon Arc

Xenon arc is a precision gas discharge lampsealed in a quartz tube. Through a combination offilters used to reduce unwanted radiation, the xenon(long) arc simulates UV and visible solar radiationmore closely than any other artificial light source.It is widely preferred as a light source when thematerial to be tested will be exposed to naturalsunlight.[8]

Automotive test SAE J1885 is used for testinginterior automotive materials and calls for xenon arcexposure with quartz inner and borosilicate outerfilters. This filter combination transmits short-waveUV radiation as low as 275 nm.

Automotive test SAE J1960 is used to eval-uate exterior automotive materials by acceleratedmeans. The test uses a quartz/borosilicate-S filtercombination. Most engineers involved with this teststate that 2500 kJ/m2 is approximately two years ofFlorida testing. However, the spectral power distri-bution (light intensity vs. wavelength) of the SAEJ1960 test method does not exactly match actualMiami sunlight and can be a nonpredictive test forsome materials. Some automotive companies usedifferent optical filter combinations (Boro-S/Boro-Sor CIRA/Soda Lime) that more closely match trueMiami solar radiation. In addition, the compari-son based on a single factor (solar radiant energy)does not take into account the other weatheringfactors such as heat, moisture, etc., and their syn-ergistic effects, which magnify the effects of solarradiation.[8]

Test methods specifying xenon arc includeASTM D2565, D4459, and G155, SAE J1885 andSAE J1960, and GE Co. Highly Accelerated Weath-ering Protocol for all outdoor applications.

Fluorescent or QUV

The QUV test procedure simulates long-termoutdoor exposure to sunlight, rain, and dew byexposing materials to alternating cycles of UV-Aor UV-B light and moisture at controlled elevatedtemperatures. These are the most aggressive compo-nents of weathering—UV radiation, moisture, andheat. UV radiation within a desired UV wavelengthis provided through the use of fluorescent lamps.

Moisture is provided by forced condensation andtemperature is controlled by heaters.[9]

Although UV light makes up only about 5% ofsunlight, it is responsible for most of the damagecaused to durable materials exposed outdoors. Tosimulate the damage caused by UV rays, it is notnecessary to reproduce the entire spectrum of sun-light. In many cases it is only necessary to simulatethe short-wavelength UV.

Each type of lamp differs in the total amount ofUV energy emitted and in its spectrum. FluorescentUV lamps are usually categorized as UV-A or UV-Blamps, depending on the region into which most oftheir output falls.[10]

UV-A lamps are useful for comparing differenttypes of polymers. Because UV-A lamps do not haveany UV output below 295 nm, they do not degradematerials as quickly as UV-B lamps. UV-A lampsusually provide good correlation with actual outdoorweathering.[10]

UVA-340 lamps provide the best possible sim-ulation of sunlight in the critical short wavelengthfrom 365 nm down to the solar cutoff of 295 nm.It is most useful in comparison tests of differentformulations.[10]

UVA-351 lamps simulate the UV portion of sun-light filtered through window glass. It is most usefulfor simulating interior applications.[10]

UV-B lamps are used for fast, cost-effective test-ing of durable materials. All UV-B lamps emit short-wavelength UV below the solar cutoff of 295 nm.Although this short-wave UV accelerates testing, itcan sometimes lead to anomalous results.[10]

UVB-313 is the most widely used UV-B lampfor testing very durable applications. It is especiallyuseful to maximize acceleration when testing verydurable applications like automotive coatings androofing materials.[10]

QFS-40 is the original QUV lamp. These lampsare also known as FS-40 or FS-40 UVB. It hasdemonstrated good correlation to outdoor exposuresfor gloss retention on automotive coatings and formaterial integrity of plastics.[10]

Tests using fluorescent lamps are useful for rel-ative rank comparisons between materials underspecific conditions, but the comparison to servicelifetime performance or correlation to outdoor expo-sures may not be valid. The best use of the UV lampsis for general screening tests such as checking for

Test Environments 11

gross formulation errors with an artificially harshexposure.[8]

Test methods specifying the QUV UV-340 lampinclude ASTM D4329 and D4587, ISO 4892, andSAE J2020.

Carbon Arc or Fadeometer

Carbon arc devices generally use two lamps(twin arc). The flame carbon arc is open or enclosed(ECA), encased in a borosilicate glass cover that actsas a filter for low-wavelength radiation. The spec-tral emission of the flame carbon arc, a significantamount of which is below 300 nm, bears little resem-blance to sunlight. The two strong emission bandsof an enclosed carbon arc peak at 358 and 386 nmand are much more intense than natural sunlight.Therefore, carbon arc testing will have a weaker(than actual outdoor) effect on materials that absorbonly short-wavelength radiation. In addition, ECAresults will have a stronger (than actual outdoor)effect on materials that absorb long-wavelength UVand visible light.[8]

Sunshine Carbon Arc provides a better matchto natural sunlight than ECA at longer wavelengths.However, Sunshine Carbon Arc provides more radi-ation at wavelengths below 300 nm than naturalsunlight.[8]

Due to the fact that some materials absorbprimarily short wavelengths and some materialsabsorb primarily longer wavelengths, carbon arclight sources can distort the relative light stabilityof tested materials, especially when compared tosamples exposed to actual solar radiation.[8]

“While good correlation with outdoor exposureshas been reported for some materials whose weath-ering mechanisms are appropriate for these limitedspectrum sources, this technology has largely beenreplaced with fluorescent UV or xenon arc sys-tems.” Carbon arc testing continues to be used totest material durability in some applications.[8]

Test Results

Failures of exposed specimens are measured orrecorded in several different ways including:[11]

• Time-To-Fifth Spot: Clear films showincipient failure by development of

very small random brown spots char-acteristic of UV degradation. The “firstfailure” is recorded as the time to thefifth spot on these clippings. The firstfew spots may appear fortuitous insome cases and unrelated to generalfailure.

• Final Failure: Spotting and accompa-nying embrittlement continue until thefilm loses integrity and tends to tearfrom the rack or until it is completelybrown. This is the “final failure” time.

• Brittleness Temperature: The brittle-ness temperature is measured beforeexposure and then on the samples asthey are received at regular intervalsfrom the exposure site. Measurementsare run up to 22◦C. The ASTM 1790-62 (Masland Cold Crack) method, withthe use of semi-micro specimens, isfollowed in determining brittlenesstemperatures.

• Elongation: Elongation is measured onthe samples before exposure. As thesamples are received from the test-ing site, their elongations are againmeasured.

Notes on Variability inTesting and Results

Similar test methods can yield test results thatvary widely. When comparing results, the usershould take into consideration that factors such as testsites, time of year, pollution counts, and sample con-ditioning, to name a few, can have a huge impact ontest results. For instance, at Florida test sites, resultscan vary widely due to an increase in wetness causedby proximity to a pond or other sources of moistureor dew, or by proximity to woods that shield the dry-ing effects of wind. Another example is variationin sample mounting and its effect on the period ofdegradation. Plywood backed samples, for instance,get much hotter in direct sunlight than unbackedsamples and they are wet for up to twice as long.

The “synergistic” effect of UV radiation withmoisture is an important area in assessing the validity

12 The Effects of UV Light and Weather on Plastics and Elastomers

of accelerated testing and its correlation to the naturalweathering process. Much of the weathering litera-ture focuses on the interaction between morning dewand UV radiation. While it is clear that this effectcan be reproduced in a laboratory situation, it is notclear that it occurs under actual exposure conditions.The situation is reproduced with devices such asUV-CON and EMMAQUA. However, under normaloutdoor exposure, sunlight will probably dry mate-rials before the sun elevation reaches a point whereUV-B is transmitted through the atmosphere. Labo-ratory conditions must be closely matched to actualweathering situations and it is recommended that youcarefully consider your own situation in comparingit to the test conditions and data presented in thisbook.

Color Stability

UV light stability of pre-colored resins is oftennot the same for clear or natural resins. Color stability

depends on many factors, so actual performancewill depend on lighting conditions, length of timeexposed per day, proximity of material to lightsources and windows, choice of color pigments, andother factors.

In general, there are two approaches to lightstabilization. In the conventional method, light sta-bilization is achieved with pigments such as carbonblack and titanium dioxide. If special requirementsare imposed on the material or if a special coloris required, then additional light stabilizers andadditives are required.

When inorganic opacifiers such as titania orcarbon black are used with resins such as PVC,for instance, higher levels will affect processibility,power consumption, and even the lifetime of pro-cessing equipment, due to increased melt viscosity.[5]

Chapter 1

Acrylonitrile-Butadiene-Styrene

Category: Engineering resin.

General Description: Acrylonitrile-butadiene-styrene (ABS) is a thermoplastic styrene copolymerproduced from acrylonitrile, butadiene, and styrene.

• BASF Terluran® is a two-phase poly-mer blend ABS. A continuous phase ofstyrene-acrylonitrile (SAN) copolymergives the materials rigidity, hardness,and heat resistance.[4]

Weathering Properties

When ABS is used for extended periods of timein outdoor locations or under fluorescent light, dis-coloration or distinctive degradation of propertieswill occur. The cause of weathering-related ABSproblems is light-induced degradation of polybuta-diene, and as a result of this, the contribution ofthe rubber to improved impact strength is dimin-ished.This type of degradation is restricted to surfacelayers.[12]

Prolonged exposure to the weather, especiallydirect sunlight, will cause significant changes in boththe appearance and the mechanical properties ofABS plastics. Terluran® is stabilized to inhibit agingcaused by atmospheric oxygen and elevated temper-ature. This stabilization allows Terluran® parts many

years of service life in indoor applications and evenin interior automotive applications where the partsare subjected to considerable UV exposure.[4]

Sunlight and atmospheric oxygen will damagethe butadiene-containing elastomer component ofABS during long-term exposure resulting in yellow-ing and reduced impact strength. Although this pro-cess can be delayed by the use of dark colors or bystabilization, the preferred material for most outdoorapplications is BASF Luran® S, an acrylonitrile-styrene-acrylate (ASA) material, which consider-ably outperforms ABS in weathering resistance.[4]

The effect of exposure to UV radiation on theimpact strength of ASA and ABS were compared.Standard specimens were exposed on one side inthe Xenotest 1200 and tested per DIN 53453 impacttest with a blow struck on the unexposed side. TheABS specimens suffered a very rapid drop in impactstrength. The ASA specimen retained its impactstrength under these conditions over a longer periodof time, about seven times as long.[13]

Stabilization

Because of its butadiene component, ABSrequires UV stabilizers. Synergistic combinations ofbenzotriazoles (UV absorbers) and hindered aminelight stabilizers (HALS) provide improved lightstability.[14]

14 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 1-1. Outdoor Weathering of White ABS in Florida

Table 1-2. Outdoor Weathering of ABS in Ludwigshafen, Germany

1: Acrylonitrile-Butadiene-Styrene 15

Table 1-3. Accelerated Indoor Exposure of GE Plastics Cycolac® VW300 ABS by HPUV

Table 1-4. Accelerated Indoor Exposure of GE Plastics Cycolac® KJB ABS to Fluorescent Light

16 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 1-1. Changes in Material Characteristics due to Photo-Oxidation of ABS.[12]

Luster

Impact strength

Tensile strength

120

100

80

60

40Det

erio

ratio

n (%

)

20

00 1 2 3

Outdoor Weathering (years)

4 5 6

Note: The depth of the degraded layer brought about by weathering is of the order of several hundred micrometers. Thereaction to photo-oxidation results in the generation of a thin yellow layer at the surface; this layer prevents the diffusionand permeation of oxygen and, in addition, it blocks out light. Accordingly, any further photo-oxidation at the interior of thecomponent is prevented.

Graph 1-2. Outdoor Weathering Exposure Time vs.Yellowness Index of ABS.

1: Acrylonitrile-Butadiene-Styrene 17

Graph 1-3. Arizona Outdoor Weathering Exposure Time vs. Dart Drop Impact Strength of ABS.

Graph 1-4. Arizona Outdoor Weathering Exposure Time vs. Elongation of ABS.

18 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 1-5. Arizona Outdoor Weathering Exposure Time vs. Tensile Strength at Yield of ABS.

Graph 1-6. Arizona Outdoor Weathering Exposure Time vs. �E Color Change of ABS.

1: Acrylonitrile-Butadiene-Styrene 19

Graph 1-7. Arizona, Florida, and Ohio Outdoor Weathering Exposure Time vs. Dart Drop Impact Strengthof ABS.

Graph 1-8. Florida Outdoor Weathering Exposure Time vs. Dart Drop Impact Strength of ABS.

20 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 1-9. Florida Outdoor Weathering Exposure Time vs. Drop Weight Impact of ABS.

Graph 1-10. Florida Outdoor Weathering Exposure Time vs. �E Color Change of ABS.

1: Acrylonitrile-Butadiene-Styrene 21

Graph 1-11. Florida Weathering Exposure Time vs. Chip Impact Strength of ABS (White Rovel Capstock andAcrylic Capstock).

Graph 1-12. Florida Weathering Exposure Time vs. Chip Impact Strength of ABS (Natural Resin).

22 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 1-13. Ohio Outdoor Weathering Exposure Time vs. �E Color Change of ABS.

Graph 1-14. Ohio Outdoor Weathering Exposure Time vs. Dart Drop Impact Strength of ABS.

1: Acrylonitrile-Butadiene-Styrene 23

Graph 1-15. Okinawa, Japan, Outdoor Weathering Exposure Time vs. �E Color Change of ABS.

Graph 1-16. Okinawa, Japan, Outdoor Weathering Exposure Time vs. Dynstat Impact Strength Retainedof ABS.

24 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 1-17. Okinawa, Japan, Outdoor Weathering Exposure Time vs. Elongation at Break Retained of ABS.

Graph 1-18. Okinawa, Japan, Outdoor Weathering Exposure Time vs. Gloss Retained of ABS.

1: Acrylonitrile-Butadiene-Styrene 25

Graph 1-19. West Virginia Outdoor Weathering Exposure Time vs. Falling Dart Impact of ABS at −40◦C.

Graph 1-20. West Virginia Outdoor Weathering Exposure Time vs. Falling Dart Impact of ABS at 23◦C, −25◦C,and −40◦C.

26 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 1-21. West Virginia Outdoor Weathering Exposure Time vs. Falling Dart Impact of ABS at 23◦C.

Graph 1-22. West Virginia Outdoor Weathering Exposure Time vs. Flexural Modulus Retained of ABS.

1: Acrylonitrile-Butadiene-Styrene 27

Graph 1-23. West Virginia Outdoor Weathering Exposure Time vs. Flexural Strength of ABS at −40◦C and23◦C.

Graph 1-24. West Virginia Outdoor Weathering Exposure Time vs. Flexural Strength Retained of ABS.

28 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 1-25. West Virginia Outdoor Weathering Exposure Time vs. Izod Impact Strength Retained of ABS.

Graph 1-26. West Virginia Outdoor Weathering Exposure Time vs. Tensile Strength Retained of ABS.

1: Acrylonitrile-Butadiene-Styrene 29

Graph 1-27. Sunshine Weatherometer Exposure Time vs. Dynstat Impact Strength Retained of ABS.

Graph 1-28. Sunshine Weatherometer Exposure Time vs. Elongation at Break Retained of ABS.

30 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 1-29. Sunshine Weatherometer Exposure Time vs. Gloss Retained of ABS.

Graph 1-30. Weatherometer Exposure Time vs. Impact Strength of ABS.

1: Acrylonitrile-Butadiene-Styrene 31

Graph 1-31. Xenotest 1200 Exposure Time vs. Impact Strength of ABS.

Graph 1-32. Accelerated Indoor UV Exposure Time vs. �E Color Change of ABS.

32 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 1-33. Yellowness Index of UVA- and HALS-Stabilized ABS after Outdoor Weathering in Switzerland.[14]

0

25

20

15

10

5

040

Yel

low

ness

Inde

x

80

Exposure Time (kilolangley)

120

Control

0.25% UVA

0.25% HALS

0.5% UVA0.5% HALS

Chapter 2

Acrylonitrile-Styrene-Acrylate/Acrylonitrile-Butadiene-Styrene Capstock

General Description: GE Plastics’ co-extrusionof Cycolac® acrylonitrile-styrene-acrylate (ASA)and Geloy® acrylonitrile-butadiene-styrene (ABS)resins allows designers, molders, and manufactur-ers to take advantage of the best properties of bothmaterials in a single product.[25]

Weathering Properties by Material Supplier Trade Name

Graph 2-1. Color Change, �E, after Arizona, Florida, and New York Outdoor Weathering of GE PlasticsCycolac®/Geloy® Resin Systems Compared to PVC.[15]

25

20

15

∆E

10

5

0

PVC, White PVC, Brown

C/G, BrownC/G, White

Arizona Florida New York

Weathering Properties

The multilayering technology allows the weatherresistant material to be used as capstock. Capstockis the material used as the additional surface layerapplied to the exterior surface of a profile extrusion.Geloy® resin capstock over a Cycolac® substrateprovides outstanding weatherability.[25]

Chapter 3

Acetal

Category: Thermoplastic.

General Description: Acetal or polyoxymethylene(POM) resins are produced by the polymerizationof purified formaldehyde [CH2O] into bothhomopolymers and copolymers.

• Ticona Celcon®, an acetal copolymer,is a crystalline engineering thermo-plastic product.

• Ticona Hostaform®, an acetal copoly-mer, is a specialty product in the rangeof engineering polymers. HostaformLS grades are used for interior appli-cations in a variety of colors with goodlight fastness and constant mechanicalproperties. Hostaform® black 10/1570is used for exterior applications, and isUV stabilized and impact modified.

• BASF Ultraform® N 2325 U03, anacetal copolymer, is a UV stable injec-tion molding grade developed specif-ically for use in outdoor applications,and is available in black only.

• DuPont Delrin®, an acetal homopoly-mer resin, is a thermoplastic engi-neering polymer manufactured bythe polymerization of formaldehyde.DuPont Delrin® x27 UV includes UVstabilization and is a UV resistantgrade.

Weathering Properties: General

Upon exposure to light, polyacetals that are notUV stabilized display loss of gloss, a change incolor, and in some cases, chalking—the formationof a white coating on the surface. This degradationprocess is accompanied by a decrease in strength.

The wavelength of solar radiation that is harmful topolyacetals is in the range of 290–400 nm.[26]

Damage to the material is triggered by absorp-tion of UV light by the material. In the case ofHostaform®, little direct absorption in the criticalUV region takes place because of the linkages in thepolymer chain. This relatively good UV compatibil-ity of polyacetal is limited, however, by unavoidablesystem-induced impurities and structural irregulari-ties. And in all those cases where other polymers areincorporated [e.g., to improve the impact strength(blends)], the stability is further reduced. In prac-tice, however, these effects are not noticed becauseextremely effective light stabilization systems havebeen developed for Hostaform®.[26]

Improved weathering performance (retention ofsurface appearance as well as mechanical properties)is achieved in the Delrin® x07 series by the use of aselected UV stabilizer package.

Weathering Properties:Colored Material

Colored molded parts show practically no colorchange or no surface changes after accelerated lightexposure tests as per SAE J1885. Parts retain their“new car” appearance and do not show unsightlydeposits or otherwise “chalk” during service lifewhen made from Celcon® UV90Z. Celcon® UV col-ored grades meet standards recently introduced bymajor domestic car manufacturers requiring plasticsin automotive interiors to be free of cadmium-basedcompounds.[27]

Color stability tests using a Xenon ArcWeatherometer to simulate accelerated indoor/outdoor exposure show that pigmented Celcon®

UV90Z significantly outperforms competitive acetaland nonacetal products in resisting color degra-dation, easily passing the automotive SAE J1885

36 The Effects of UV Light and Weather on Plastics and Elastomers

Accelerated Indoor Weathering Test with an aver-age of 0.6 CIELab units color shift (a color shiftof more than +3.0 units fails SAE J1885). Celcon®

UV90Z gave an average 380% lower color changeafter almost five times longer light exposure thanacrylonitrile-butadiene-styrene, and was also supe-rior to polypropylene and polyesters.[27]

Celcon® parts retain a high percentage oftheir original mechanical properties during accel-erated UV aging. After extreme light irradiation of1240.8 kJ/m2, Celcon® UV90Z retains almost 100%of its “as-molded” tensile strength, flex strength, flexmodulus, and impact strength.[27]

Hostaform® S 27072 WS black 10/1570 main-tains very good UV stability during both acceleratedweathering testing (xenon lamp) and outdoor testing(Florida and the Kalahari Desert).[28]

Delrin® 507 BK601 compositions have shownexcellent retention of strength properties after twentyyears of outdoor exposure in Arizona, Florida, andMichigan. Over this period, essentially no loss oftensile strength occurred, but elongation was reducedto about 40% of the initial test value, with the greatestchange in elongation occurring during the first sixmonths of exposure.[29]

For outdoor applications involving intermittentexposure, or a service of one to two years, col-ored Delrin® resins are generally suitable, basedon mechanical property retention, because the col-orant generally offers some UV-screening protec-tion. High levels of carbon black act as an effectiveUV screen and are recommended for noncriticaloutdoor applications.[30]

Delrin® x27 UV family of resins are of spe-cially formulated colors, together with an optimized

UV stabilizer system. Delrin® x27 UV is intendedfor applications where parts are exposed to sunlightthrough glass, which includes automotive interiorcomponents and window hardware.[30]

Even with UV-stabilized color compositions,surface dulling and chalking begin in about 6–8months of exposure in Florida. The chalk may beremoved by hand polishing in the early stages ofdevelopment. If removal is delayed, the chalk layerhardens with time and becomes more difficult toremove.[29]

Weathering Properties:Unpigmented Material

Celcon® M90UV or M270UV is recommendedfor unpigmented, natural, applications. It is whiteas molded, and provides extremely good protectionagainst UV degradation and yellowing.[27]

Weathering Properties:Elevated Air Temperature

Delrin® 500 maintains a tensile strength inexcess of 55 MPa for approximately five years at60◦C. Test bars molded of Delrin® 500 have beenstored for about twenty years in the absence of lightat room temperature. After that time tensile strength,elongation at break, molecular weight, and notchedIzod impact strength were unchanged, and the barsstill retained their luster.[30]

3: Acetal 37

Weathering Properties by Material Supplier Trade Name

Table 3-1. Color Differences, �E, after Light Exposure for Pigmented Ticona Celcon® UV90Z (GM andFord Automotive Colors)

Material Family Acetal, POM

Material Grade Ticona Celcon® UV90Z

Reference Number 27

Exposure Conditions SAE J1885

Exposure Energy 1240.8 kJ/m2

Exposure Time approx. 800 hrs

Features GM Standard GM Garnet GM Very GM Medium Ford CorporateBlack Red Dark Sapphire Beechwood Red

SURFACE AND APPEARANCE

Color Change, �E 0.17 1.00 1.35 0.57 1.50

Table 3-2. Color Differences, �E, after Light Exposure for Pigmented Ticona Celcon® UV90Z

Material Family Acetal, POM

Material Grade Ticona Celcon® UV90Z

Reference Number 27

Exposure Conditions SAE J1885

Exposure Energy 1240.8 kJ/m2

Exposure Time approx. 800 hrs

Features Black Light Red Light Tan Medium Tan Brown

SURFACE AND APPEARANCE

Color Change, �E 0.2 0.2 0.2 0.6 0.2

Features Medium Gray Dark Blue Flame Red Maroon

SURFACE AND APPEARANCE

Color Change, �E 0.3 0.5 0.9 1.2

38 The Effects of UV Light and Weather on Plastics and Elastomers

Table 3-3. Color Differences, �E, after Light Exposure for Unpigmented Ticona Celcon® M90UV

Material Family Acetal, POM

Material Grade Ticona Celcon® M90UV

Reference Number 27

Exposure Conditions Initial Value HPUV Xenon Arc ASTM 4459

Exposure Time 300 HP Units 200 hrs 600 hrs 1000 hrs

SURFACE AND APPEARANCE

Initial b value 4.08

Color Change, �b 2.62 2.63 2.66 2.89

Note: �b is a color value; lower values mean whiter samples.

Table 3-4. Color Differences, �E, after Florida Weathering for Ticona Hostaform® Materials

Material Family Acetal, POM

Material GradeTicona Hostaform®

S 27072 WS 10/1570 C 9021 10/1570 C 9021 LS 10/1570

Reference Number 28

Exposure Conditions Xenotest 1200 CPS (EDAG) VW PV 3920 (Florida)

Exposure Time 1600 hrs

SURFACE AND APPEARANCE

Color Change, �E 1.8 2.4 0.8

Table 3-5. Color Differences, �E, after Xenotest 1200 for Ticona Hostaform® C 9021 LS Blue 80/4065

Material Family Acetal, POM

Material Grade Ticona Hostaform® C 9021 LS Blue 80/4065

Reference Number 26

Exposure Conditions Xenotest 1200

Exposure Time 500 hrs 1000 hrs 1500 hrs 2000 hrs

SURFACE AND APPEARANCE

Color Change, �E 1.2 1.3 1.6 2.2

Note: �E is an approximate value.

3: Acetal 39

Table 3-6. Tensile Strength and Elongation after Arizona Weathering Exposure for DuPont Delrin® 507BK601

Material Family Acetal, POM

Material Grade DuPont Delrin® 507 BK601

Reference Number 29

Exposure Conditions Outdoor Arizona

Exposure Time, years 0 1 2 3 4 10 20

MECHANICAL PROPERTIES

Tensile Strength, MPa 70.3 71.0 71.7 71.0 73.1 69.6 70.2

Elongation, % 20 12 11 9 11 10 8

Table 3-7. Tensile Strength and Elongation after MichiganWeathering Exposure for DuPont Delrin® 507BK601

Material Family Acetal, POM

Material Grade DuPont Delrin® 507 BK601

Reference Number 29

Exposure Conditions Outdoor Michigan

Exposure Time, years 0 1 2 3 4 10 20

MECHANICAL PROPERTIES

Tensile Strength, MPa 70.3 70.3 70.3 70.3 72.4 69.6 64.4

Elongation, % 20 7 13 12 14 10 11

40 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 3-1. Relative Tensile Strength after Accelerated Interior Weathering According to SAE J1885 for DuPontDelrin®.[30]

UV stabilized

1

0.5

00 500 1000

Exposure (kJ/m2)

Rel

ativ

e Te

nsile

Str

engt

h

Standard

Graph 3-2. Relative Gloss after Accelerated Interior Weathering According to SAE J1885 for DuPontDelrin®.[30]

X00 BK

X07 BK

X27UV BK1

0.5

00 500 1000

Rel

ativ

e G

loss

Exposure (kJ/m2)

3: Acetal 41

Graph 3-3. Changes in Mechanical Properties after Light Exposure of Ticona Celcon® UV90Z.[27]

Ten

sile

Str

eng

th

Fle

x S

tren

gth

Fle

x M

od

ulu

s

Izo

d Im

pac

t, N

otc

hed

104.5 100.8

96.7

105.2

100.0

75.0

50.0

25.0

0

Pro

pert

y R

eten

tion

(%)

Mechanical Properties

Note: Total light exposure energy: 1240.8 kJ/m2 (approx. 800 hrs).

Graph 3-4. Outdoor Exposure Time vs. Impact Strength Retained of BASF Ultraform® N 2320 and Ultraform®

N 2325 U Acetal Copolymer.

42 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 3-5. New Jersey and Arizona Outdoor Exposure Time vs. Tensile Impact Strength of Ticona Celcon®

M90 and UV90 Acetal Copolymer.

Graph 3-6. New Jersey and Arizona Outdoor Exposure Time vs. Tensile Strength at Yield of Ticona Celcon®

M90 Acetal Copolymer.

3: Acetal 43

Graph 3-7. New Jersey Outdoor Exposure Time vs.Tensile Strength at Yield of Ticona Celcon® GC25 A AcetalCopolymer.

Graph 3-8. QUV Exposure Time vs. �E Color Change of Ticona Celcon® Acetal Copolymer.

44 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 3-9. Sunshine Weatherometer Exposure Time vs. Elongation Retained of Mitsubishi Iupital® F20 AcetalCopolymer.

Graph 3-10. Sunshine Weatherometer Exposure Time vs.Tensile Strength Retained of Mitsubishi Iupital® F20Acetal Copolymer.

3: Acetal 45

Graph 3-11. Xenon Arc Weatherometer Exposure Time vs. Relative Gloss of BASF Ultraform® N AcetalCopolymer.

Chapter 4

Acrylonitrile-Styrene-Acrylate

Category: Acrylic, engineering resin.

General Description:Acrylonitrile-styrene-acrylate(ASA) is an acrylonitrile copolymer modified withan acrylate rubber included during the polymeriza-tion stage.

• BASF Luran® S is a styrene-acrylonitrilecopolymer that has been impact modi-fied with acrylic ester rubber.[6]

• GE Plastics’ Geloy® ASA resin isan advanced amorphous terpolymer ofacrylicstyrene-acrylonitrile.[35]

Weathering Properties

Luran® S demonstrates high resistance to weath-ering. A special acrylic ester rubber provides resis-tance to UV radiation and atmospheric oxygen. Thetoughness, as measured by the penetration energyon 2-mm thick disks of Luran® S, is maintainedafter significant exposure to sunshine. TheASA+ PC(polycarbonate) blends and UV-stabilized Luran® Sshow particularly favorable performance.[6]

As a weatherable material, Geloy® resin offersexceptional durability in all kinds of harsh environ-ments. In outdoor applications, Geloy® resins retaintheir color stability under long-term exposure to UV,moisture, heat, cold, and impact.[35]

Degree of Discoloration

The extent of yellowing (�b) of Luran® Supon exposure to sunshine remains low for up to4000 hours. UV-stabilized Luran® S shows partic-ularly strong performance, demonstrating virtuallyno yellowing after 4000 hours of exposure. The verylow level of yellowing of Luran® S after exposureto outdoor weathering is comparable with that ofpolyvinyl chloride, a material whose suitability foroutdoor applications has been proven over manyyears of use.[6]

Luran® S in dark shades displays very little ten-dency towards graying when it is exposed to UVradiation or outdoor weathering and subsequentlybrought into contact with hot water and detergentsolutions, conditions that are common in automotiveapplications.[6]

Dark colored Luran® S formulations have onlya very slight tendency toward graying after weath-ering followed by contact with hot water or soapsolution.[6]

Thermal Resistance

The resistance of Luran® S to the effect ofcontinuous heat has been demonstrated by storageexperiments at 90◦C. A slight decrease in toughnessand a strong resistance to yellowing were detectedover the duration of exposure.[36]

48 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 4-1. Color Properties after Florida (45◦ South Facing) Outdoor Exposure for PigmentedGE Plastics Geloy®

Material Family ASA

Reference Number 35

Features Country Green Siding Pebblestone Siding

EXPOSURE CONDITIONS

Exposure Type Outdoor

Exposure Location 45◦ South Facing Florida

Exposure Time (months) 0 6 12 18 24 0 6 12 18 24

SURFACE AND APPEARANCE

CIELab Color Coordinates and Color Shift (D/2◦)

L 66.2 65.6 65.6 66.1 66.3 62.5 62.3 62.2 62.6 62.4

a −6.8 −6.7 −6.7 −6.7 −6.8 1.4 1.4 1.3 1.4 1.3

b 7.8 7.7 8.3 8.3 8.3 11 10.9 11.3 11.4 11.2

�E 0 0.6 0.8 0.5 0.5 0 0.2 0.4 0.4 0.2

�L 0 −0.6 −0.6 −0.1 −0.1 0 −0.2 −0.3 0.1 −0.1

�a 0 0.1 0.1 0.1 0 0 0 −0.1 0 −0.1

�b 0 −0.1 0.5 0.5 0.5 0 −0.1 0.3 0.4 0.2

Table 4-2. Long-Term Material Performance for GE Plastics Geloy®[25]

Material Property Performance

UV Resistance Outstanding

Color Retention Outstanding

Heat Resistance Outstanding

Thermal Aging Excellent

Note: Assumptions include processing and grade expectations that suggest long-term performance(i.e., chemical resistance, chalking, impact, weatherability, strength retention).

4: Acrylonitrile-Styrene-Acrylate 49

Table 4-3. Yellowness Index after Outdoor Weathering in Ludwigshafen, Germany, for BASF Luran® S776 S ASA Polymer

Graph 4-1. Yellowness Index after Outdoor Exposure for BASF Luran® S 797 and Luran® S 776 ASA Polymer.

50 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 4-2. Color Change, �E, after Outdoor Weathering in Okinawa, Japan, for Mitsubishi Rayon® ASAPolymer.

Graph 4-3. Impact Strength Retained after Outdoor Weathering in Okinawa, Japan, for Mitsubishi Rayon®

ASA Polymer.

4: Acrylonitrile-Styrene-Acrylate 51

Graph 4-4. Elongation at Break Retained after Outdoor Weathering in Okinawa, Japan, for Mitsubishi Rayon®

ASA Polymer.

Graph 4-5. Gloss Retained after Outdoor Weathering in Okinawa, Japan, for Mitsubishi Rayon® ASA Polymer.

52 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 4-6. Impact Strength Retained after Sunshine Weatherometer Exposure for Mitsubishi Rayon® T110and T120 ASA Polymer.

Graph 4-7. Impact Strength Retained after Sunshine Weatherometer Exposure for Mitsubishi Rayon® ASAPolymer.

4: Acrylonitrile-Styrene-Acrylate 53

Graph 4-8. Elongation at Break Retained after Sunshine Weatherometer Exposure for Mitsubishi Rayon® ASAPolymer.

Graph 4-9. Gloss Retained after Sunshine Weatherometer Exposure for Mitsubishi Rayon® T115 and T110ASA Polymer.

54 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 4-10. Gloss Retained after Sunshine Weatherometer Exposure for Mitsubishi Rayon® ASA Polymer.

Graph 4-11. Impact Strength after Weatherometer Exposure for BASF Luran® S ASA Polymer at Different TestTemperatures.

4: Acrylonitrile-Styrene-Acrylate 55

Graph 4-12. Impact Strength after Xenotest 1200 Exposure for BASF Luran® S 797 and Luran® S 776 ASAPolymer.

Graph 4-13. Yellowness Index of ABS, Luran® S, and Blends after Exposure to Sunshine.[6]

35

30

25

20

15

10

5

0

–50 1000 2000 3000 4000

Hours of Exposure to Sunshine

Yel

low

ness

Inde

x ABS or PC + ABS

Luran S (ASA)

Luran S-UV (ASA)

56 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 4-14. Penetration Energy after Exposure to Sunshine on 2-mm Thick Disks of Luran® S 778 T, LuranS® 778 T UV, Luran® S KR 2861/1 C, ABS-UV, and PC + ABS.[6]

70

60

50

40

30

20

10

00 500 1000 1500 2000

Hours of Sunshine

Pen

etra

tion

Ene

rgy

(J)

Luran S KR 2861/1 C

(PC + ABS)

ABS-UV

Luran S 778 T UV

Luran S 778 T

Chapter 5

Acrylic and Acrylic Copolymer

Category: Acrylic thermoplastic.

General Description: Polymethyl methacrylate(PMMA) is often just called “acrylic.” PMMA isthe synthetic polymer of methyl methacrylate andis amorphous, transparent, and colorless.

• Atoglas Plexiglas®

• Cyro Acrylite®

• Novacor NAS® 36 and Zylar® 533 areclear, UV-stabilized resins for indoorapplications

• Lucite®

Many acrylic materials are offered as “cap-stock” materials that are extruded over a traditionalsubstrate material such as polyvinyl chloride. Thecombination provides exceptional durability and per-formance characteristics including UV weatheringto the siding or other substrate.

Weathering Properties

The weatherability of the Acrylite® GP F acrylicsheet, Acrylite® GP FL acrylic sheet, and Acrylite®

GP FL W acrylic sheet was evaluated using a XenonArc Accelerated Weathering System. Test sampleswere compared to an unexposed sample at intervalsof 1000, 2000, 3000, and 5000 hours. These expo-sures are approximately comparable to 1, 2, 3, and5 years of Florida outdoor exposure. Both the edgeand the surface colors were evaluated. Estimates ofthe number of years of Florida outdoor weatheringexposure required for the material to undergo sig-nificant changes in color or edge appearance aregiven below.[37]

Plexiglas® V-series of acrylic resins provideoptical clarity and resistance to UV-light degrada-tion and discoloration. Plexiglas® V825 and V920series resins remain virtually unchanged after long-term outdoor exposure. Plexiglas® DR resin providesoutstanding transparency and UV resistance duringlong-term outdoor exposure.[38]

NAS® 36 and Zylar® 533 have been tested forresistance to indoor light exposure according to theconditions of ASTM D4459-99. These results indi-cate that NAS® 36 is very well suited for indoorapplications. It retains its water-white color andsparkling clarity for extended periods of time undermost indoor lighting environments. NAS® 36 hasbetter color stability than many stabilized poly-carbonates. Zylar® 533 has color stability similar tostabilized polycarbonates.[38]

58 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 5-1. Cyro Acrylite® GP F Acrylic Sheet after Xenon Arc Accelerated Weathering

Material Family Acrylic, PMMA

Material Grade Acrylite® GP F

Reference Number 37

Exposure Conditions Xenon Arc Accelerated Weathering System

Features Red 2149-4 Orange 3141-5 Green 564-9

Number of years of Florida outdoor weathering exposure required for the material to undergo significant changes incolor or edge appearance

Years 3–4 1–2 0.5

Table 5-2. Cyro Acrylite® GP FL Acrylic Sheet after Xenon Arc Accelerated Weathering

Material Family Acrylic, PMMA

Material Grade Acrylite® GP FL

Reference Number 37

Exposure Conditions Xenon Arc Accelerated Weathering System

Features Red 2149-4 Orange 3105-5

Number of years of Florida outdoor weathering exposure required for the material to undergo significant changes incolor or edge appearance

Years 5 3

Table 5-3. Cyro Acrylite® GP FLW Acrylic Sheet after Xenon Arc Accelerated Weathering

Material Family Acrylic, PMMA

Material Grade Acrylite® GP FLW

Reference Number 37

Exposure Conditions Xenon Arc Accelerated Weathering System

Features Red Dark Red Orange Yellow Green Blue2130-2 2135-1 3127-2 4073-8 5143-8 6157-9

Number of years of Florida outdoor weathering exposure required for the material to undergo significant changes incolor or edge appearance

Years 5 1–2 3 1–2 0.5 3

5: Acrylic and Acrylic Copolymer 59

Graph 5-1. Light Transmission for Acrylic, Cyrolon® UVP Polycarbonate Sheet, and Polycarbonate afterWeathering Exposure* as per ASTM D1003.[39]

94

91

88

850 1 2 3 5

Years Equivalent

Per

cent

age

Tra

nsm

issi

on

Light Transmission per ASTM D1003

Acrylic

Cyrolon UVP Polycarbonate Sheet

Polycarbonate

*1/8′′ sheet (nominal) EMMAQUA Accelerated Weathered (AZ), DSET Laboratories Inc.

Graph 5-2. Yellowness Index for Acrylic, Cyrolon® UVP Polycarbonate Sheet, and Polycarbonate afterWeathering Exposure* as per ASTM D1925.[39]

12

10

8

6

4

2

0 1 2 3 5

Yel

low

ness

Inde

x

Years EquivalentYellowness Index per ASTM D1925

Polycarbonate

Acrylic

Cyrolon UVP Polycarbonate Sheet

*1/8′′ sheet (nominal) EMMAQUA Accelerated Weathered (AZ), DSET Laboratories Inc.

60 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 5-3. Percentage Haze for Acrylic, Cyrolon® UVP Polycarbonate Sheet, and Polycarbonate afterWeathering Exposure* as per ASTM D1003.[39]

10

8

6

4

2

0 1 2 3 5

Years EquivalentHaze Index per ASTM D1003

Per

cent

age

Haz

e

Acrylic

Cyrolon UVPPolycarbonate

Sheet

Polycarbonate

*1/8′′ sheet (nominal) EMMAQUA Accelerated Weathered (AZ), DSET Laboratories Inc.

5: Acrylic and Acrylic Copolymer 61

Graph 5-4. Luminous Transmittance, Haze, Yellowness Index, and Surface Gloss of Plexiglas® V825 afterFlorida and Arizona Weathering.[38]

95.0

92.0

89.0

86.0

83.0

80.00 1 2 3 5

Florida

Arizona

Luminous Transmittance%

Tra

nsm

ittan

ceA

ST

M D

1003

Years

20.0

15.0

10.0

5.0

0.00 1 2 3 5

Florida

Arizona

Haze

% H

aze

AS

TM

D10

03

Years

10.0

9.0

8.0

7.0

6.0

5.0

4.0

3.0

2.0

1.0

0.00 1 2 3 5

Florida

Arizona

Yellowness Index

Years

Yel

low

ness

Inde

xA

ST

M D

1925

Florida

Arizona

Surface Gloss100

95

90

85

80

75

70

65

60

55

500 1 2 3 5

60°

Spe

cula

r G

loss

AS

TM

D52

3

Years

62 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 5-5. Luminous Transmittance, Haze, Yellowness Index, and Surface Gloss of Plexiglas® DR101 afterFlorida and Arizona Weathering.[38]

95.0

92.0

89.0

86.0

83.0

80.00 1 2 3 5

Florida

Arizona

Luminous Transmittance%

Tra

nsm

ittan

ceA

ST

M D

1003

Years

20.0

15.0

10.0

5.0

0.00 1 2 3 5

Florida

Arizona

Haze

% H

aze

AS

TM

D10

03

Years

10.0

9.0

8.0

7.0

6.0

5.0

4.0

3.0

2.0

1.0

0.00 1 2 3 5

Florida

Arizona

Yellowness Index

Years

Yel

low

ness

Inde

xA

ST

M D

1925

Florida

Arizona

Surface Gloss100

95

90

85

80

75

70

65

60

55

500 1 2 3 5

60°

Spe

cula

r G

loss

AS

TM

D52

3

Years

5: Acrylic and Acrylic Copolymer 63

Graph 5-6. Luminous Transmittance, Haze, Yellowness Index, and Surface Gloss of Plexiglas® V920 afterFlorida and Arizona Weathering.[38]

95.0

92.0

89.0

86.0

83.0

80.00 1 2 3 5

Florida

Arizona

Luminous Transmittance%

Tra

nsm

ittan

ceA

ST

M D

1003

Years

20.0

15.0

10.0

5.0

0.00 1 2 3 5

Florida

Arizona

Haze

% H

aze

AS

TM

D10

03

Years

10.0

9.0

8.0

7.0

6.0

5.0

4.0

3.0

2.0

1.0

0.00 1 2 3 5

Florida

Arizona

Yellowness Index

Years

Yel

low

ness

Inde

xA

ST

M D

1925

Florida

Arizona

Surface Gloss100

95

90

85

80

75

70

65

60

55

500 1 2 3 5

60°

Spe

cula

r G

loss

AS

TM

D52

3

Years

Graph 5-7. Color Change, �E, after Atlas Weatherometer Exposure of Novacor NAS® 30, NAS® 36, Zylar®

533, and Other Materials.[40]

ASTM D4459 (G155, Cycle #4)

NAS 30

NAS 36

ZYLAR 533

GP PMMA

UV stable PC

5

4

3

2

1

00 150 300 450 600

Xenon Arc Exposure Time (hours)

Col

or C

hang

e (∆

E)

Note: ASTM D4459-99 testing was performed in accordance with Method G155-00a (Table X3.2, Cycle #4) on an AtlasCi65A Weather-Ometer® at a xenon irradiance of 0.30W/m2 and a black panel temperature of 55◦C.

Chapter 6

Acrylic and Polyvinyl ChlorideCoextrusion

Category: Coextrusion and blends.

General Properties: Lucite TufCoat® is used forarchitectural capping (capstock). TufCoat® is liter-ally extruded over a traditional substrate materialsuch as polyvinyl chloride (PVC) to provide excep-tional durability and performance characteristics tothe siding.[41]

Weathering Properties

Halogen-containing polymers (e.g., PVC) arerelatively cheap and readily available materials.Theyhave been used outdoors in buildings and glazing.However, the weatherability (e.g., the light stability)

of halogen-containing polymers is poor, leading torelatively short lifetimes particularly in pigmentedformulations.[42]

Acrylic materials are used in a variety of appli-cations because of their toughness, weatherability,appearance, and stability characteristics. Thus theyare often used as capstock material to provide acoating layer over a substrate thermoplastic mate-rial and provide the advantageous properties ofacrylic compounds to the underlying thermoplasticmaterial.[42]

TufCoat® provides UV weathering resistance toa PVC substrate, which means that manufacturerscan offer a much wider range of color options safein the knowledge that the products will not fade orchange color over time.[41]

Chapter 7

Cellulose Acetate Butyrate

Category: Cellulosics.

General Description: Cellulosics are synthetic plas-tics made from a naturally occurring polymer, cellu-lose, obtained from wood pulp and cotton linters.Cellulose must be chemically modified to produce athermoplastic material. Cellulose acetate butyrate isa cellulose ester.

• Eastman Tenite® butyrate is a plasticproduced from cellulose acetate buty-rate. Various formulations of Ten-ite® butyrate have different degreesof resistance to solar radiation. Themost weather-resistant butyrate formu-lations are typified by Tenite® butyrate465. The most used formulas main-tain material properties for five yearsor more when exposed continuously inArizona and include Tenite® butyrate465, 485, and 513.[2]

Weathering Properties

Cellulose esters, like most polymeric materials,degrade when exposed to weathering. Special out-door formulations may remain useful for at leastfive years outdoors in any part of the continentalUnited States and in other areas of the world withcomparable climates. Cellulose esters can be par-tially protected from the direct chain scission andthe photo-catalyzed oxidation using UV inhibitors orUV stabilizers; protection from oxidation is obtainedwith antioxidants.[2]

The deterioration in cellulosics caused by weath-ering depends on the particular cellulose ester,plasticizer, stabilizer system, wavelength of the inci-dent radiation, total amount of radiation absorbed,temperature of the plastic, atmospheric humidity,

industrial contaminants in the atmosphere, and pos-sibly other factors.[2]

Deterioration of cellulosic plastics caused byweathering first appears as a dulling of the surface.As deterioration proceeds into advanced stages, thesurface crazes and cracks; the formation of each fis-sure exposes the underlying plastic to the action ofthe weather. The onset of surface crazing does notmean the end of the usefulness of Tenite® butyrate.It will still have good tensile strength, elongation,and impact strength. Elongation is one of the bestmethods for determining the toughness of a plastic.A brittle material will break with little elongationand will show a smooth, glassy break. A tough mate-rial will show a ductile break with good elongationbefore breaking occurs.[2]

Actual outdoor performance is the most reliablecriterion by which the outdoor usefulness of a plas-tic can be judged. Eastman’s outdoor weatheringprogram involves the exposure of many hundredsof samples at weathering stations in Kingsport,Tennessee (Lat. 36◦32′ N, Long. 82◦34′W, El.1200 ft); Homestead, Florida (Lat. 26◦38′N, Long.81◦51′W, El. 9 ft); and Phoenix, Arizona (Lat.33◦27′N, Long. 112◦3′W, El. 1080 ft).[2]

Color Retention

Articles made of outdoor types of Tenite®

butyrate in suggested colors should give at leastfive years of service under even the most adverseweather conditions found in the continental UnitedStates. These most adverse conditions representexposure to solar radiation that measures approxi-mately 185,000 langleys per year on a horizontalsurface and are found, in general, south of about35◦N latitude and between about 100◦ and 115◦Wlongitude. Comparable exposure in other parts ofthe world should have similar effects.[2]

68 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Graph 7-1. Tensile Strength at Break after Arizona Weathering for Eastman Tenite® Butyrate.[2]

40

35

30

0 10 20 30 40 50

6,000

5,500

5,000

4,500

4,000

Ten

sile

Str

engt

h (M

Pa)

Exposure Time (months)

Tensile S

trength (psi)

Note: 3.2-mm (0.125-in.) thick specimens of an outdoor type of Tenite® butyrate.[14]

Graph 7-2. Elongation at Break after Arizona Weathering for Eastman Tenite® Butyrate.[2]

50

40

30

20

10

00 10 20 30 40 50

Exposure Time (months)

Elo

ngat

ion

(%)

Black

Clear and Colors

Note: 3.2-mm (0.125-in.) thick specimens of an outdoor type of Tenite® butyrate.

7: Cellulose Acetate Butyrate 69

Graph 7-3. Impact Strength after Weathering for Eastman Tenite® Butyrate.[2]

40

35

30

25

20

15

10

5

01 2 3

0

5

10

15

20

25

30Black

Clear and Colors

Time (years)

Impa

ct S

tren

gth

[J a

t 23°

C (

73°F

)]

Impact S

trength [ft·lbt at 23°C (73°F

)]

Note: 3.2-mm (0.125-in.) thick specimens of an outdoor type of Tenite® butyrate; samples weathered in a vertical positionfacing due south. Testing as per ASTM D3029.

Chapter 8

Fluoropolymers: Overview

The fluorocarbon family is made up of sev-eral branches. By varying the fluorine content ofthe polymer, the balance of mechanical propertiescan be tailored for different end use applications.As the fluorine content of a polymer increases, itsresistance to chemicals and weathering, includingUV resistance, also increases. Mechanical propertiesdeteriorate with increasing fluorine content. Fullyfluorinated polymers include polytetrafluoroethy-lene (PTFE or TFE), fluorinated ethylene propy-lene (FEP), and perfluoroalkoxy (PFA); partiallyfluorinated polymers include polyvinylidene fluo-ride (PVDF), polychlorotrifluoroethylene (PCTFE),ethylene-chlorotrifluoroethylene (ECTFE), ethylene-tetrafluoroethylene (ETFE), and polyvinylfluoride(PVF).

Fluoropolymer Weathering

Due to the unique nature of the carbon–fluorinebond, most traditional fluoropolymers have the abil-ity to withstand continuous outdoor exposure.[43]

In a study of weathering resistance, three par-tially fluorinated polymers (ETFE, PVDF, and PVF)were exposed to UV light in a QUV Weatherometer,Q-Panel Co., at 50◦C. The machine was equippedwith UV lamps producing rays in the wavelengthrange of 313–550 nm. The difference between theresistance of these three fluoroplastics was character-ized by the change in tensile properties as a result ofexposure over time. ETFE had the most resistance inthat break elongation, tensile strength, and modulusdid not change upon exposure. Tensile strength andtensile modulus of PVDF remained constant whileits break elongation decreased.All three properties of

PVF declined. Fluorine content, in addition to molec-ular structure, influences the UV light resistance ofthe fluoropolymer. Deficiencies have been overcomeby incorporating organic absorbers and inorganicabsorbing pigments (e.g., titanium dioxide).[43]

Graph 8-1. Mechanical Properties of PVDF, ETFE,and PVF Films after South Florida Exposure.[43]

2.5

2.0

1.5

1.0

0.5

00 400 800 1200 1600 2000 2400

Irradiation Time (hrs)

Ten

sile

Mod

ulus

(G

Pa)

PVDF

ETFE

PVF

Irradiation Time (hrs)

Ten

sile

Str

engt

h (M

Pa) 100

80

60

40

20

0200 400 1000 1400 1800 2200

PVDFETFE

PVF

Irradiation Time (hrs)

Elo

ngat

ion

(%)

400

300

200

100

00 400 800 1200 1600 2000 2400

PVDF

ETFE

PVF

Chapter 9

Polytetrafluoroethylene (PTFE or TFE)

Category: Fluoropolymer.

General Properties: PTFE is completely unaffectedby outdoor weathering. Studies have shown it to beunaffected even after twenty-five years of exposurein Florida.[44]

• PTFE is also known as DuPont Teflon®

Weathering Properties by Material Supplier Trade Name

Table 9-1. Mechanical Properties of PTFE Film after South Florida Exposure[43]

Tensile Strength (MPa) Break Elongation (%)

Years of ExposureMD TD MD TD

0 45.5 8.5 320 400

10 31.5 14.9 190 390

Property Retention (%) 69 175 59 98

Note: MD, machine direction; TD, transverse direction.

Weathering Properties

The outdoor weatherability of PTFE is due to itsmolecular structure and not as a result of additives.

Chapter 10

Fluorinated Ethylene Propylene (FEP)

Category: Fluoropolymer.

General Properties: FEP films remain essentiallyunchanged after twenty years of outdoor exposurewith no evidence of discoloration, UV degradation,or strength loss. This outstanding performance is dueto the structure of the polymer molecule and is notthe result of chemical additives.[45]

Weathering Properties by Material Supplier Trade Name

Table 10-1. Mechanical Properties after 20-Year South Florida Exposure for Two Thicknesses of FEPFilm[43]

Tensile Strength Break Tensile ModulusFilm

Thickness (µm)Years of

Exposure(MPa) Elongation (%) (MPa)

MD TD MD TD MD TD

50 0 21.4 18.6 270 290 462 407

50 5 20 13.8 365 310 462 407

50 7 20 16.6 290 300 428 434

50 10 18.6 16.6 145 221 428 476

50 15 19.4 15.4 200 190 – –

500 0 21.4 20 470 435 496 538

500 6 20 20 580 575 476 469

500 10 20.7 17.2 515 415 455 503

500 15 25.3 25.7 330 334 – –

500 20 21.1 22.0 292 294 – –

Note: MD, machine direction; TD, transverse direction.

Weathering Properties

Tensile strength, break elongation, and electri-cal properties are essentially unchanged after twentyyears of outdoor exposure in South Florida.[43]

76 The Effects of UV Light and Weather on Plastics and Elastomers

Table 10-2. Tensile Strength and Break Elongation after 20-Year South Florida Exposure for TwoThicknesses of FEP Film[43]

Tensile Strength Break ElongationFilm Thickness

(µm)Years of

Exposure(% of initial retained) (% of initial retained)

MD TD MD TD

50 20 91 84 74 65

500 20 100 110 62 68

Note: MD, machine direction; TD, transverse direction.

Table 10-3. Material Properties (Dielectric Strength, Tensile Strength, Elongation at Break, and MITFlex Life) of FEP Film after South Florida Exposure[43]

Machine Direction Transverse Direction

Tensile Elongation Tensile Elongation MIT Flex LifeLength ofExposure(months)

DielectricStrength(kV/mm) Strength at Break Strength at Break (cycles)

(MPa) (%) (MPa) (%)

0 124 18.0 295 15.9 300 24,000

3 112 18.8 305 16.8 265 16,300

6 132 19.0 310 16.9 300 24,400

12 132 15.9 280 15.0 305 17,400

Note: 75 µm = 0.003 in.

Table 10-4. Material Properties (Tensile Strength and Elongation at Break) of FEP Film after SouthFlorida Exposure[43]

Machine Direction Transverse DirectionLength of

Exposure (months) Tensile Strength Elongation Tensile Strength Elongation(MPa) at Break (%) (MPa) at Break (%)

0 19.9 306 23.9 294

6 21.1 276 18.5 279

12 19.9 285 23.2 305

Note: 250 µm = 0.010 in.

10: Fluorinated Ethylene Propylene (FEP) 77

Table 10-5. Electrical Properties of FEP Film after South Florida Exposure[43]

Length of Dielectric Dielectric Constant Dissipation FactorExposure (months) Strength (kV/mm) (1 kHz) (1 kHz)

0 60 2.3 0.00015

6 82 2.4 0.00035

12 79 2.2 0.0002

Note: 250 µm = 0.010 in.

Graph 10-1. Retention of Tensile Strength and Percentage Elongation after Outdoor Exposure for DuPontFEP Film.[45]

All Film Thicknesses

0 2 4 6 8 10 12 14 16 18

3000 21

140

2000

600

500

400

300

200

100

0

0

Exposure Time (years)

Ten

sile

Str

engt

h(p

si)

Ten

sile

Str

engt

h(M

Pa)

Elo

ngat

ion

(%)

50 µm/20 mils

125–250 µm/5–10 mils

50 µm/2 mils

25 µm/1 mil

Chapter 11

Perfluoroalkoxy (PFA and MFA)

Category: Fluoropolymer.

General Properties: PFA is a semi-crystalline, fullyfluorinated, melt-processable fluoropolymer. PFAresins are copolymers of tetrafluoroethylene withperfluorinated vinyl ethers. MFA is a copolymerof perfluoromethylvinyl ether and tetrafluoroethy-lene. MFA is a class of modified PFA resins thathas lower performance and somewhat lower costcompared to standard PFA. Commercial PFAs aregenerally copolymers of perfluoropropylvinyl etherand tetrafluoroethylene.[46]

Graph 11-1. Color Change, �E, after Carbon Arc Weatherometer Accelerated Weathering (Dew Cycle) forPFA and MFA.[49]

4.5

4

3.5

3

2.5

2

1.5

1

0.5

00 100 200 300 400 500 600 700 800 900 1000

∆E (

CIE

Lab)

Exposure Time (hrs)

PFA MFA

Weathering Properties

PFA is unaffected by long periods of exposure todirect sunlight, wind and rain, and exhaust gases.[47]

The high clarity, low haze structure of MFAfilms provides excellent performance in applicationsrequiring clear films, such as solar collectors and cellculture bags, and in UV sterilization applications.[48]

80 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 11-2. Tensile Strength Retention after Carbon Arc Weatherometer Accelerated Weathering (Dew Cycle)for PFA and MFA.[49]

120

100

80

60

40

20

00 100 200 300 400 500 600 700 800 900 1000

Exposure Time (hrs)

Tens

ile S

tren

gth

Ret

entio

n (%

)

PFA MFA

Graph 11-3. Elongation Retention after Carbon Arc Weatherometer Accelerated Weathering (Dew Cycle) forPFA and MFA.[49]

120

100

80

60

40

20

00 100 200 300 400 500 600 700 800 900 1000

Elo

ngat

ion

Ret

entio

n (%

)

Exposure Time (hrs)

PFA MFA

Chapter 12

Polyvinylidene Fluoride (PVDF)

Category: Fluoropolymer.

General Properties: PVDF has good weatheringproperties.[50] It is insensitive to UV light and doesnot need to be protected. Its insensitivity to UVlight results in remarkable gloss retention even afternatural or accelerated weathering.[51]

PVDF is often used as the topcoat in capstock(a single or multilayer film that protects a plasticsubstrate such as polyvinyl chloride, acrylonitrile-butadiene-styrene, polycarbonate, or polyamide).Because it is completely transparent to UV wave-lengths, PVDF used as topcoats contain UVabsorbers to protect the substrate from damage.PVDF capstock can be formulated to last for as longas 10–30 years.[52]

Weathering Properties

Transparent Arkema Kynar® Films are formu-lated with nonmigrating organic UV absorbers toscreen natural light and protect the substrate fromUV damage.[51]

1. Be 99% opaque (absorbance > 2) upto 400 nm for 2000 hours in the SEPAP12-24∗ accelerated weathering test.

2. Ensure a gloss retention > 80% and acolor shift �E < 2 after 1000 hours inweatherometer accelerated testing∗∗(a typical requirement in automotiveapplications).

∗SEPAP 12-24: Climate chamber equipped with four artificiallamps (mercury vapor: unit power 400 W) with cutoff of UVradiation below 300 nm; samples are continuously exposed with-out water sprinkling; temperature is maintained at 60◦C. Notethat the SEPAP 12-24 test is extremely demanding since the UVexposure is permanent (no night and day cycle).∗∗WOM CI135A: Climate chamber equipped with three artifi-cial lamps (xenon arc: 63 W/m2 between 300 and 400 nm) with

The absorbance at 320 nm can be plotted as afunction of time to visualize the performance ofthe film. It can be seen that a 50-µm thick filmmaintains 99% UV opacity (absorbance > 2) formore than 2000 hours and is still 90% UV opaque(absorbance > 1) after 4000 hours of acceleratedweathering in the SEPAP 12-24 test.[51]

The mechanical properties of Kynar® film aremaintained throughout many years of outdoor expo-sure. Clear films exposed to the sun at a 45◦ anglesouth retained their tensile strengths over a 17-yearperiod. During the first few months of exposure whennormal crystallization takes places, the percentage ofelongation at break decreases to a level that remainsessentially constant with time. In addition, the weath-ered films remain flexible and are capable of beingbent up to 180◦ without cracking.[53]

Arkema Kynar® 500 is a special grade of PVDFresin used by licensed industrial paint manufactur-ers as the base resin in long-life coatings called coilcoatings.[54]

Solvay Solexis Halar® 5000 LG and HG arespecifically designed for solvent-based coatings toprovide improved gloss. The weathering character-istics of Hylar® 5000 coatings lead to excellentperformance for the long term.[42]

Solvay Solexis Halar® 5000 PVDF films arehighly resistant to most environmental conditionsincluding gamma radiation and are essentially trans-parent to UV radiation.[52]

Solvay Solexis Solef ® 11010 and Solef ® 21508are PVDF copolymers.

cutoff of UV radiation below 290 nm; samples are exposed alter-natively to the lamps and sprinkled with water for 18 min every102 min; relative humidity is maintained at 50% and temperatureat 70◦C (dry period).

82 The Effects of UV Light and Weather on Plastics and Elastomers

Table 12-1. Mechanical Properties andYellowness Index after Arizona Outdoor Weathering Exposurefor Solvey Solexis Solef® 11010

Material Family Polyvinylidene fluoride (PVDF)

Material Grade Solvay Solexis Solef® 11010

Reference Number 49

Exposure Conditions Outdoor Arizona

Sample Thickness (µm) 75

Exposure Time (years) 0 0.5 1 6 9

MECHANICAL PROPERTIES

Tensile Impact (kJ/m2) 3410 2796 2318 2707 –

Tensile Strength at Yield (MPa) 21.5 23.3 24.7 24.1 25

Elongation at Yield (%) 21 – – 9.5 10.1

Tensile Strength at Break (MPa) 54 43.7 48.6 55.7 54.3

Elongation at Break (%) 470 374 380 410 416

Elmendorf Tear Strength (N) 2.5 1.5 1.5 3.5 3.1

SURFACE AND APPEARANCE

Yellowness Index 1.9 4.1 3.4 1.2 4.7

Table 12-2. Yellowness Index after QUV Accelerated Weathering Exposure (UV-B 313) for SolveySolexis Solef® 21508

Material Family Polyvinylidene fluoride (PVDF)

Material Grade Solvay Solexis Solef® 21508

Reference Number 49

Exposure Conditions UV-B 313, ASTM D1925

Exposure Time (hrs) 0 200 600 1200 2000 4000

SURFACE AND APPEARANCE

Yellowness Index –0.9 –0.5 –0.5 –0.4 –0.4 –0.3

L* 93.4 93.0 92.9 93.1 93.1 93.0

a* –1.0 –0.9 –0.9 –0.9 –0.9 –0.9

b* –0.1 0.1 0.1 0.1 0.1 0.2

Gloss at 60◦ 116 106 93 101 98 76

*CIE 1976 measured by Hunterlab—D65/10◦.

12: Polyvinylidene Fluoride (PVDF) 83

Table 12-3. Retention of Mechanical Properties after Outdoor Weathering of Arkema Kynar® PVDF Film

Table 12-4. Retention of Mechanical Properties after Xenon Arc Weatherometer Exposure of PVDF

84 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 12-1. Retention of Tensile Strength and Elongation after Miami, Florida, Outdoor Weathering Exposure(45◦ Angle South) for PVDF Film.[49]

120

100

80

60

40

20

00 1 2 3 4 5

Ret

entio

n (%

)

Exposure Time (years)

Retention of Tensile Strength Retention of Elongation

Graph 12-2. Color Change, �E, after Miami, Florida, Outdoor Weathering Exposure (45◦ Angle South) forSolvay Solexis Hylar® 5000 PVDF Pigmented Coatings.[49]

5

4.5

4

3.5

3

2.5

2

1.5

1

0.5

00 1 2 3 4 5 6 7 8 9 10

Aging Time (years)

∆E (

CIE

Lab)

Blue Brown Yellow Green Black

12: Polyvinylidene Fluoride (PVDF) 85

Graph 12-3. Gloss Retention after Miami, Florida, Outdoor Weathering Exposure (45◦ Angle South) for SolvaySolexis Hylar® 5000 PVDF Pigmented Coatings.[49]

120

100

80

60

40

20

00 1 2 3 4 5 6 7 8 9 10

Glo

ss R

eten

tion

(%)

Aging Time (years)

Blue Brown Yellow Green Black

Graph 12-4. Chalk Rating after Florida Exposure (45◦ Angle South) for Commercial White Paints.[56]

10

9

8

7

6

5

4

3

2

1

00 2 4 6 8 10

Exposure Time (years)

Cha

lk R

atin

g

PVDF

Silicone Polyester

Plastisol

Urethane

Acrylic

86 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 12-5. Gloss Retention after Florida Exposure (45◦ Angle South) for Commercial White Paints.[56]

120

100

80

60

40

20

00 2 4 6 8 10

Exposure Time (years)

Glo

ss R

eten

tion

(%)

PVDF

Silicone Polyester

Acrylic

Vinyl Plastisol

Urethane

Chapter 13

Polychlorotrifluoroethylene (PCTFE)

Category: Fluoropolymer.

General Properties: Honeywell Aclar® PCTFEfilms are extremely resistant to UV radiation, astested in a weatherometer with water spray.[57]

Graph 13-1. Elongation Retained in the Machine Direction after Weatherometer Exposure of Honeywell Aclar®

22A and Aclar® 33C PCTFE.

88 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 13-2. Elongation Retained in the Transverse Direction after Weatherometer Exposure of HoneywellAclar® 22A and Aclar® 33C PCTFE.

Graph 13-3. Tensile Strength Retained in the Machine Direction after Weatherometer Exposure of HoneywellAclar® 22A and Aclar® 33C PCTFE.

13: Polychlorotrifluoroethylene (PCTFE) 89

Graph 13-4. Tensile Strength Retained in the Transverse Direction after Weatherometer Exposure of HoneywellAclar® 22A and Aclar® 33C PCTFE.

Chapter 14

Ethylene-chlorotrifluoroethylene (ECTFE)

Category: Fluoropolymer.

General Properties: ECTFE undergoes very littlechange in properties or appearance on outdoor expo-sure to sunlight.

Table 14-1. Accelerated Weathering of Solvay Solexis Halar® ECTFE in a Xenon Arc Weatherometer

Weathering Properties

Solvay Solexis Halar® ECTFE shows no changeafter 1000 hours in a weatherometer.[58]

92 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 14-1. Retention of Tensile Strength and Elongation after Miami, Florida, Outdoor Weathering Exposure(45◦ Angle South) for Solvay Solexis Halar® ECTFE Film.[49]

Ret

entio

n (%

)

Exposure Time (years)

00

20

40

60

80

100

1 2 3 4 5 6 7 8 9

% Retention of Tensile Strength % Retention of Elongation

Graph 14-2. Retention of Tensile Strength and Elongation after QUV Accelerated Weathering Exposure,UVB-313, for Solvay Solexis Halar® ECTFE Film.[49]

Ret

entio

n (%

)

Exposure Time (hrs)

00

20

40

60

80

100

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Retention of Tensile Strength Retention of Elongation

14: Ethylene-chlorotrifluoroethylene (ECTFE) 93

Graph 14-3. Color Change, �E, after QUV Accelerated Weathering Exposure, UVB-313, for Solvay SolexisHalar® ECTFE Film.[49]

00

1

2

3

4

5

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

∆E (

CIE

Lab)

Exposure Time (hrs)

Halar ECTFE Film

Chapter 15

Ethylene-tetrafluoroethylene (ETFE)

Category: Fluoropolymer.

General Properties: ETFE has high weatheringresistance, showing no deterioration or change inproperties as a result of exposure to direct sunlight,wind and rain, and exhaust gases.[58]

Table 15-1. Accelerated Weathering of DuPont Tefzel® 200 ETFE in a Weatherometer

Weathering Properties

Exposure of DuPont Tefzel® 200 for morethan one year in Florida and Michigan has hadno effect.[59] DuPont Tefzel® films have excellentoutdoor weathering performance.[60]

Chapter 16

Polyvinyl Fluoride (PVF)

General Description

• DuPont Tedlar® PVF film• DuPont Tedlar® SP PVF

Weathering Properties

PVF has outstanding weathering properties.[50]Pigmented Tedlar®, when properly laminated to

a variety of substrates, imparts a long service life.[61]DuPont Tedlar® PVF film has excellent resis-

tance to sunlight degradation, stands up well toatmospheric pollutants, and is resistant to acid rainattack and mildew. Most airborne dirt does not adhereto Tedlar® film.[61]

Tedlar® is available as a pigmented or near-colorless, transparent film.The pigmented films offerthe highest level of protection from UV light degra-dation, as the pigments block nearly all UV andvisible light from passing through the film. Thismeans that the materials underneath the film will notbe exposed to high-energy, destructive light.[61]

The transparent films are available in anenhanced UV-screening formula that blocks nearlyall of the UVlight up to 350 nm. These UV-absorbingfilms screen out progressively less UV light at theless harmful, lower energy end of the UV spectrum(350–400 nm) and block very little visible light.[30]Unsupported transparent Tedlar retains at least 50%of its tensile strength after ten years of exposure inFlorida at an angle of 45◦ facing south.[61]

Most colors exhibit no more than five NBSunits (modified Adams color coordinates) of colorchange after twenty years of vertical, US outdoorexposure.[61]

Tedlar® SP films match or exceed the resistanceof high-quality plastic surfacing materials to colorfade and loss of gloss. Color retention of Tedlar® SPfilms is dependent upon the color being tested.[62]

High-gloss Tedlar® SP films have been foundto perform similarly to original equipment manu-facturer basecoat/clearcoat paints for gloss retentionunder xenon arc weathering, and provide superiorgloss retention compared to other high-gloss films,refinish paints, and coextrusions.[62]

98 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 16-1. Percentage of Initial Properties Retained after South Florida Weathering Exposure at an Angle of45◦ Facing South for DuPont Tedlar® PVF Film.[63]

Exposure Time (years)

Elongation

Tensile

10

20

40

60

80

100

2 3 4 5 6

% o

f Ini

tial P

rope

rtie

s R

etai

ned

Graph 16-2. Percentage Gloss Retention after South Florida Weathering Exposure at an Angle of 45◦ FacingSouth for DuPont Tedlar® PVF Film and Pigmented Vinyl Film.[61]

Exposure Time (years)

60°

Glo

ss R

eten

tion

(%)

00

20

40

60

80

100

1 2 3 4 5

TUT10BG3 Tedlar® Film

Pigmented Vinyl

16: Polyvinyl Fluoride (PVF) 99

Graph 16-3. Average Rate of UV Absorber Degradation in Free-Standing DuPontTedlar® PVF Film after FloridaExposure.[61]

100

80

60

40

20

00 2 4 6 8 10

Florida Exposure (years; 45° Angle, Facing South)

Initi

al A

bsor

banc

e at

360

nm

(%

)

Graph 16-4. Color Stability of DuPont Tedlar® PVF Film after Exposure to Atlas Sunshine ArcWeatherometer.[63]

5

4

3

2

1

01000 2000 3000 4000 5000

Exposure Time (hrs)

Col

or S

tabi

lity

Note: Colored films vary slightly in color retention, depending on color.

100 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 16-5. Percentage of Initial Properties Retained after Atlas Sunshine Arc Weatherometer Exposure ofDuPont Tedlar® PVF Film.[63]

100

80

60

40

20

02000 4000 6000 8000

% o

f Ini

tial P

rope

rtie

s R

etai

ned

Exposure Time (hrs)

Tensile

Elongation

Graph 16-6. Typical Color Change Range of a Variety of Pigmented DuPont Tedlar® SP Films after Xenon ArcExposure as per the SAE J1960 Method.[62]

5

4

3

2

1

0

0 1200 2400 3600 4800 6000 7200

∆E (

CIE

94)

Exposure (kJ)

16: Polyvinyl Fluoride (PVF) 101

Graph 16-7. Gloss Retention of Refinish Paint, Gel Coat, and DuPontTedlar® SP Film after Xenon Arc Exposureas per the SAE J1960 Method.[62]

100

80

60

40

20

0

0 600 1200 1800 2400

60°

Glo

ss

Exposure (kJ)

Tedlar® SP FilmGel Coat

Refinish Paint

Graph 16-8. Gloss Retention of Acrylic Film, ASA/AES Copolymer, and DuPont Tedlar® SP Film after XenonArc Exposure as per the SAE J1960 Method.[62]

100

80

60

40

20

0

0 600 1200 1800 2400

60°

Glo

ss

Exposure (kJ)

Tedlar® SP FilmAcrylic Film

ASA/AES Copolymer

Chapter 17

Ionomer

Category: Thermoplastic elastomer (TPE).

General Properties: Ionomers are thermoplasticcopolymers that can be processed like thermoplas-tics and demonstrate mechanical properties likeelastomers or cross-linked polymers.[64]

Weathering Properties

Ionomers have poor weathering resistance andmust be stabilized if they are exposed to sunlight oroutdoor weather.

Outdoor weathering experience has confirmedthe outstanding performance of UV-stabilizedDuPont Surlyn®. Parts containing carbon black havebeen in service and exposed to all types of weather forover ten years with no significant change in physicalintegrity or appearance. Other pigmented parts haveretained their physical integrity and appearance afterfive years of exposure to anArizona environment.[65]

Production samples of automotive exterior trimextrusions coated with clear, UV-stabilized Surlyn®

and clear, UV-stabilized polyvinyl chloride wereexposed side by side in up to 5000 hours of accel-erated weathering tests. Besides the obvious edgein UV stability, Surlyn® ionomer resin requires noliquid plasticizer, and therefore there will be nomigration problems in the finished part.[66]

The most traditional and positive method ofstabilizing ionomers for long-term usage in all-weather environments requires the addition of 0.2%antioxidant and 5% (by weight) of well-dispersed,micrometer-sized carbon black. With this modifica-tion, products made from DuPont Surlyn® have beenin continuous service for over ten years.[65]

The development of technology for stabilizingclear or color-pigmented ionomers is a dynamicprocess. Earlier recommendations, based on theincorporation of antioxidant and UV absorbers, haveproduced pigmented products that still retain their

physical integrity and appearance after five years ofnormal exposure to an Arizona environment.[65]

Subsequent development of newer stabilizersand “energy quencher” additives has led to broaderrecommendations for both clear and pigmented sys-tems. There is no complete, comprehensive systemfor UV protection. However, based on continuedresearch with accelerated testing and evaluation oflong-term Florida exposure, it is possible to presenta series of basic rules that provide an opportunity tocustomize the use of polymer modifiers.[65]

The six basic rules for UV protection in ionomersare:[65]

1. Use zinc type ionomers for a more sta-ble base and long-term performance.

2. It is essential to use antioxidants withall stabilizer systems.

3. Both sodium and zinc type ionomersmay be modified for protection fromoccasional exposure to sunlight (lessthan 200 hours/year).

4. For maximum retention of tensile andimpact properties, a combination ofan antioxidant (UV absorber) and anenergy quencher must be used. In pig-mented parts, this should not presentany limitations in product appearance.However, in clear, transparent appli-cations, the presence of currently rec-ommended UV absorbers may createunacceptable levels of yellowness,depending upon the part thickness.

5. When maximum retention of clar-ity, surface brilliance, and absence ofcolor formation are primary end-useconsiderations, a combination of anantioxidant and an energy quencher isrecommended. In this system, tensileand impact characteristics will decline

104 The Effects of UV Light and Weather on Plastics and Elastomers

to one-third the level of natural gradeproperties.

6. In either of the above cases (4 and 5),addition of 2–10 ppm of Monastralblue or violet (transparent pigment)will neutralize the observation ofslightly yellow tints.

Table 17-1. Physical Properties and Visual Appearance after Florida and Arizona Outdoor Weatheringfor UV-Stabilized DuPont Surlyn® Ionomer

In applications where retention of “water white”clarity is necessary, elimination of the UV absorbercomponent will reduce the yellow coloration. How-ever, tensile properties will degrade to approxi-mately 30% of the original. The use of a maskingagent neutralizes the slight color due to the energyquencher.[65]

17: Ionomer 105

Table 17-2. Physical Properties and Visual Appearance after Accelerated Weathering in an AtlasWeatherometer for Zinc Ion Type UV-Stabilized DuPont Surlyn® Ionomer

106 The Effects of UV Light and Weather on Plastics and Elastomers

Table 17-3. Physical Properties and Visual Appearance after Accelerated Weathering in an AtlasWeatherometer for Zinc Ion Type UV- and Antioxidant-Stabilized, Pigmented DuPont Surlyn® Ionomer

17: Ionomer 107

Table 17-4. Physical Properties and Visual Appearance after Accelerated Weathering in an AtlasWeatherometer for Sodium IonType UV- and Antioxidant-Stabilized, Pigmented DuPont Surlyn® Ionomer

108 The Effects of UV Light and Weather on Plastics and Elastomers

Table 17-5. Physical Properties and Visual Appearance after Accelerated Weathering in a QUVWeatherometer for Zinc Ion Type DuPont Surlyn® Ionomer

Chapter 18

Polyphenylene Oxide

Category: Polyphenylene ether (PPE)/polyphenyl-ene oxide (PPO), polystyrene, thermoplastic.

General Properties: GE Plastics Noryl® engineer-ing thermoplastic resin is based on PPE (made andsold by GE Plastics under the trademark PPO). PPE,a high-heat amorphous polymer, forms a miscible,single-phase blend with polystyrene. This techno-logy, in combination with other additives, providesa family of resins covering a wide range of physicaland thermomechanical properties.[67]

Weathering Resistance

PPO blends have good weathering resistancewhen adequately stabilized, but uncolored gradeswill yellow in UV light. Black grades have the bestUV resistance.[68]

Noryl® resins should not degrade, decompose,chalk, craze, or crack on exposure to outdoorweathering.[69]

Noryl® resins will:[69]

1. Lose some impact and elongation(20–40%) strength depending on grade.

2. Gain tensile and flexural strength(5–15%) on long-term exposure.

3. Lose any surface gloss within a fewmonths and become dull.

4. Change to a shade of color which ismore yellow or darker on exposure.

Only surface discoloration will occur. However,very thin sections (under 12.7 mm) may becomemore brittle. This brittleness occurs because the sur-face layers which are losing impact strength andbecoming stiffer make up a proportionately largervolume of a thin section than a thicker section.[70]

When exposed to outdoor light, parts of Noryl®

resin undergo a color change with a tendency todarken slightly and drift toward yellow. When select-ing Noryl® resins for outdoor use, dark colors—black and brown—are recommended, as well asreds, yellows, and oranges, which show excellentcolor stability and where the tendency to yellow ismasked.[70]

110 The Effects of UV Light and Weather on Plastics and Elastomers

Table 18-1. Change in Yellowness Index and Percentage Gloss Retained after Outdoor WeatheringExposure in Arizona, Florida, and New York for GE Plastics Noryl® Modified PPO

Graph 18-1. Change in Color, �E, after Accelerated Indoor UV Exposure of Modified PPO.

18: Polyphenylene Oxide 111

Graph 18-2. Dart Drop Impact Strength after Arizona Outdoor Weathering Exposure of Modified PPO.

Graph 18-3. Percentage Elongation after Arizona Outdoor Weathering Exposure of Modified PPO.

112 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 18-4. Tensile Strength after Arizona Outdoor Weathering Exposure of Modified PPO.

Graph 18-5. Change in Color, �E, after Arizona Outdoor Weathering Exposure of Modified PPO.

18: Polyphenylene Oxide 113

Graph 18-6. Change in Color, �E, after Ohio Outdoor Weathering Exposure of Modified PPO.

Graph 18-7. Dart Drop Impact Strength after Ohio Outdoor Weathering Exposure of Modified PPO.

Chapter 19

Nylon: Overview

Category: Engineering resins, polyamide (PA).

General Properties: Nylon is the common name forhigh-molecular weight PAs—semi-crystalline poly-mers typically produced by the condensation of adiacid and a diamine. There are several types ofnylon; the numeric suffixes refer to the numberof carbon atoms present in the molecular structuresof the amine and acid, respectively, or a single suf-fix if the amine and acid groups are part of thesame molecule. Nylons also differ structurally inthe way the polymer chains are able to align andbond together. Amorphous grades of nylon are alsoavailable.

The most widely used types are nylon 6 (PA6)and nylon 6,6 (PA6,6).

Weathering Properties: General

Nylons are sensitive to UV radiation. Nylons findapplications as engineering plastics as well as fibermaterials. During normal use they are often exposedto sunlight, which causes extensive degradation ofthe polymer. Weatherability will be reduced unlessUV stabilizers are incorporated into the formulation.Carbon black is the most commonly used UVstabilizer. Carbon black lowers the ductility andtoughness as a trade-off for UV stability.[71]

Weathering Properties:UV Stabilization

Honeywell offers a UV-stabilized nylon witha synergistic combination of additives—a reactivesiloxane, a hindered amine, and a phosphite. Thispackage offers a significant improvement in theUV stabilization of nylon resins. Nylon materialsproduced with this stabilizer system maintain theirappearance upon weathering and are highly use-ful for a wide variety of structural and decorativearticles.[72]

Weathering Properties:Colored Material

Dyes are commonly used to add color to nylon.A key component of dye lightfastness is the type ofdye chosen. Acidic and basic dyes react with thenylon molecule while disperse dyes are physicallyentrapped.

Chapter 20

Nylon 6

Category: Polyamide 6 (PA6).

General Properties: BASF Ultramid® nylon 6resins are high strength and stiffness moldingcompounds.

Weathering Properties

Many Ultramid® resins are suitable for outdoorapplications. The unreinforced stabilized Ultramid®

resins (i.e., those with the letters K and H inthe nomenclature type) are extremely resistant toweathering, even if they are uncolored. The outdoorperformance can be further improved by the use ofsuitable pigments, the best effects being achievedwith carbon black. For instance, seats that have beenproduced from Ultramid® B3K and B35K containing

special UV stabilizers and have been exposed formore than ten years in an open-air stadium haveremained unbreakable, and their appearance hasundergone hardly any change.[73]

Thin articles for outdoor use should be producedfrom Ultramid® resins with a high carbon blackcontent (e.g., the Black 20590 and 20592 types)to ensure that their strength remains undiminished.Moldings with a high proportion of carbon black canalso withstand several years of exposure to tropicalconditions.[73]

Housings for automobile rear-view mirrors areexamples of articles that must remain attractivefor many years. In this type of application, thebest results have been obtained with products con-taining special UV stabilizers and products with ahigh carbon black content (e.g., Ultramid® B35EG3Black 20590).[73]

118 The Effects of UV Light and Weather on Plastics and Elastomers

Table 20-1. Mechanical Properties Retained after Outdoor Weathering Exposure in Florida for BASFCapron® Nylon 6

20: Nylon 6 119

Table 20-2. Mechanical Properties Retained after Outdoor Weathering Exposure in California andPennsylvania for LNP Engineering Plastics® Nylon 6

Graph 20-1. Elongation at Break after Outdoor Exposure for Ube Ube® Nylon 6.

120 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 20-2. Flexural Modulus after Outdoor Exposure for Ube Ube® Nylon 6.

Graph 20-3. Notched Izod Impact Strength after Outdoor Exposure for Ube Ube® Nylon 6.

20: Nylon 6 121

Graph 20-4. Tensile Strength after Outdoor Exposure for Ube Ube® Nylon 6.

Graph 20-5. Flexural Strength at Break after Outdoor Exposure in Hiratsuka, Japan, for Nylon 6.

122 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 20-6. Flexural Modulus after Outdoor Exposure in Hiratsuka, Japan, for Nylon 6.

Graph 20-7. Notched Izod Impact Strength after Outdoor Exposure in Hiratsuka, Japan, for Nylon 6.

20: Nylon 6 123

Graph 20-8. Weight Change after Outdoor Exposure in Hiratsuka, Japan, for Nylon 6.

Graph 20-9. Flexural Strength after Outdoor Exposure in Hiratsuka, Japan, for Nylon 6.

124 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 20-10. Tensile Strength after Outdoor Exposure in Hiratsuka, Japan, for Nylon 6.

Graph 20-11. Elongation after Sunshine Weatherometer Exposure of Nylon 6.

20: Nylon 6 125

Graph 20-12. Tensile Strength after Sunshine Weatherometer Exposure of Nylon 6.

Chapter 21

Nylon 12

Category: Polyamide 12 (PA12), thermoplastic.

General Properties: EMS Grivory Grilamid® TRgrades are transparent, thermoplastic polyamidesbased on aliphatic, cycloaliphatic, and aromaticblocks. Due to their composition, Grilamid TRgrades combine the excellent properties of semi-crystalline polyamide twelve types with those of anamorphous thermoplastic in a unique way.[79]

• Grilamid® TR 55• Grilamid® TR 55 LX• Grilamid® TR 55 LY is characterized

by its good chemical and stress-crackresistance.

• Grilamid® TR 90 is characterized byits extremely good UV resistance, highchemical and stress-crack resistance aswell as high impact strength.

• Grilamid® TR 90 UV is a water-cleartransparent polyamide with outstand-ing weathering stability and excellentchemical resistance.

Weathering Properties

Grilamid® TR 55 and TR 55 UV test plaqueshave been exposed for 40 months in southeast

Switzerland at 45◦, facing south. UnstabilizedGrilamid® TR 55 retained good transparency, butdisplayed some discoloration after 4 months ofexposure and some brittleness after 25 months.[80]

In contrast, Grilamid® TR 55 UV maintainedits transparency with no brittleness, surface crazingor degradation, and no effect on relative viscosity.A small increase in yellowness occurred for up toeleven months of exposure and then showed no fur-ther increase. This compares very favorably witha typical stabilized polycarbonate in the same test,which showed significant loss of molecular weightand an increase in yellowness that seriously impairedtransparency.[80]

Samples of Grilamid® TR 55 and TR 55 UVwere tested in an Atlas weatherometer, in cycles of20 minutes (17 minutes of UV exposure followedby 3 minutes of UV exposure plus water spray).After 2000 hours, Grilamid® TR 55 UV showedno measurable change in color or surface appear-ance. In contrast, the unstabilized Grilamid® TR 55,while retaining transparency, showed an increase inyellowness and a slightly matte surface—a behaviorsimilar to unstabilized polycarbonate.[80]

128 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 21-1. Change in Color, �E, after Weatherometer Exposure of EMS Grilamid® TR 55, TR 55 LX, TR 90,and TR 90 UV Nylon 12 Compared to Other Polymers.[81]

00

5

10

15

20

500 1000 1500

Exposure Time (hrs)

∆E/1

mm

2000 2500 3000

TR 55 LX

PA 3-6-T

TR 55

PA PACM12

PC UV

TR 90

TR 90 UV

PMMA

Graph 21-2. Yellow Index (YI) after Weathering Exposure as per ASTM D1975 for EMS Grilamid® TR 90,TR 90 UV, TR 55, and TR 55 LX.[82]

5

10

15

20

25

YI A

ST

M D

1975

00

Exposure Time (hrs)

1000 2000 3000 4000 5000 6000

TR 90

TR 90 UV

TR 55 LX

TR 55

21: Nylon 12 129

Graph 21-3. Tensile Impact Strength after Weatherometer Exposure for EMS Grilamid® TR 55, TR 55 LX, andTR 55 LY Nylon 12.

Graph 21-4. Tensile Impact Strength after Weatherometer Exposure for EMS Grilamid® TR 90 and TR 90 UVCompared to Other Polymers.[81]

TR 90

TR 90 UV

PA PACM12

PC UV

Tens

ile Im

pact

Str

engt

h (k

J/m

2 )

0

200

400

600

800

1000

Exposure Time (hrs)

500 1000 1500 2000 25000 3000

130 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 21-5. Tensile Impact Strength Half-Life after Weathering for EMS Grilamid® TR 90, TR 90 LX, and TR 90UV Compared to Other Polymers.[81]

>2000

0

PA 3

-6-T

GTR 45

PC

PC UV

TR 90

TR 90

LX

PA P

ACM12

TR 90

UV

PMM

A

Hal

f-Li

fe T

ime

(hrs

)

200400600800

100012001400160018002000

>2000

Graph 21-6. Yield Strength after Weathering Exposure as per ISO 4892-2 for EMS Grilamid® TR 90, TR 90UV, TR 55, and TR 55 LX.[82]

00

10

20

30

40

50

60

70

80

90

100

1000

Exposure Time (hrs)

Yie

ld S

tren

gth

(MP

a)

2000 3000 4000 5000 6000 7000 8000

TR 90

TR 90 UV

TR 55 LX

TR 55

Graph 21-7. Percentage Retention of Yield Strength after Weathering Exposure as per ISO 4892-2 for EMSGrilamid® TR 90, TR 90 UV, TR 55, and TR 55 LX.[82]

00

20

40

60

80

100

120

1000 2000

Exposure Time (hrs)

Yie

ld S

tren

gth

(%)

3000 4000 5000 6000 7000 8000

TR 90

TR 90 UV

TR 55

TR 55 LX

21: Nylon 12 131

Graph 21-8. Percentage Retention of Elongation at Break after Weathering Exposure as per ISO 4892-2 forEMS Grilamid® TR 90, TR 90 UV, TR 55, and TR 55 LX.[82]

00

20

40

60

80

100

120

140

1000

Exposure Time (hrs)

Elo

ngat

ion

at B

reak

(%

)

2000 3000 4000 5000 6000 7000 8000

TR 90

TR 90 UV

TR 55 LX

TR 55

Graph 21-9. Percentage Retention of Work to Break after Weathering Exposure as per ISO 4892-2 for EMSGrilamid® TR 90, TR 90 UV, and TR 55 LX.[82]

00

20

40

60

80

100

120

140

160

180

1000 2000 3000 4000 5000 6000 7000 8000

Exposure Time (hrs)

Wor

k to

Bre

ak (

%)

TR 90

TR 90 UV

TR 55 LX

132 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 21-10. Transparency of EMS Grilamid® and EMS Grivory® Compared to Glass and Other Polymers.[81]

50

Grilam

id TR 5

5Grila

mid

TR 90

Grilam

id TR 7

0 LX

Grivor

y GTR 4

5

PC

PMM

A PS

Glass

90 90 8985 87

91 89 90

60

70

80

90

100

Tran

spar

ency

(%

)54

0 nm

, 3 m

m

Graph 21-11. Transparency in the Visible Spectrum of EMS Grilamid® Compared to Other Polymers.[81]

100

80

60

40

20

0200 250 300 350 400 450 500

Wavelength (nm)550 600 650 700 750 800

Tra

nsm

issi

on (

%)

TR 55 TR 90 PMMA PC

Note: Spectrometer LAMBDA 19 UV/VIS/NIR, thickness 2 mm.

Chapter 22

Nylon with Glass Fiber

Category: Polyamide with glass fiber reinforce-ment.

General Properties: Glass fibers can be added toincrease the stiffness of nylon. Because materialproperties such as elongation and impact strengthcan be adversely impacted by the addition of glassfibers, a toughener is often included in the productformulation to retain initial elongation and impactstrength.

Fiberglass reinforcement improves the strength,stiffness, dimensional stability, and performance atelevated temperatures of BASF’s Ultramid® nylon.Reinforcement levels of the different grades rangefrom 6% to 63%.

Table 22-1. Material Properties Retained after Outdoor Weathering in California and Pennsylvania forLNP (a Division of GE Plastics) Glass-Reinforced Nylon 610

Weathering Properties

The reinforced Ultramid® resins also give goodoutdoor performance, and the stabilized types (e.g.,Ultramid® B3EG5) can be relied upon to withstandexposure for periods greater than 5 years. Neverthe-less, the constituent glass fibers cause the surface tobe attacked more severely than that of unreinforcedUltramid® articles.As a consequence, the texture andthe hue may undergo a change after comparativelybrief exposure periods. If the glass-reinforced mold-ings remain exposed for a number of years, erosionto a depth of a few tenths of a millimeter (0.04 in.)can generally be expected, but experience has shownthat this does not exert any significant effect on themechanical properties.[73]

Chapter 23

Nylon 66

Category: Polyamide 66 (PA66) thermoplastic.

General Properties: DuPont Zytel® nylon 66 poly-mer family is available in glass, mineral, super tough,or unreinforced grades. Zytel® 101 is a generalpurpose unreinforced PA66.

Weathering Properties

Nylon 66 degrades upon exposure to naturaland artificial weathering. This degradation causeschanges in its chemical, physical, and mechanicalproperties. The degree of changes depends on thewavelength of the UV radiation and the atmosphericconditions. Chromophores∗, defects, and impuritiesinitiate the hydroperoxidation∗∗ when nylon poly-mers are exposed to light of higher wavelength (λ =340 nm), whereas at lower wavelength (λ = 254 nm)exposure, direct photoscission occurs, which is inde-pendent of the length of the carbon chain.[84]

Neat (not dyed, not bonded, not stabilized) nylon66 tops the chart for strength retention after ninemonths of exposure in Florida. When natural col-ored fibers were tested for nine months of exposure

∗Chromophore is the light absorbing part of a photopigment.Many natural pigments are based on the quinone chromophore.The ability of a compound to absorb light depends on the pre-sence of certain kinds of structural features (i.e., chromophores).∗∗Hydroperoxidation is the decay of the hydroperoxide radical(R–C–O–O•).

in Florida sunlight, the DuPont type 66-728 nylonshowed the highest percentage of strength retentionwhen compared to nylon 6, polyester, and polypropy-lene. The resistance to UV exposure and weatheringincreases substantially as UV stabilizers, dyestuffs,and bonding agents are added in the manufacturingprocess. Starting with the right raw material is crucialin obtaining long life and durability.[85]

Weathering Properties:Colored Material

Nylon 66 is relatively resistant to fading due tosunlight or atmospheric conditions. Nylon 66 is oftendyed to provide color.A key component of dye light-fastness is the type of dye chosen. The dye diffusionrate for nylon 66 is relatively slow. However, it isdifficult to remove dye from the finished product.Nylon 66 is therefore a relatively lightfast nylon.Nylon 66 is also resilient to the diffusion of othermolecules through the fiber, like ozone and nitrousoxide, which can harm the fiber or dye.[85]

Chapter 24

Nylon 6,6T

Category: Polyamide 6,6, thermoplastic, partlyaromatic polyamide.

General Properties: BASF Ultramid® 6/6T is asemi-crystalline, semi-aromatic nylon 6/6T or 6,6T.

Weathering Properties

The experience gained in the outdoor perfor-mance of Ultramid® A and B applies essentially to

Ultramid® T. However, Ultramid® T is degraded anddiscolored somewhat more rapidly than nylon 66 andnylon 6 when exposed to prolonged UV radiation.[86]

Chapter 25

Nylon MXD6

Category: Aliphatic polyamide.

General Properties: Nylon MXD6 is a crystallinepolyamide resin developed by Mitsubishi Gas Chem-ical Company, Inc, which is produced through thepolycondensation of meta-xylene diamine (MXDA)with adipic acid.

Graph 25-1. Flexural Modulus after Outdoor Exposure in Hiratsuka, Japan, for Mitsubishi Reny® MXD6 Nylon.

140 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 25-2. Notched Izod Impact Strength after Outdoor Weathering Exposure in Hiratsuka, Japan, forMitsubishi Reny® MXD6 Nylon.

Graph 25-3. Flexural Strength after Outdoor Weathering Exposure in Hiratsuka, Japan, for Mitsubishi Reny®

MXD6 Nylon.

25: Nylon MXD6 141

Graph 25-4. Tensile Strength after Outdoor Weathering Exposure in Hiratsuka, Japan, for Mitsubishi Reny®

MXD6 Nylon.

Graph 25-5. Elongation (%) after Sunshine Weatherometer Exposure in Hiratsuka, Japan, for Mitsubishi Reny®

MXD6 Nylon.

142 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 25-6. Tensile Strength after Sunshine Weatherometer Exposure in Hiratsuka, Japan, for MitsubishiReny® MXD6 Nylon.

Chapter 26

Polyarylamide

Category: Filled/reinforced thermoplastic, polyaryl-amide.

General Properties: Solvay Advanced PolymersIXEF® compounds are a family of semi-crystallinepolyarylamide thermoplastics reinforced with glassfibers. IXEF® 1002 contains 30% glass fiber, whileIXEF® 1022 contains 50% glass fiber.

Weathering Properties

Specimens of IXEF® 1002 and IXEF® 1011were exposed to the weather for four years at theHiratsuka Test Station under the following condi-tions: average temperature 23◦C, extremes 0◦C and30◦C; average precipitation = 130 mm per month,extremes 50–200 mm per month; total solar irradi-ance 500 kJ/cm2 per year.[77]

The results obtained on the 3.2 mm specimensshowed:

1. Water absorption of approximately0.8%.

2. An approximate 30% reduction inthe maximum stress, essentially cor-responding to the reversible plasticiza-tion brought about by water.

3. No change in flexural modulus.

The surface of a part made from IXEF® pro-duct is a layer of pure polymer approximately 1 µmthick. This layer allows a very good gloss finishto be obtained. If photo-oxidation occurs, this layerdeteriorates as a result of a change in the roughnessof the surface (e.g., an increase from Ra = 0.15 µmto Ra = 2 µm). If a very small quantity of material(3 mg/m2) undergoes oxidation, it results in a changein the appearance of the surface (gloss and color)without the other properties of the material beingaffected in any way.[77]

When choosing the surface appearance of partslikely to be exposed to UV, it is advisable to avoidexcessively low roughness levels because they willbe affected to a considerable degree by superficialphoto-oxidation.[77]

To date, experience with outdoor IXEF applica-tions has established that the variations in shadesobserved are acceptable for many colors. Someparticularly exacting sectors of the market have verystringent requirements; special IXEF grades maysatisfy these requirements in certain cases.[77]

Flame-resistant grades exhibit variations inshade that are generally unacceptable for lightcolors.[77]

144 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 26-1. Flexural Strength after Outdoor Exposure in Hiratsuka, Japan, for Solvay IXEF® 1002 and IXEF®

1022.

Graph 26-2. Flexural Modulus after Outdoor Exposure in Hiratsuka, Japan, for Solvay IXEF® 1002 and IXEF®

1022.

26: Polyarylamide 145

Graph 26-3. Notched Izod Impact Strength after Outdoor Exposure in Hiratsuka, Japan, for Solvay IXEF® 1002and IXEF® 1022.

Graph 26-4. Weight Change after Outdoor Exposure in Hiratsuka, Japan, for Solvay IXEF® 1002 and IXEF®

1022.

Chapter 27

Polycarbonate

Category: Thermoplastic.

General Properties: Polycarbonate (PC) is an amor-phous thermoplastic with excellent toughness char-acteristics, clarity, and heat deflection properties.With the appropriate UV stabilization, PC can beused in products ranging from automotive parts tosunglasses.[87]

• GE Plastics Lexan® resin is a ‘waterwhite’ material that is naturally trans-parent. It demonstrates light trans-parency close to that of glass and hasa very high refractive index.

• GE Plastics Lexan® SLX resin isa copolymer that has been derivedfrom polyester carbonates and resor-cinol arylates. When exposed to UVlight, the copolymer undergoes a photo-Fries rearrangement and produces anew structure that is inherently a UVscreener, essentially making the resinself-protecting.

• Dow Calibre® resins are availablewith (outdoor applications) and without(indoor applications) UV stabilizationpackages.

Weathering Properties

PC is used in building applications, mainlyas glazing material. “When irradiated with shortwavelength UV-B or UV-C radiation, polycarbon-ates undergo a rearrangement reaction (referred toas photo-Fries rearrangement). At low oxygen lev-els this reaction can yield yellow-colored productssuch as o-dihydroxy-benzophenones. But when irra-diated at longer wavelengths (including solar visible

wavelengths) in the presence of air, polycarbonatesundergo oxidative reactions that result in the for-mation of other yellow products. However, neitherthe detailed mechanisms nor the specific compoundsresponsible for the yellow coloration have been fullyidentified. Monochromatic exposure experiments onthe wavelength sensitivity of several degradationprocesses of bis-phenol A polycarbonates have beenreported recently.”[5]

Lexan® resin may be sensitive to long-termexposure to UV light and weathering. The degreeof sensitivity is very much dependent on the specificgrade, the specified color, and the weathering con-ditions. Lexan® resin is ideally suited to a range ofboth indoor and outdoor applications. UV-stabilizedLexan® resin grades maintain high light transmissionafter prolonged UV exposure and offer good resis-tance to yellowing after prolonged exposure to harshclimatic conditions.[88]

Lexan® resin can be additionally protected forapplications in which they are exposed to criticalenvironments of intense sunlight and high humid-ity. Tailor-made, glass clear, UV cap layers fur-ther improve the weathering resistance of extrudedLexan® sheet. For injection-molded parts a vari-ety of coatings, including a range of GE Siliconehardcoats, enhance weathering, scratch, and abrasionresistance.[88]

Lexan® SLX injection-molding grades, whichare transparent, demonstrate (in laboratory testing)excellent weathering (more than seven years), highlight transmission (>83%), and low haze (<1%),with performance and processing much like standardPC. Depending upon conditions, the SLX materialsoffer five to ten times better gloss, color, and lighttransmission retention than standard UV-stabilizedPC. After a slight initial color shift, the transpar-ent grades of Lexan® SLX resin offer a longerlifetime of UV stability and clarity than traditionalUV-stabilized PC.[89]

148 The Effects of UV Light and Weather on Plastics and Elastomers

One of GE’s most weatherable products isLexan® EXL resin, a copolymer of PC and sili-cone. This material demonstrates excellent retentionof mechanical properties upon outdoor exposure.[90]

Calibre® resins without UV stabilizers passthe accelerated indoor colorfast tests described byASTM D4459, which simulate a three- to five-year exposure in an indoor office environment. ForCalibre® resins tested under these conditions, thechange in color as measured by �E is typically lessthan two units.[91]

For outdoor environments, Calibre® resins areavailable with enhanced weathering resistance.These resins are designated by a 2 or 3 in the lastdigit of the product identification code (e.g., 302 15MFR or 703 15 MFR). The UV-stabilized formula-tions can greatly extend retention of the key physicalproperties.[91]

Light Transmission

The light transmission of transparent Lexan®

resin can be changed if required. Grades such as

Weathering Properties by Material Supplier Trade Name

Table 27-1. Izod Impact and Surface and Appearance Properties after Arizona Outdoor Exposure ofDow Calibre® 300 6 MFR without and with UV Stabilizer

Material Family Polycarbonate

Material Grade Dow Calibre® 300 6 MFR

Reference Number 91

Exposure Conditions Arizona, 45◦ angle facing south

Exposure Time 2 years

Features Without UV Stabilizer With UV Stabilizer

Time 0 6 months 1 year 2 years 0 6 months 1 year 2 years

MECHANICAL PROPERTIES

Izod Impact (ft-lb/in.) 17.6 17.9 1.2 0.6 18.2 17.9 17.7 18.5

SURFACE AND APPEARANCE

Transmittance (%) 89.4 85.8 84.7 82.3 89.6 88.4 88.5 87.3

Haze (%) 1.7 8.2 12.7 19.8 1.6 6.8 9.0 14.8

Yellowness Index Increase 0 +12.3 +15.7 +20.0 0 +2.3 +3.3 +6.1

Lexan® 143R-111 and Lexan® LS2-111 have a built-in UV screen to filter out UV radiation up to 380 nm.Modified grades such as Lexan® OQ4320 resin willfilter UV radiation up to 400 nm, thereby providingadditional sun protection without affecting the trans-mission in the visible region. Special colors providea high light transmission in the infrared region only,which blocks all light in the visible light region forapplications such as remote control panels.[88]

Weathering Properties:UV Stabilization

Tinuvin® 234, a benzotriazole UV absorber, iswell adapted to the UV stabilization of PC due to itslow volatility, good initial color, and compatibilitywith PC. To achieve the highest possible resistanceto fading and weathering, Tinuvin® 1577, a UVabsorber, may be used. This product is particularlyrecommended for use in coextruded PC sheets.[87]

27: Polycarbonate 149

Table 27-2. Mechanical Properties Retained after California and Pennsylvania Outdoor Exposure of LNPEngineering Plastics PC

150 The Effects of UV Light and Weather on Plastics and Elastomers

Table 27-3. Mechanical Properties and Surface and Appearance Properties after Arizona AcceleratedOutdoor Weathering and Kentucky Outdoor Weathering for GE Lexan® S-100 and Lexan® 100 Sheet

27: Polycarbonate 151

Table 27-4. Mechanical Properties Retained after XW Accelerated Weathering for GE Lexan® 303

Table 27-5. Change in Color, �E, after Accelerated Indoor Exposure of GE Lexan® 920A by HPUV

152 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 27-1. Light Transmission of UV-Stabilized GE Plastics Lexan®.[88]

100

80

60

40

20

00 800 1600

Wavelength (nm)2400 3200

UV Visible Infrared

Ligh

t Tra

nsm

issi

on (

%)

280–315 nmUV-B–middle UV region315–380 nmUV-A–middle UV region380–780 nmvisible light region780–1400 nmnear infrared region1400–3000 nmmiddle infrared region

Graph 27-2. Light Transmission of Transparent GE Plastics Lexan®.[88]

300 400 500 600 700 800 900 1000 1100

Wavelength (nm)

100

80

60

40

20

0

Ligh

t Tra

nsm

issi

on (

%)

UV Visible Infrared

141Rnon-UV stabilized

LS2UV stabilized

OQ4320UV stabilized with

400 nm cutoff

121R“infrared” color

27: Polycarbonate 153

Graph 27-3. Transmittance through Transparent GE Plastics Lexan® after Florida Outdoor Exposure as perASTM G7.[88]

90

80

70

60

500 1 2 3 4 5

Tra

nsm

ittan

ce (

%)

Exposure (years)

UV stabilizednonstabilized

Graph 27-4. Yellowness Index after Florida Outdoor Exposure as per ASTM G7 for GE Plastics Lexan®.[88]

40

30

20

10

00 1 2 3 4 5

Yel

low

ness

Inde

x

Exposure (years)

UV stabilizednonstabilized

Graph 27-5. Haze after Accelerated Outdoor Exposure of Coated and Uncoated Transparent GE PlasticsLexan®.[88]

10

15

5

00 500 1000 1500 2000

Haz

e (%

)

Exposure (years)

Uncoatedcoated

154 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 27-6. Yellowness Index after Accelerated Outdoor Exposure of Coated and Uncoated Transparent GEPlastics Lexan®.[88]

10

15

5

00 500 1000 1500 2000

Yel

low

ness

Inde

x

Exposure (years)

Uncoatedcoated

Graph 27-7. Yellowness Index after Xenon Arc Weathering for GE Plastics Lexan®.[88]

10

8

6

4

2

00 1000 2000 3000 4000 5000 6000 7000 8000 9000

Yel

low

ness

Inde

x

Exposure (kJ/m2)

UV stable PCLexan SLX2431

resin

Graph 27-8. Change in Yellowness Index, �YI, after Whirlygig Accelerated Outdoor Exposure of GE PlasticsLexan®.[88]

40

36

32

28

24

20

16

12

8

4

00 1000 2000 3000 4000 5000 6000 7000 8000 9000

∆YI

Exposure (hrs)

UV stable PCLexan SLX2431

resin

27: Polycarbonate 155

Graph 27-9. Yellowness Index after Kentucky Outdoor Weathering for GE Lexan® S-100 Sheet.

Graph 27-10. Yellowness Index after EMMAQUA Accelerated Arizona Weathering for GE Lexan® S-100 Sheet.

156 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 27-11. Haze (%) after Carbon Arc XW Weathering for GE Lexan® 153.

Graph 27-12. Yellowness Index after Twin Carbon Arc Weathering for GE Lexan® S-100 Sheet.

27: Polycarbonate 157

Graph 27-13. Yellowness Index after Outdoor Weathering for PC Natural and UV Stabilized with Tinuvin® 234Benzotriazole UV Absorber.[87]

30

20

10

00 50 100 150 200 250 300

Control

+ 0.3% Tinuvin 234

Yello

wne

ss In

dex

Exposure (kLy)

Note: ISO 4607, Florida; 2 mm injection-molded plaques.

Graph 27-14. Gloss (20◦) Retention after Xenon Arc Weathering of Twin Wall PC Sheets (10 mm) Stabilizedwith Tinuvin® UV Absorbers.[87]

120

80

40

00 2000 4000 6000 8000 10000

Exposure time (hours)

Glo

ss

Control

3.5% Tinuvin 360

3.5% Tinuvin 1577

Note: Xenon Arc Weathering, ISO 4892-2, Cycle 102/18; 40 µm coextruded film.

Chapter 28

Polycarbonate Blends

Category: Thermoplastic alloys.

General Description: Polycarbonate (PC) is fre-quently blended with polyesters (polyethyleneterephthalate and polybutylene terephthalate) andstyrenics (acrylonitrile-butadiene-styrene (ABS) andacrylonitrile-styrene-acrylate) to modify its proper-ties for a great variety of end uses.[87] GE PlasticsCycoloy® resins are amorphous PC/ABS blends.

Weathering Properties

Cycoloy® resins exhibit excellent UV stability.Slight color change and loss of mechanical propertiescan result after long-term exposure.[94]

Weathering Properties by Material Supplier Trade Name

Graph 28-1. Color Change, �E, of Pigmented GE Plastics Cycoloy® C1100 PC/ABS after Accelerated UVExposure as per SAE J1885 (ATLAS Ci65XW) and DIN75202 (XENON450).[94]

0

1

2

3

4

5

6

7

8

0 50 100 150

Exposure Time (hrs)200 250 300

∆E

SAE J1885DIN75202

Medium GraySAE J1885DIN75202

Ultramarine Blue

Dark GraySAE J1885DIN75202

Weathering Properties:Stabilization

Tinuvin® 234 protects PC blends from the dis-coloration associated with exposure to UV light. Asshown in Graph 28-3, it takes much longer for thesample containing Tinuvin® 234 to reach the samelevel of discoloration as the control sample.[87]

160 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 28-2. Color Change, �E, of Pigmented GE Plastics Cycoloy® C1100 PC/ABS after Accelerated UVExposure as per SAE J1885 (ATLAS Ci65XW) and DIN75202 (XENON450).[94]

00

1

2

3

4

5

6

7

8

400 800Exposure Time (hrs)

1200 1600

Col

or C

hang

e (∆

E o

r gr

ay s

cale

) Black/gray scaleSAE J1960DIN53387

Black/∆ESAE J1960DIN53387

Graph 28-3. Color Development after Xenon Arc Weatherometer Exposure of PC/ABS (50/50) Blend withTinuvin® 234 UV Stabilizer.[87]

0 500

Control

Exposure Time to ∆YI = 5 (hrs)

Xenon Arc Weathering, ISO 4892-2, Cycle 102/18

1000 1500

+ 0.5% Tinuvin 234

Chapter 29

Polybutylene Terephthalate

Category: Thermoplastic polyester.

General Properties: Polybutylene terephthalate(PBT) is a semi-crystalline polyester that providesa good combination of stiffness and toughness andcan withstand continuous service at 120◦C. The mostimportant grades are those reinforced with glass.

• BASF Ultradur®

• Ticona Celanex® PBT is a seriesof semi-crystalline thermoplastic poly-esters based on PBT.[95]

Weathering Properties

PBT end-products suffer from cracking, yellow-ing, loss of gloss, and deterioration of tensile impactproperties when exposed to UV light.[96]

Moldings made from Ultradur® and exposed tothree years of open air weathering in central Europetend to discolor very slightly and their surfacescarcely changes. Mechanical properties such asrigidity, tensile strength, and tear strength are slightlyaffected.After a weathering test for 3600 hours in theXenotest® 1200, the tensile strength retained is 90%

of the initial value. However, elongation at breakis more adversely affected. Based on experience,3600 hours in the Xenotest® 1200 equipment cor-responds to about five to six years of weatheringin open air. Parts for outdoor use should be man-ufactured from black-colored material in order toprevent impairment of strength due to surface attack.Fiber-reinforced PBT grades such as Ultradur® B4040 G4/G6/G10 with outstanding surface qualityand high resistance to UV radiation are suitable forparts that are subject to particularly extreme expo-sure. These grades have outstanding surface qualityand exhibit high resistance to UV radiation.[97]

Results taken after three years of outdoor expo-sure indicate that there is no fundamental changein physical properties. Predictably, black Celanex®

3300 polyester resin exhibits better property reten-tion than natural resins and should therefore beconsidered where long-term outdoor exposure isrequired.[98]

Weathering Properties:Stabilization

Ciba Tinuvin® 234 and Tinuvin® 1577 can offerPBT products high-quality UV protection.[96]

162 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Graph 29-1. Notched Izod Impact Strength after Florida and Arizona Outdoor Weathering for Ticona Celanex®

PBT.

Graph 29-2. Tensile Strength after Florida and Arizona Outdoor Weathering for Ticona Celanex® PBT.

29: Polybutylene Terephthalate 163

Graph 29-3. Flexural Strength at Break after Hiratsuka, Japan, Outdoor Exposure of PBT Polyester.

Graph 29-4. Flexural Modulus after Hiratsuka, Japan, Outdoor Exposure of PBT Polyester.

164 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 29-5. Notched Izod Impact Strength after Hiratsuka, Japan, Outdoor Exposure of PBT Polyester.

Graph 29-6. Weight Change after Hiratsuka, Japan, Outdoor Exposure of PBT Polyester.

29: Polybutylene Terephthalate 165

Graph 29-7. Tensile Strength Retained after Weatherometer Exposure of Ticona Celanex® PBT.

Graph 29-8. Change in Yellowness Index, �YI, after Light Exposure of PBT Injection-Molded Plaques.[96]

00

5

10

20

30

40

50

2000

Exposure Time (hrs)

∆YI

4000 6000 8000 10000

Control

0.05% Tinuvin 234

0.05% Tinuvin1577

Note: Xenon Arc Weathering, ISO 4892-2, Cycle 102/18; 1 mm plaques; base stabilization: 0.10% Irganox® 1010 and 0.40%Irgafos® 168 (Irganox® B 561).

Chapter 30

Polyethylene Terephthalate

Category: Thermoplastic, polyester.

General Description: Polyethylene terephthalate(PET) can be transparent in the amorphous stateor translucent in the semi-crystalline state. PET,also called polyester, refers to any one of a largefamily of synthetic polymers composed of at least85% by weight of an ester of a substituted aromaticcarboxylic acid.

DuPont Rynite® PET thermoplastic polyesterresins contain uniformly dispersed glass fibers ormineral/glass fiber combinations in PET resin thathas been specially formulated for rapid crystalliza-tion during injection molding.[100]

• Rynite® 530 contains 30% glass-reinforced modified PET

• Rynite® 545 contains 45% glass-reinforced modified PET

• Rynite® 935 contains 35% mica/glass-reinforced modified PET

Weathering Properties

Rynite® 530 NC10 and BK503 and Rynite® 545NC10 and BK504 resins have been exposed out-doors in Florida and Arizona facing 45◦ south for

three years. The data for these samples indicate thatthe resins have retained over 72% of their initialtensile strength and over 50% of their initial elon-gation. The compositions containing carbon blackhad higher property retention. After three years, allthe test samples were slightly “etched.”[101]

After 500,000 langleys of exposure in the equato-rial mount with mirrors (EMMA) and EMMA withwater spray (EMMAQUA) environments, Rynite®

530 NC10 and BK503 and Rynite® 545 NC10 andBK504 resins maintained over 90% of their originaltensile strength and 73% of their original elongationproperties. The EMMA and EMMAQUA environ-ments have similar effects on the properties of theRynite® 530 and Rynite® 545 resins. All test speci-mens had reduced gloss levels after exposure. Onan average, samples exposed in Arizona receivedapproximately 150,000 langleys of sunlight per year.These tests correspond to about 3.3 years of naturalweathering in Arizona.[101]

168 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 30-1. Tensile Strength and Elongation Retained after Arizona Outdoor Weathering of DuPontRynite® 545 NC10, Rynite® 545 BK504, and Rynite® 935 BK505

30: Polyethylene Terephthalate 169

Table 30-2. Tensile Strength and Elongation Retained after Arizona Outdoor Weathering of DuPontRynite® 530 NC10 and Rynite® 530 BK503

Table 30-3. Tensile Strength and Elongation Retained after Florida Outdoor Weathering of DuPontRynite® 530 NC10 and Rynite® 530 BK503

170 The Effects of UV Light and Weather on Plastics and Elastomers

Table 30-4. Tensile Strength and Elongation Retained after Florida Outdoor Weathering of DuPontRynite® 545 NC10 and Rynite® 545 BK504

30: Polyethylene Terephthalate 171

Table 30-5. Tensile Strength and Elongation Retained after Arizona EMMA and EMMAQUA Weatheringof DuPont Rynite® 530 NC10, Rynite® 530 BK503, Rynite® 545 NC10, and Rynite® 545 BK504

Graph 30-1. Tensile Strength after Sunshine Weatherometer Exposure of PET.

172 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 30-2. Elongation after Sunshine Weatherometer Exposure of PET.

Chapter 31

Liquid Crystal Polymers

Category: Thermoplastic.

General Properties: Liquid crystal polymers(LCPs) are a unique class of wholly aromaticpolyester polymers that provide high-performanceproperties.[102]

• Ticona Vectra® LCPs are highly crys-talline, thermotropic (melt-orienting)thermoplastics

Weathering Properties

LCP resins exhibit excellent mechanical pro-perty retention after exposure to weathering.[102]

After 2000 hours of artificial weathering, mold-ings made from Vectra® retained more than 90%of their initial mechanical property values. Afterone year of outdoor weathering, a slight whitedeposit was detected. The white deposit is thedegraded material that appears on the surface (chalk-ing) and results in a reduction in gloss, color change,and deterioration of mechanical properties.[103]

174 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 31-1. Mechanical Properties Retained after Xenon Arc Accelerated Weathering for Ticona Vectra®

A950, Vectra® A130, Vectra® B950, and Vectra® A540

Chapter 32

Polyarylate

Category: Thermoplastic.

General Properties: Westlake Ardel® is a trans-parent thermoplastic with a slight yellow tint.

Weathering Properties

Ardel® resins are specifically formulated toendure the damaging effects of UV light. Whenexposed to UV light, this unique material undergoes

molecular rearrangement resulting in the formationof a protective layer that essentially serves as a UVstabilizer. This inherent UV stability combined withsuperior retention of optical and mechanical pro-perties makes polyarylate an ideal choice for anyapplication where weathering effects could pose aproblem.[104]

Chapter 33

Polyimide

Category: Thermoset.

General Properties: DuPont Kapton® is synthe-sized by polymerizing an aromatic dianhydridewith an aromatic diamine. UBE Upilex® R is pro-duced by the polycondensation of biphenyltetracar-boxylic dianhydride and diamine and is meant forgeneral use.

Weathering Properties: General

UV radiation, oxygen, and water have a degrad-ing effect on Kapton® if it is directly exposed. Thiseffect is shown as a loss of elongation when Kapton®

is exposed in Florida test panels. Kapton® also showsa loss of elongation as a function of exposure time

Weathering Properties by Material Supplier Trade Name

Graph 33-1. Ultimate Elongation after Florida Aging of DuPont Kapton® Film.[1]

0500

Exposure Time (hrs)

Ulti

mat

e E

long

atio

n (%

)

1000 1500 2000 2500 3000 3500 4000 4500 5000

20

40

60

80

100

120

in an Atlas weatherometer. Normal room fluores-cent lighting has no noticeable degrading effect onKapton®.[1]

UBE Upimol® R is stable when exposed tosunshine and UV light.[105]

Weathering Properties: OuterSpace and Nuclear Environments

Because of its excellent radiation resistance,Kapton® is frequently used in high radiation envi-ronments where a thin, flexible insulating materialis required. US Government and CERN (EuropeanOrganization for Nuclear Research) data are avail-able from the manufacturer of this product.[1]

178 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 33-2. Ultimate Elongation after Atlas Weatherometer Exposure of DuPont Kapton®.[1]

00

20

40

60

80

100

120

100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900

Exposure Time (hrs)

Ulti

mat

e E

long

atio

n (%

)

2000

Graph 33-3. Elongation Retained after Sunshine Weatherometer Exposure for UBE Upilex® R and UBEUpilex® S.

33: Polyimide 179

Graph 33-4. Flexural Strength Retained after Sunshine Weatherometer Exposure for UBE Upimol® R.

Graph 33-5. Tensile Strength Retained after Sunshine Weatherometer Exposure for UBE Upilex® R and UBEUpilex® S.

180 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 33-6. Flexural Strength Retained after UV-CON Exposure for UBE Upimol® R.

Chapter 34

Polyamideimide

Category: Thermoplastic, engineering resin.

General Properties: Solvay Advanced PolymersTorlon® 4203L polyamideimide resin is an unre-inforced, all-purpose grade, which contains 3%titanium dioxide and 0.5% fluoropolymer.[107]

Weathering Properties

Torlon® molding polymers are exceptionallyresistant to degradation by UV light. Torlon® 4203L

Weathering Properties by Material Supplier Trade Name

Graph 34-1. Elongation after Atlas Sunshine Carbon Arc Weatherometer Exposure for Torlon® 4203L.[107]

100.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

100

4203L

1000 10000

Exposure Time (hrs)

Elo

ngat

ion

(%)

Note: The test conditions included a black panel temperature of 145◦F (63◦C), 50% relative humidity, and an 18-minutewater spray every 102 minutes.

resin does not degrade after 6000 hours of weathero-meter exposure, which is roughly equivalent tofive years of outdoor exposure. The bearing grades,such as 4301, contain graphite powder that rendersthe material black and screens UV radiation. Thesegrades are even more resistant to degradation due tooutdoor exposure.[107]

182 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 34-2. Tensile Strength after Atlas Sunshine Carbon Arc Weatherometer Exposure for Torlon® 4203L.[107]

10000100

5

10

15

20

25

30

100 10000

50

100

150

2004203L

Exposure Time (hours)

Tens

ile S

tren

gth

(kps

i)

Tens

ile S

tren

gth

(MP

a)

Note: The test conditions included a black panel temperature of 145◦F (63◦C), 50% relative humidity, and an 18-minutewater spray every 102 minutes.

Chapter 35

Polyetherimide

Category: Thermoplastic.

General Properties: GE Plastics Ultem® 1000polyetherimide is an amorphous, translucent engi-neering thermoplastic with good rigidity and thermalmechanical strength for demanding applications.[108]

Weathering Properties by Material Supplier Trade Name

Graph 35-1. Tensile Strength after Xenon Arc Weatherometer Exposure of GE Plastics Ultem® 1000.

Weathering Properties

Ultem® resin is inherently resistant to UV radia-tion without the addition of stabilizers. Exposure to1000 hours of xenon arc weatherometer irradiation(0.35W/m2 irradiance at 63◦C) produces a negligiblechange in the tensile strength of the resin.[108]

Chapter 36

Polyetheretherketone (PEEK)

Category: Polyketone, thermoplastic.

General Properties: PEEK, a unique semi-crystalline, high-temperature engineering thermo-plastic, is an excellent material for a wide spectrum ofapplications where thermal, chemical, and combus-tion properties are critical to performance. The addi-tion of glass fiber and carbon fiber reinforcementsenhances the mechanical and thermal properties ofthe basic PEEK material.

Table 36-1. Tensile Strength Retained after United Kingdom Outdoor Weathering Exposure of Natural,Black, and White Pigmented Victrex® PEEK

Weathering Properties

Victrex® PEEK, like most linear polyaromatics,suffers from the effects of UV degradation duringoutdoor weathering. However, testing has shown thiseffect to be minimal over a twelve-month periodfor both natural and pigmented moldings. In moreextreme weathering conditions, painting or pigment-ing will protect the polymer from excessive propertydegradation.[110]

186 The Effects of UV Light and Weather on Plastics and Elastomers

Table 36-2. Tensile Strength Retained after United Kingdom OutdoorWeathering Exposure of PigmentedVictrex® PEEK

Chapter 37

Polyethylene: Overview

General Properties: Polyolefin homopolymers aremade from ethylene, propylene, butylene, andmethyl pentene. Other olefin monomers such as pen-tene and hexene are used to make copolymers. Theprincipal resins of the polyolefin family are poly-ethylene and polypropylene, and polyolefin copoly-mers such as ethylene-vinyl acetate, ionomer,polybutylene, and polymethyl pentene.[111]

Weathering Properties: General

All polyethylene (and polypropylene) resins aresusceptible to degradation upon long-term exposureto sunlight, thereby losing useful tensile properties.Polyethylene films exposed to solar UV-B radia-tion readily lose their tensile strength as well astheir average molecular weight. The mechanismcausing this deterioration is one of “thermooxida-tive or photooxidative degradation rather than ofdirect photolysis, and is catalyzed by the presenceof metal compounds.” The free radical pathwayslead to hydroperoxidation and consequent chainscission.[5]

UV light contains shorter wavelengths than vis-ible light. The shorter the wavelength, the moreenergy it contains and thus the more damage it does.Fluorescent lighting also contains a band of UVlight,but only at an intensity of around 15% of normalsunlight.[112]

Generally, higher density resins, which are com-posed of a larger crystal structure and have lesspotential for entrapping oxygen, provide better UVstability. Although the secondary effect of a lowermelt index (MI), which provides a tougher part andthus longer life to obtain the same absolute breakpoint, is a factor, the MI does not directly affectUV stability. Thus, all things being equal, higherdensity and lower MI polyethylenes enhance UVperformance. Again these factors are generallynegligible.[112]

UV light alters the molecular characteristicsof polyethylene by breaking the carbon-hydrogenbonds and creating free radicals. The free radi-cals then break polyethylene into shorter moleculesresulting in a more brittle polymer. UV light createsa higher MI polyethylene, especially on the exposedsurface area. Degradation can range from mere sur-face discoloration affecting the aesthetic appeal ofa product to extensive loss of mechanical proper-ties that severely limits its performance. This showsup as a reduction in break elongation and impactproperties, typical of higher MI polyethylene. Thesubsequent attachment of oxygen to these brokensites leads to further accelerated degradation andthe formation of oxidized species such as carbonyland carboxyl structures, which are often used asanalytical indicators of UV degradation.[112]

Polyethylene Films

The crucial role of temperature on the weather-ing of polyethylenes was illustrated in a recent studyon desert exposure of polyethylene films.[112] Twosets of polyethylene film samples, one maintainedat 25◦C at all times in an air-cooled, UV-transparentenclosure, and the other left under the much higherambient temperature, were exposed to sunlight out-doors. The air temperature varied in the range 26◦C–36◦C during the period of exposure. However, thesurface temperature of plastics exposed to sunlightwas much higher (by as much as 60◦C for commonplastics depending on the color and the thickness)than that of the surrounding air due to heat buildup.Samples kept at the lower temperature deterioratedmuch slower than those at ambient temperaturealthough both were exposed to the same dose of solarUV radiation. It is the synergistic effect of high tem-perature and solar UV radiation that is responsiblefor the rapid degradation of polyethylene films underthese conditions. The findings are consistent with the

188 The Effects of UV Light and Weather on Plastics and Elastomers

observation that weathering rates of common plas-tics are very much slower when exposed floatingin sea water, in marine environments, compared tothose exposed on land. Water acting as a heat sink isable to maintain low sample temperatures, retardingdeterioration.[112]

Weathering Properties:Color Pigments

Polyethylene is often colored or pigmented. Thechoice of pigment can determine the outdoor per-formance of the polyethylene product. The amount,particle size, and chemical type of pigment, suchas its organic or inorganic nature, can all affect theUV performance. Generally, carbon black tends tobe the best UV performer due to its high absorptionof UV light. Dry blending pigment has a minimaleffect as the dispersion and thus absorption char-acteristics are not sufficient to protect the basepolymer.[112]

It is important not to confuse UV performancewith color-fading problems when dealing with pig-ments. Sometimes, a pigment may fade while thebase polymer remains unaffected by true UV degra-dation. Thus, impact and tensile properties areunaffected while the appearance of the part changes.

Pigments should also be color stable when exposedto weathering. These pigments are generally referredto as UV grade pigments.[112]

Weathering Properties:UV Stabilizers

For many years, polypropylene and polyethy-lene were stabilized against the detrimental effects ofUV radiation using a low-molecular weight hinderedamine light stabilizer (HALS) such as Tinuvin®

770. During the mid- to late-1980s, combinations ofhigh-molecular weight HALSs with low-molecularweight HALSs provided a better balance of UVstability, thermal stability, and substrate compati-bility. Some of the newest products for thick-section polyolefins include Tinuvin®123 S, a solid,non-interacting, low-molecular weight NOR HALS;Chimassorb® 2020, a low volatility, oligomeric high-performance HALS; Tinuvin® 783, Tinuvin® 791,Chimassorb® 2030, and Chimassorb® 2040, newHALSs that exploit mixed HALS synergy; andIrgastab® FS 210, Irgastab® FS 410, Irgastab® FS811, and Irgastab® FS 812, a family of phenol-freestabilizers that perform very well in color criticalapplications.[113]

37: Polyethylene: Overview 189

Weathering Properties by Material Supplier Trade Name

Table 37-1. Service Life after Outdoor Weathering for Cyanox 2777, Cyasorb UV 531, and CyasorbUV-3346 UV-Stabilized Polyethylene Greenhouse Film

190 The Effects of UV Light and Weather on Plastics and Elastomers

Table 37-2. Service Life after Outdoor Weathering for Cyasorb UV-3346 UV-Stabilized PolyethyleneGreenhouse Film

Table 37-3. Mechanical Properties Retained after California and Pennsylvania Outdoor Exposure ofGlass-Reinforced LNP Polyethylene

37: Polyethylene: Overview 191

Graph 37-1. Retention of Elongation after Atlas Weatherometer Exposure of High Density Polyethylene (HDPE)Plaques.[113]

80

60

40

20

0Control Tinuvin

622Tinuvin

783Chimassorb

944

Ret

entio

n of

Elo

ngat

ion

(%)

Note: Sample: 3.125 mm (125 mil) HDPE plaques. Base stabilization: 0.06% Irganox B225. Exposure: 6000 hrs in a AtlasWeatherometer Ci65 @ 65◦C, 0.35 W/m2 at 340 nm.

Graph 37-2. Impact Strength Retained after Atlas Weatherometer Exposure of Linear Low Density Polyethylene(LLDPE) Plaques.[113]

0.2% Tinuvin 783

0.2% Tinuvin 622

0.2% Chimassorb 944

0 20 40 60 80 100

Retained Impact Strength (%)

1000 hrs 6000 hrs 10000 hrs

Note: Sample: 3.125 mm (125 mil) butene-LLDPE plaques, rotomolded at 344◦C (650◦F). Base stabilization: 0.05%Irganox® 1010 + 0.02% DLTDP.

192 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 37-3. Kilolangleys of Exposure to Create 50%Tensile Strength Retained after Arizona Outdoor Exposureof HDPE-Pigmented Samples.[112]

0.25%

0.25%

0.25%

0.25%

0.5%

0.5%

0.5%

0.5%

0.5%

330

230

250

570

210

500

460

230

175

>700*

0 100 200 300 400 500 600 700 800

Arizona (kLy)

Failure Criteria: 50% retainedtensile impact strength.

Phthalocyanine Green

Phthalocyanine Blue

Azo-Red

Organic Yellow(tetrachloroisoindolinone)TiO2 (stabilized, coated Rutile)

Ultramarine Blue

Iron Oxide

Cd-Red

Cd-Yellow

Unpigmented

Note: Polymer: HDPE (Ziegler). Base stabilization: 0.03% Irganox 1076 + 0.05% calcium stearate. Light stabilization:0.15% Tinuvin 770. Polyolefin thick sections, Arizona 45◦ south (start November).Source: Ciba: Stabilization of Polyolefins—Part 2.*No sample left.

Graph 37-4. Tensile Strength after Arizona Exposure of 0.96 Density Unstabilized Polyethylene with VariousPigments.[112]

5000

4000

3000

2000

1000

0

Natural1% Phthalocyanine Blue

1% Phthalocyanine Green

1% Carbon Black

1% Iron Oxide

1% Cadmium Red

1% Cadmium Yellow

1% TiO2 (Rutile)

1% TiO2 (Anatase)

0 6 12 18 24 30 36 40

Months Exposed in Arizona

Ten

sile

Str

engt

h (p

si)

Chapter 38

Low Density Polyethylene

Category: Polyolefin, thermoplastic.

General Properties: Low density polyethylene thatcontains UV stabilizers demonstrates significantly

better UV performance than unstabilized polyethy-lene but shows reduced tensile strength and elonga-tion at break.

Chapter 39

High Density Polyethylene

Category: Polyolefin, thermoplastic.

Weathering Properties:Colored Material

Carbon Black

It has been found that even low levels of carbonblack impart such a high level of protection tothe polymer that no other light stabilizers or UVabsorbers are required. Several theories have beenadvanced to explain this phenomenon. Schonhornand Luongo stated that the photo-oxidative stabiliza-tion of high density polyethylene (HDPE) filled withcarbon black is due not only to the light shieldingcapability of carbon black but also to its moder-ately low surface energy. Another possibility is thatsince the antioxidant properties of surface phenolicgroups on carbon black have been well characterized,increased stability may be obtained by the interrup-tion of chain propagation. Regardless, compoundscontaining 0.5% carbon black have been exposedfor 10,000 hours in a weatherometer with no loss intensile strength.[115]

White Pigments

The weathering resistance of several types ofwhite colorants—zinc oxide, exterior rutile TiO2,and indoor rutile TiO2 as well as anatase TiO2—was compared. In all instances, 2% pigment wasused in combination with 0.5% of a UV absorber.Anatase TiO2 and indoor rutile TiO2 were totallyineffective in protecting HDPE and have poorer per-formance than the natural stabilized resin. However,with exterior grade TiO2 UV protection is somewhatimproved.[115]

Zinc oxide on the other hand, provides excel-lent UV protection to polyethylene. The tensile

strength of the zinc oxide formulation is signif-icantly better than the one containing 2% TiO2.For best weathering results, zinc oxide can beused provided its hiding power is sufficient for theintended application. For high opacity film and thin-walled containers, TiO2 is a better choice, becausethe tint strength of zinc oxide is too low to pro-vide sufficient opacity. Weathering performance ofan exterior grade TiO2, without UV absorber, andat three different pigment concentrations shows thata formulation containing 2% TiO2 has only 50% ofthe weathering resistance of one containing 2% TiO2

with 0.5% hydroxybenzophenone.[115]Such systems can be improved through the

use of nickel and hindered amine light stabilizers(HALSs). Systems with nickel complex light stabi-lizers and HALSs are not significantly affected after2000 hours of weatherometer exposure, as comparedto the formulation containing a hydroxybenzophe-none absorber.[115]

Yellow Pigments

To study the effect of yellow pigments on HDPEweatherability, three pigments were selected andincorporated at a 1% concentration in an ethylene-butene copolymer containing 0.5% of a UV stabi-lizer. The pigments chosen were cadmium yellow,lithopone yellow, and coated molybdate.[115]

After weatherometer exposure for 8000 hours,cadmium yellow had the best performance, followedby coated molybdate, and then lithopone yellow.Increasing the concentration of coated molybdateand lithopone yellow improved the weathering per-formance of the compound, but increasing the cad-mium yellow concentration decreased its overallweathering effectiveness. Since this phenomenonhas been demonstrated repeatedly, an assumptioncan be made that a reaction must occur between thepigment and the stabilizer at higher pigment con-centrations. Apparently, this does not happen, or at

196 The Effects of UV Light and Weather on Plastics and Elastomers

least not as much, with coated molybdate or litho-pone yellow pigment. The result of interaction ofUV absorber and pigment, illustrated by the effectof UV stabilizer on 0.95 density polyethylene resinsystems containing 1% and 2% cadmium yellow pig-ments, show that when no stabilizer is used the 2%system is somewhat better than the 1% cadmium yel-low system. However, in formulations with stabilizerthe opposite effect occurs.[115]

To further study this interaction between stabi-lizers and cadmium yellow in a polyethylene system,samples were prepared containing two nickel com-plexes furnished by two suppliers. These nickelcomplexes are known to perform as light stabili-zers, whereas hydroxybenzophenone was brittleat 10,000 hours of exposure. However, the 2%cadmium yellow system containing both nickelComplex A and B exhibited only a modest decreasein tensile strength after this same exposure period.The HALS would appear to be marginally better thanthe nickel complex but does not exhibit the greencolor inherent with nickel stabilizers. This furtherillustrates the complex interrelationships betweenstabilizers and pigments.[115]

Both lithopone and cadmium yellow will fadeduring extended outdoor exposure. Although thisis not a problem with single-pigment color formu-lations, the color change can be significant whencadmium yellow is combined with a more light sta-ble pigment, such as ultramarine blue, to produce agreen color.[115]

Red Pigments

Of the three commonly used red pigments(quinacridone red, mercury-cadmium red, and litho-pone red), the 1% quinacridone red formulation isfound to be considerably better than either of theother two in 0.95 density stabilized polyethyleneresins after 1000 hours of exposure in a weathero-meter. There appears to be less difference betweenthe lithopone red and the mercury-cadmium redpigments than between these pigments and thequinacridone red pigment.[115]

The same relationship persists at a 2% pigmentlevel. The 2% quinacridone red is still marginallybetter than the 2% mercury-cadmium red, and bothare considerably better than 2% lithopone red after10,000 hours of exposure. This indicates that as the

pigment concentration increases from 1% to 2%,mercury-cadmium red shows most improvement.Furthermore, the 1% quinacridone red pigment pro-vides better stability than 2% lithopone red.[115]

Previous studies have indicated that chemicallypure (CP) cadmium red would offer virtually thesame protection against UV degradation as mercury-cadmium red. Although the quinacridone red andcadmium red pigments extend the outdoor weather-ability of HDPE, they have limited use due to lack ofcolor stability. The tint strength of both quinacridoneand CP cadmium pigments will weaken when accel-erated by a high humidity atmosphere.The most lightstable red pigment is a combination of CP cadmiumred and mercury-cadmium red pigments.[115]

Earlier studies indicate that iron oxide is excel-lent for use in outdoor applications of HDPE. Anunstabilized system of 0.5% iron oxide was virtuallyunchanged after 2000 hours in the weatherometer,while the tensile strength of 0.5% CP cadmiumred started to decay considerably. Since both theseformulations were unstabilized, this further demon-strates the significant screening effect of iron oxidein polyethylene. From past experience, iron oxidecan be considered to be second only to carbonblack in its ability to stabilize HDPE against UVdegradation.[115]

Orange Pigments

Four pigments at levels of 1% and 2% (coatedmolybdate, lithopone, CP cadmium, and mercury-cadmium) in 0.95 density stabilized polyethylenewere exposed for 10,000 hours in a weathero-meter.At a concentration of 1%, CPcadmium orangeappears to be 10–20% better than other pigments.Less difference can be seen among the pigmentsat the 2% level, although cadmium orange is stillapproximately 10% better than the others. It doesappear that the coated molybdate pigment is some-what better at 1% than at 2%, but this slight decreasefalls within the experimental error range and canbe considered negligible. The only pigment to showa significant difference between the two concentra-tions is lithopone orange. Since this pigment containsless cadmium than CP cadmium, the overall effect isquite the same as a reduced level of cadmium.[115]

The effect of antioxidants on UV stabilization of0.95 density stabilized polyethylene indicates that

39: High Density Polyethylene 197

the antioxidant system plays a major role in theoutdoor performance of pigmented HDPE formu-lations. Two different types of antioxidants werecompounded with a UV stabilizer and 1% and 2%cadmium orange. Antioxidant B imparted muchmore resistance to UV formulations with the properantioxidants for outdoor applications.[115]

Blue and Green Pigments

Phthalocyanine blue, cobalt blue, and ultra-marine blue at a level of 1% were incorporated inan unstabilized polyethylene system and exposed for2000 hours in a weatherometer. This test indicatedthat the phthalocyanine blue pigment provided two tothree times as much UV protection as the ultramarineblue pigment. This level of protection in an unstabi-lized system is quite good. Cobalt blue, however,appears only moderately effective when comparedto phthalocyanine blue.[115]

It is also apparent that ultramarine blue impartslittle or no protection to the polymer, since the perfor-mance of the compound containing ultramarine bluewas a little better than natural HDPE. The same gen-eral trend is found in stabilized as well as unstabilizedsystems.[115]

Many green formulations are prepared by com-bining ultramarine blue and cadmium yellow. Sincethe UV protection provided by ultramarine blue ispoor, and only fair with cadmium yellow, it is notsurprising that the combination is rather ineffective.Phthalocyanine green, however, imparts excellentUV resistance to polyethylene, as do some of thechrome greens. Compounds containing these pig-ments last longer than 6000 hours of weatherometerexposure with no loss of tensile strength.[115]

Pigment Dispersion

Pigment dispersion is important in the com-pounding of any colored resin, since inadequate

dispersion can result in poor appearance, increasedcost, and poor outdoor weatherability. To illustratethe effect of dispersion on weathering, three blendscontaining 0.5% CP cadmium red were prepared.Each of the blends was compared in order to achievea good, fair, and poor pigment dispersion.[115]

Tensile specimens from these compounds wereaged in the weatherometer for 2000 hours. Thetensile strength measured at 2 in./min (5 cm/min)showed very little difference between good/fairpigment dispersion. However, measurements at20 in./min (50 cm/min) revealed that as pigment dis-persion improved, there was a marked increase intensile strength retention after UV exposure. As inthe former case, the specimen with poor pigment dis-persion was much less resistant to degradation thanthe good or even fair pigment system. These dataclearly indicate that pigment dispersion is importantto the UV resistance of a compound.[115]

The degree of carbon black dispersion is also adetermining factor in the effectiveness of a pigmentfor UV protection. Low levels of carbon black, pro-perly dispersed, offer excellent UV protection. Theusual condition is poor dispersion, normally com-pensated by using up to 2.5% black to give ultimateprotection.[115]

Part Thickness

The effect of part thickness plays a significantrole in outdoor life. Since degradation of a part occursfrom the exterior to the interior, the thicker the part,the greater the time required to penetrate to a depththat affects integrity. In one test, a 120 mil (3 mm)thick sample was found to have several times thelife expectancy of a 30 mil (0.75 mm) sample of ayellow HDPE tested outdoors in Arizona.[115]

198 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 39-1. Tensile Strength after EMMA AcceleratedWeathering of Chevron Phillips Marlex® HDPE withChannel Black and Furnace Black

39: High Density Polyethylene 199

Table 39-2. Tensile Strength after AcceleratedWeathering of Chevron Phillips Marlex® HDPE withVariousDegrees of Pigment Dispersion

200 The Effects of UV Light and Weather on Plastics and Elastomers

Table 39-3. Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex® HDPE with UVAbsorber and Various Orange Pigment Systems

39: High Density Polyethylene 201

Table 39-4. Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex® HDPE with 2%Cadmium Yellow Pigment

202 The Effects of UV Light and Weather on Plastics and Elastomers

Table 39-5. Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex® HDPE with UVAbsorber and Various Yellow Pigments

39: High Density Polyethylene 203

Table 39-6. Tensile Strength after Accelerated Weathering of Chevron Phillips Marlex® HDPE with2% TiO2

204 The Effects of UV Light and Weather on Plastics and Elastomers

Table 39-7. Surface and Appearance after Accelerated Weathering of Chevron Phillips Marlex® HDPEwith UV Absorber, Various Antioxidants and Green Pigment

39: High Density Polyethylene 205

Graph 39-1. Tensile Strength after Arizona Outdoor Weathering of Yellow Chevron Phillips Marlex® HDPE.

Graph 39-2. Tensile Strength after Weatherometer Exposure of Yellow Chevron Phillips Marlex® HDPE.

206 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 39-3. Tensile Strength after Weatherometer Exposure of Red Chevron Phillips Marlex® HDPE.

Graph 39-4. Tensile Strength after Weatherometer Exposure of Unstabilized Red Chevron Phillips Marlex®

HDPE.

39: High Density Polyethylene 207

Graph 39-5. Tensile Strength after Weatherometer Exposure of Orange Chevron Phillips Marlex® HDPE.

Graph 39-6. Tensile Strength after Weatherometer Exposure of Blue Chevron Phillips Marlex® HDPE.

208 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 39-7. Tensile Strength after Weatherometer Exposure of Chevron Phillips Marlex® HDPE with 2% ZincOxide and 2% TiO2.

Graph 39-8. Tensile Strength after Weatherometer Exposure of Chevron Phillips Marlex® HDPE with VaryingConcentrations of TiO2.

39: High Density Polyethylene 209

Graph 39-9. Tensile Strength after Weatherometer Exposure of Chevron Phillips Marlex® HDPE with 1% TiO2and UV Stabilizers.

Graph 39-10. Tensile Strength after Weatherometer Exposure of Chevron Phillips Marlex® HDPE with VariousDegrees of Pigment Dispersion.

Chapter 40

Ultrahigh Molecular Weight Polyethylene

Category: Polyolefin, thermoplastic.

General Properties: Molecular degradation may beprevented through the addition of suitable light sta-bilizers. The light-stabilized Ticona GUR® ultrahighmolecular weight polyethylene samples showed nodegradation even after a four-week exposure period;in other words, their physical characteristics werepreserved. The property values were determined for

test specimens 1.3-, 10-, and 20-mm thick after expo-sure to a xenon-lamp device.[117]

The addition of light-absorbing substances pro-vides UV light resistance (e.g., 2.5% carbon blackbeing the most commonly used additive). When thefinished product cannot be black, satisfactory UVresistance (a minimum of five years) can be obtainedwith 0.5 wt% stabilizer.[118]

Chapter 41

Polyethylene Copolymers

General Properties: Polyethylene copolymers suchas ethylene-vinyl acetate copolymer, polyethylene-acrylic acid copolymer, and polyethylene-ionomercopolymer are polyolefins that are comparable toelastomeric materials in softness and flexibility.[111]

Weathering Properties

These materials are resistant to radiation in thevisible spectrum. If polyethylene and its copoly-mers are exposed for long periods outdoors, they aredegraded by radiation at the UV end of the solarspectrum and by atmospheric oxygen. They are alsodegraded by other light sources with a high propor-tion of UV radiation. The degradation mechanismof oxidation combines with high temperatures andleads to a deterioration in the mechanical propertiesand, ultimately, to the destruction of the material.[119]

If moldings are intended for outdoor use, theymust be adequately protected from UV radiation. Byfar the best UV stability is achieved by adding spe-cial grades of carbon black. Proportions of 2–3%improve UV stability by a factor of ten to fifteen.White and chromatic pigments may also improve theUV stability of polyethylene but can also adverselyaffect it.[119]

If moldings in the natural color or in other hueshave to display excellent outdoor performance andfastness to light, the copolymers can be supplied onrequest with special light stabilizers. Good resultsare obtained with hindered amine light stabilizers,in some cases in combination with benzotriazolecompounds. They can increase the resistance toweathering by a factor of about two to four, the extentdepending upon the conditions.[119]

214 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 41-1. Elongation Retained after Xenon Arc Weatherometer Exposure of Ethylene-Vinyl AcetatePolyethylene Copolymer Greenhouse Film

Chapter 42

Polypropylene

Category: Polyolefin, thermoplastic.

General Properties: Without added UV stabilizers,polypropylene has poor UV resistance.

Weathering Properties:Stabilization

Polypropylene homopolymers and copolymersfor automotive applications have traditionally beenstabilized with a combination of hindered phenolic/hindered phosphite process stabilizers and hin-dered amine light stabilizers (HALSs). In organicpigmented applications, the addition of a benzo-triazole UV absorber enhances light stability andhelps prevent the pigment from fading.[121]

Car manufacturers strive to produce auto-mobiles that will look and perform well for ten years.For aesthetic and styling reasons, manufacturersoften partially paint molded-in color polypropy-lene. Thus light stabilizers must provide long-termstability and must not interfere with the adhesionof coatings to the substrate. Noninteracting NORHALSs help polypropylene producers achieve both

outstanding long-term light stability and good adhe-sion to thermoplastic polyolefin surfaces.[121]

Polypropylene geomembrane systems used inexposed (i.e., nonburied) applications are susceptibleto cracks and other UV-induced damage.

Stevens Geomembranes/JPS Elastomerics hasconducted extensive UV resistance testing onpolypropylene geomembrane sheets. Xenon arcweatherometer (ASTM G-26) exposure of the sheetstested exceeded 10,000 hours at 80◦C (176◦F) withno indication of visual surface deterioration. Theresults from extensive outdoor exposure testing inFlorida and Arizona using EMMAQUA acceler-ated aging techniques (ASTM G-90) showed thatthe polypropylene geomembranes tested passed the4 million langley (167,360 MJ/m2 total radia-tion) mark with no evidence of visual surfacedeterioration.[122]

Table 42-1 correlates langleys to years of outdoorperformance. “A” is the average langleys receivedper day, based on a five-year average (1966–1970)of global solar radiation on the earth’s surface,as received on a horizontal surface; data obtainedfrom measurements reported by the US WeatherBureau. “B” is the number of years required to obtain4 million langleys at the location indicated.[122]

216 The Effects of UV Light and Weather on Plastics and Elastomers

Table 42-1. Conversions of EMMAQUA to Real-Time Performance by Geographic Location[122]

Location A B

Albuquerque, NM 484 22

Argonne National Laboratory 327 34

Atlanta, GA 375 30

Cape Hatteras, NC 394 28

Fairbanks, AK 250 44

Grand Junction, CO 457 24

Los Angeles, CA 444 24

Miami, FL 451 24

New York, NY 323 34

Oak Ridge, TN 356 30

San Antonio, TX 411 26

Seattle/Tacoma, WA 307 36

42: Polypropylene 217

Weathering Properties by Material Supplier Trade Name

Table 42-2. Tensile Strength after Florida and Puerto Rico Outdoor Weathering of PolypropyleneContaining Various Antioxidant Stabilizers

218 The Effects of UV Light and Weather on Plastics and Elastomers

Table 42-3. Mechanical Properties Retained after California and Pennsylvania Outdoor Weathering ofGlass-Reinforced Polypropylene

42: Polypropylene 219

Table 42-4. Tensile Strength Retained after Puerto Rico Outdoor Weathering for Polypropylene Contain-ing Antioxidants and UV Stabilizers

220 The Effects of UV Light and Weather on Plastics and Elastomers

Table 42-5. Color and Gloss Changes after QUV Accelerated Weathering for Polypropylene ContainingMicrocal Calcium Carbonate and Pure Calcium Carbonate

Graph 42-1. Kilolangleys to 50% Retained Tensile Strength and Days to Embrittlement after 45◦ South Floridaand Oven Aging at 120◦C of UV-Stabilized Polypropylene Plaques.[121]

0.2% Tinuvin 770

0.2% Tinuvin 791

0.2% Chimassorb 944

600 400 200 0 200 400 600

kLys Days

Note: Sample: 2 mm (80 mil) polypropylene plaques. Base stabilization: 0.15% Irganox B215 + 0.1% calcium stearate.Exposure: Florida 45◦ south and oven aging at 120◦C. Test criteria: kilolangleys to 50% retained tensile strength + days toembrittlement.

42: Polypropylene 221

Graph 42-2. Surface Roughness after 45◦ South Florida Weathering Exposure of UV-Stabilized PolypropylenePlaques.[121]

1.2

1.0

0.8

0.6

0.4

0.2

00 100 200 300 400 500

Sur

face

Rou

ghne

ss

kLys

Control

0.4% Tinuvin 770 +0.2% Tinuvin 328

0.4% Tinuvin 791 +0.2% Tinuvin 328

Note: Sample: 2 mm (80 mil) polypropylene copolymer plaques. Base stabilization: 0.1% Irganox B225 + calcium stearate.Exposure: Florida 45◦ south. Test criterion: increase in kilolangleys to surface roughness.

Graph 42-3. Color Change, �E, after Accelerated Weathering for UV-Stabilized Polypropylene AutomotiveFibers.[124]

0.8% Chimassorb 944

0.8% Chimassorb 2020

12

10

8

6

4

2

00 113 301

kJ602 902 1203

∆E

Note: Samples contain 152/37 dtex, blue pigment. Base stabilization: Fiberstab® L112 + calcium stearate. Exposure: SAEJ1885, WOM Ci65, 0.55 W/m2 at 340 nm, bpt 89◦C.

Chapter 43

Polymethylpentene

Category: Polyolefin, thermoplastic.

General Properties: Mitsui Chemicals TPX™, a4-methylpentene-1-based polyolefin, possesses manycharacteristics inherent in traditional polyolefins.

Weathering Properties by Material Supplier Trade Name

Graph 43-1. Izod Impact Strength Retained after Weatherometer Exposure for Mitsui TPX™ RT18 Polymethyl-pentene.

Weathering Properties

The weatherability of TPX™ is comparable withthat of polypropylene.AlthoughTPX™ is susceptibleto UV deterioration, this can be virtually eliminatedby adding UV stabilizers (MSW 303).[125]

Chapter 44

Polyphenylene Sulfide

Category: Thermoplastic.

General Properties: Chevron Phillips Ryton®

R-4-200NA is an advanced 40% fiberglass rein-forced polyphenylene sulfide compound.

Weathering Properties by Material Supplier Trade Name

Table 44-1. Material Properties Retained and Surface Erosion after Atlas Weatherometer AcceleratedWeathering of Chevron Phillips Ryton® R4 Polyphenylene Sulfide

Chapter 45

General Purpose Polystyrene

Category: Styrenic, thermoplastic.

General Properties: General purpose polystyreneis available in various grades such as easy flow,intermediate flow, and high heat resins.

Weathering Properties

Polystyrene undergoes light-induced yellowingupon exposure to UV light. Although the origin ofthe yellowing is not clear, the presence of air slowsdown the yellowing process. Yellowing is attributedto conjugated polyenes, various oxygenated species,or products of ring-opening reactions.[5]

BASF Polystyrol® is stabilized against agingcaused by exposure to atmospheric oxygen at ele-vated temperatures. Under normal light and temper-ature conditions indoors, parts made of Polystyrol®

retain their appearance and functionality for years.The UV rays in direct sunlight are primarily respon-sible for damage outdoors. This aging shows up bothas a gradual change in appearance (i.e., yellowingand loss of surface gloss) and as a decrease in themechanical strength. Dark-colored products havebetter resistance than pale or transparent products.

Weathering Properties by Material Supplier Trade Name

Table 45-1. Photo-Oxidation of Polystyrene[3]

Oxygen UV Radiation Oxygen inPressure (mm) Time (hrs) Product (%) Color

0 0 0.11 Nearly colorless

0 250 0.13 Light yellow

20 0 0.10 Nearly colorless

20 250 0.14 Yellow–orange

Note: The total exposure time is 250 hrs at 115–120◦C in all cases.

For the above reasons, polystyrene is not recom-mended for articles that are used outdoors fora prolonged period. The yellowing resistance ofpolystyrene can be significantly improved by theaddition of UV stabilizers.[128]

Under the normal conditions of light and tem-perature encountered indoors, Polystyrol® moldingsretain their appearance and perform their functionsefficiently for many years.[129]

Polystyrene foams generally have poor outdoorweathering resistance and are not recommended forlong-term outdoor use. The plastic matrix deterio-rates when exposed to direct sunlight for extendedperiods, as evidenced by a characteristic yellowing,loss of surface gloss, and by a decrease in mechani-cal strength. Darker formulations perform betterthan pale or transparent types.[130]

To protect polystyrene foam against the effectof outdoor weathering and physical damage, an ade-quate coating should be applied on the surface.[130]

Materials subjected to oxygen are degradedmuch faster in the presence of radiation than inits absence and vice versa. The discoloration ofpolystyrene occurs more rapidly when irradiationtakes place in air or oxygen.[3]

228 The Effects of UV Light and Weather on Plastics and Elastomers

Table 45-2. Mechanical Properties Retained after California and Pennsylvania Outdoor Weathering ofGlass-Reinforced General Purpose Polystyrene

45: General Purpose Polystyrene 229

Graph 45-1. Yellowness Index after Atlas Fadeometer Exposure of General Purpose Polystyrene.

Graph 45-2. Yellowness Index after Fluorescent Lamp Exposure of BASF Polystyrol® General PurposePolystyrene.

Chapter 46

High Impact Polystyrene

Category: Styrenic, thermoplastic.

General Properties: High impact polystyrene(HIPS) is modified with polybutadiene elastomers.The high impact grades contain 6–12% of the elas-tomer. The elastomers are introduced into the basepolymer to improve the impact resistance and defor-mation before fracture. Through the incorporation ofdifferent elastomers into the chain, products with awide range of properties can be produced.

NOVA Chemicals Styrosun® resins are weather-able HIPS specifically designed for use in out-door applications. Styrosun® contains an inherentlyweather resistant rubber that is cross-linked andgrafted into the polymer matrix. This unique poly-mer structure provides long-term color stability andphysical property retention.[132]

Weathering Properties

Unmodified HIPS resins usually experiencegreater change from outdoor exposure than gen-eral purpose polystyrene formulations. HIPS resinsusually show less change than resins modifiedwith ignition-resistant chemical additives.[133] Solarradiation, particularly at the UV end of the spectrum,acts together with atmospheric oxygen to causeembrittlement and yellowing. These changes occurmainly in the butadiene elastomer.[13]

Styrosun® resins are resistant to sunlight andmaintain significant physical properties after weath-ering. The weather resistant properties of Styrosun®

resins are achieved by combining proprietary UVstabilization technology with an inherently UV-stable impact modifier.[134]

The key advantage of Styrosun® resin is theretention of physical properties after outdoor weath-ering. Applications using Styrosun® resins main-tain functional product life and toughness after UVexposure.[134]

Molded plaques of Styrosun® and typical com-petitive outdoor polymers were exposed at fourdifferent locations in the United States and colorretention (as �E) was monitored over time. Thecolor retention performance of Styrosun® HIPS,acrylonitrile-styrene-acrylate (ASA), UV-stabilizedacrylonitrile-butadiene-styrene (UV-ABS), UV-stabilized high impact polystyrene (UV-HIPS), andfilled polypropylene (PP) was compared after 18months at four different exposure sites in the UnitedStates. The results demonstrated that Styrosun® andASA had equivalent performance (�E range 4.9–6.5). UV-ABS and UV-HIPS were also equivalent inperformance (�E range 18.5–26.1). Filled PP exhib-ited the smallest change in color over this exposureperiod (�E range 1.6–2.2).A�E value of 5 or less isgenerally considered to be negligible unless directlycompared to an unexposed control.[132]

Molded plaques of Styrosun® and various othermaterials were exposed in Xenon Arc Weather-Ometers® (ATLAS Material Testing TechnologyLLC) as per ASTM protocol G155 Cycle 2. By cal-culation, 3000 hours of accelerated weathering bythis protocol is theoretically equivalent to one yearof exposure in Florida or 0.8 years in Arizona. Thecolor retention of white Styrosun® after 3000 hoursof accelerated weathering was identical to its colorretention after 18 months of Florida outdoor weather-ing. In this accelerated exposure test, neitherASAnorUV-ABS exhibited the same degree of color changeseen after Florida exposure. However UV-ABS wasagain less resistant to color change than Styrosun®.Filled PP exhibited the smallest change in color overthis exposure period. Examination of the acceleratedweathering �E graph also illustrates the significantamount of scatter in the data.[132]

The samples were also tested for retained impactstrengths. There are three impact results reportedby a Dynatup® (Instron Corporation) impact testinstrument. The “energy at maximum load” is theenergy at the moment of impact, the “total energy”

232 The Effects of UV Light and Weather on Plastics and Elastomers

is the energy required to break the test plaque, andthe “maximum load” is the weight required to breakthe test plaque. When these absolute numbers werecompared, in all cases Styrosun® was stronger andtougher than filled PP, but not as strong as UV-ABS.When the percentage retention values were com-pared, Styrosun® was found to retain its propertiessignificantly better than UV-ABS and similar tofilled PP.[132]

Weathering Properties by Material Supplier Trade Name

Table 46-1. Color Change, �E, after 18 Months of Florida Outdoor Exposure for NOVA ChemicalsStyrosun® HIPS and Other Materials

Material Family High Impact Polystyrene

Material Grade NOVA Chemicals Styrosun® HIPS and Other Materials

Reference Number 132

Exposure Conditions Florida, Arizona, Kentucky, Illinois

Exposure Time 18 months

Materials Styrosun® 3600 ASA UV-ABS UV-HIPS Filled PP

SURFACE AND APPEARANCE

�E Florida 5.2 5.4 18.5 19.4 2.2

�E Arizona 6.5 6.5 25.3 23.7 1.8

�E Kentucky 5.0 4.9 24.2 22.0 1.6

�E Illinois 5.8 4.8 26.1 23.1 1.6

Table 46-2. Color Change, �E, after 18 Months of Florida Outdoor Exposure and 3000 hours ofAccelerated Weathering for NOVA Chemicals Styrosun® HIPS and Other Materials

Material Family High Impact Polystyrene

Material Grade NOVA Chemicals Styrosun® HIPS and Other Materials

Reference Number 132

Exposure Conditions Florida Outdoor Exposure Accelerated Exposure

Exposure Time 18 months 3000 hrs

Materials Styrosun® 3600 ASA UV-ABS Filled PP Styrosun® 3600 ASA UV-ABS Filled PP

SURFACE AND APPEARANCE

�E 5.2 5.4 18.5 2.2 5.2 1.3 7.5 2.1

Addition of UV stabilizers overcomes the yel-lowing and brittleness associated with prolongedexposure of unmodified HIPS to sunlight.[132] Com-binations of UV absorbors (UVAs) and hinderedamine light stabilizers (HALSs) can provideimproved performance.[135]

46: High Impact Polystyrene 233

Table 46-3. Impact Retention after 3000 hours of Accelerated Weathering for NOVA ChemicalsStyrosun® HIPS and Other Materials

Material Family High Impact Polystyrene

Material Grade NOVA Chemicals Styrosun® HIPS and Other Materials

Reference Number 132

Exposure Conditions Accelerated Exposure

Exposure Time 3000 hrs

Materials Styrosun® 3600 Styrosun® 3600 UV-ABS Filled PP

RETENTION OF ENERGY AT MAXIMUM LOAD

Impact Retention (%) 80.7 102.7 39.1 107.2

RETENTION OF TOTAL ENERGY

Impact Retention (%) 88.3 76.9 42.9 135.1

RETENTION OF MAXIMUM LOAD

Impact Retention (%) 88.4 82.6 28.2 98.1

Graph 46-1. Yellowness Index after Fadeometer Exposure of Dow Styron® Impact and Flame-RetardantPolystyrene and Dow Styron® Unmodified Polystyrene.

234 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 46-2. Color Change, �E, after Florida Outdoor Exposure of NOVA Chemicals Styrosun® HIPS andOther Materials.[132]

White Styrosun3600

White ASA

FLORIDA∆E

White UV ABS0

5

10

15

20

25

White UV HIPS White filled PP

3 months 6 months 9 months 12 months 15 months 18 months

Graph 46-3. Color Change, �E, after Arizona Outdoor Exposure of NOVA Chemicals Styrosun® HIPS andOther Materials.[132]

0

5

10

15

20

25

30

White Styrosun3600

White ASA White UV ABS White UV HIPS White filled PP

ARIZONA

∆E

3 months 6 months 9 months 12 months 15 months 18 months

46: High Impact Polystyrene 235

Graph 46-4. Color Change, �E, after Kentucky Outdoor Exposure of NOVA Chemicals Styrosun® HIPS andOther Materials.[132]

0

5

10

15

20

25

30

White Styrosun3600

White ASA White UV ABS White UV HIPS White filled PP

KENTUCKY

∆E

3 months 6 months 9 months 12 months 15 months 18 months

Graph 46-5. Color Change, �E, after Illinois Outdoor Exposure of NOVA Chemicals Styrosun® HIPS and OtherMaterials.[132]

White Styrosun3600

White ASA

ILLINOIS

∆E

White UV ABS

0

5

10

15

20

25

30

White UV HIPS White filled PP

3 months 6 months 9 months 12 months 15 months 18 months

236 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 46-6. Impact Property Retention, Energy at Maximum Load, after 3000 hours of Atlas Weather-Ometers® Exposure for NOVA Chemicals Styrosun® HIPS and Other Materials.[132]

140.0

120.0

100.0

80.0

60.0

40.0

20.0

0.00 500 1000 1500 2000 2500 3000

Ene

rgy

at M

axim

um L

oad

(% R

eten

tion)

Exposure Time (hrs)

UV ABS-BLACK SSUN 3600 BLACK SSUN 6600 BLACK FILLED PP-WHITE

Graph 46-7. Impact Property Retention, Total Energy, after 3000 hours of Atlas Weather-Ometers® Exposurefor NOVA Chemicals Styrosun® HIPS and Other Materials.[132]

UV ABS-BLACK SSUN 3600 BLACK SSUN 6600 BLACK FILLED PP-WHITE

200.0

180.0

160.0

140.0

120.0

100.0

80.0

60.0

40.0

20.0

0.00 500 1000 1500 2000 2500 3000

Tota

l Ene

rgy

(% R

eten

tion)

Exposure Time (hrs)

46: High Impact Polystyrene 237

Graph 46-8. Impact Property Retention, Maximum Load, after 3000 hours of Atlas Weather-Ometers®

Exposure for NOVA Chemicals Styrosun® HIPS and Other Materials.[132]

UV ABS-BLACK SSUN 3600 BLACK SSUN 6600 BLACK FILLED PP-WHITE

0 500 1000 1500 2000 2500 3000

Exposure Time (hrs)

120.0

100.0

80.0

60.0

40.0

20.0

0.0

Max

imum

Loa

d (%

Ret

entio

n)

Graph 46-9. Impact Strength after Xenon Arc Weathering of HIPS as per ISO 4692-2.[135]

80

60

40

20

00 250 500 750 1000

Control

0.25% UVA0.25% HALS

Exposure Time (hrs)

Impa

ct S

tren

gth

(kJ/

m2 )

Note: 2 mm plaques;base stabilization:0.05% Irganox® 245;UVA:Tinuvin® P,Tinuvin® 327, orTinuvin® 328;HALS:Tinuvin®

770, Tinuvin® 765, or Chimassorb® 119.

238 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 46-10. Yellowness Index after Xenon Arc Weathering of HIPS as per ISO 4892-2.[136]

20

15

10

5

00 1000 2000 3000 4000 5000

Control

0.1% Tinuvin P0.1% Tinuvin 770

Yello

wne

ss In

dex

Exposure Time (hrs)

Chapter 47

Polysulfone

Category: Thermoplastic.

General Properties: Solvay Plastics Udel® poly-sulfone is an amorphous high performance polymer.

Weathering Properties

Because of the aromatic ether backbone, poly-sulfone is susceptible to chemical degradation

Weathering Properties by Material Supplier Trade Name

Table 47-1. Mechanical Properties Retained after Outdoor Weathering of Glass-Reinforced Polysulfonein California and Pennsylvania

upon outdoor exposure. Weather resistance can beimproved by the addition of carbon black. Protec-tive paints or coatings can be used to preserve theproperties of polysulfone articles exposed to directsunlight.[137]

240 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 47-1. Tensile Strength after Xenon Arc Weatherometer Exposure of Polysulfone.

Chapter 48

Polyethersulfone

Category: Engineering thermoplastic.

General Properties: Polyethersulfone (PES) is aheat-resistant, transparent, amber, noncrystallineengineering plastic.[138]

Weathering Properties

The weathering resistance of natural PES resinis not very good and therefore it is not suitable foroutdoor use.[138]

Weathering Properties by Material Supplier Trade Name

Graph 48-1. Tensile Strength after Xenon Arc Weatherometer Exposure of PES.

BASF Ultrason® moldings yellow and embrittlequickly when exposed outdoors. The moldings canbe protected from degradation by the incorporationof carbon black, surface coating, or metallizing.[45]

Chapter 49

Styrene-Acrylonitrile Copolymer

Category: Thermoplastic.

General Properties: The properties of BASFLuran® styrene-acrylonitrile (SAN) copolymer areprimarily determined by the acrylonitrile contentand the molecular weight or molecular weightdistribution.

Weathering Properties

The mechanical properties of Luran® specimensdeteriorate after one or two years of outdoor exposure

(at an angle of 45◦ facing south in Ludwigshafen,Germany). The extent to which the mechanical pro-perties are impaired depends on the nature of the spe-cimen and the test procedure. Other consequences ofoutdoor exposure are yellowing and a rough surface.Luran® resins are also available in a UV-stabilizedform. It can be seen that the rate of decrease inflexural strength is much less for Luran® resins con-taining UV stabilizers. Another advantage of UVstabilization is that the color retention is considerablyimproved.[139]

244 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 49-1. Surface and Appearance Properties after Arizona Outdoor Weathering of Dow Tyril® SANCopolymer

Graph 49-1. Yellowness Index after Arizona Outdoor Weathering of Dow Tyril® SAN Copolymer.

49: Styrene-Acrylonitrile Copolymer 245

Graph 49-2. Yellowness Index after UV-CON Accelerated Weathering Exposure of SAN Copolymer.

Chapter 50

Styrene-Butadiene Copolymer

Category: Styrene-butadiene, thermoplastic.

General Properties: Chevron Phillips K-Resin® isa transparent styrene-butadiene copolymer that canbe impact modified as well as UV stabilized.

Weathering Properties

K-Resin® copolymers are styrenic copolymersthat will yellow and ultimately craze and embrittlewith long-term exposure to direct sunlight. Pre-vious weatherometer testing shows that K-Resin®

is susceptible to yellowing and physical propertydeterioration induced by UV light. With the addi-tion of appropriate UV stabilizers, the estimated lifeof a K-Resin® part may be extended. In general,K-Resin® will withstand UV exposure for approx-imately three months before excessive brittlenessand yellowing are evident. Modifying K-Resin® withcommercially available UV stabilizers will extendthe outdoor life of the material for up to eigh-teen months depending on the stabilizer packageused.[142]

Indoor UV Light Resistance andIndirect Sunlight[142]

K-Resin® polymers are used in many displayapplications that are often subjected to reduced levelsof UV light, by indirect sunlight or fluorescentlighting.

A study was conducted to determine the extentof K-Resin® yellowing under these conditions. Foursamples evaluated in the test included KR01, KR03,and KR03 with two different UV stabilizers (CibaSpecialty Chemicals Tinuvin® P and Tinuvin® 770).Samples were prepared by adding 0.5% of each UVstabilizer to a K-Resin® sample by dryblending thesample prior to extrusion and palletizing. Tinuvin®

P is a UV absorber and Tinuvin® 770 is a hinderedamine light stabilizer. The clarity of these blends was

very good, but some slight yellow color developedwhen the UV stabilizers were initially added.

The samples were compression molded into15.24 mm plaques. One set was placed in a UV-CON® tester, approximately 4′′ (10 cm) from a bankof four fluorescent lights. Another set was placed ona window ledge exposed to indirect sunlight. A thirdset was placed in a dark container so that the speci-mens were not exposed to any light source. Hunter“b” color was measured initially and at intervals of3, 6, 12, 18, and 24 months.

As expected, the non-UV stabilized KR01 andKR03 responded similarly in all circumstances.The UV-stabilized polymers demonstrated improvedresistance to yellowing when exposed to UV lightsources. When no light source was present, none ofthe K-Resin® samples yellowed appreciably over thetwo-year period.

In the UV-CON® test, the most severe test,the addition of a UV additive improved the perfor-mance substantially. KR01 and KR03 unmodifiedsamples discolored significantly between six andtwelve months, and continued to further discolorwith extended exposure. Tinuvin® P modified KR03outperformed Tinuvin® 770 modified KR03, aftertwo years, having about half as much yellow colordevelopment.

In indirect sunlight, the modified KR01 andKR03 samples discolored most significantly aftertwelve months. The KR03 sample containing 0.5%Tinuvin® P performed better, with only minimalyellowing over the two-year test period. Tinuvin®

770 modified KR03 did not perform as well asTinuvin® Pmodified KR03, discoloring significantlyafter twelve months.

K-Resin® polymers, which will yellow whensubjected to long-term exposure to direct sunlight,can also yellow with less severe UV exposure.Yellowing can be significantly reduced by the addi-tion of UV stabilizers. Tinuvin® P is more effectivethan Tinuvin® 770 for fluorescent and indirect lightexposure. K-Resin® parts stored in the dark showedno significant yellowing over at least a two-yearperiod.

Chapter 51

Polyvinyl Chloride

Category: Vinyl, thermoplastic.

General Properties: PolyOne Geon® exterior com-pounds are UV stable and can withstand extremeweather conditions with good color and impactretention over time.

Weathering Properties

Of the synthetic polymers, polyvinyl chloride(PVC) is best known for its tendency to undergophotoyellowing. Yellowing is often the result ofphotothermal mechanisms that lead to the forma-tion of conjugated polyenes. The rate of yellow-ing in the white profiles widely used in siding,window frames, and pipes can be slowed throughthe use of an opacifier, generally rutile titania. Thereaction is localized in the surface layers of thepolymer especially in opaque formulations used inbuilding applications. The wavelengths that causeyellowing of PVC (the visible radiation >400 nm)also tend to cause photobleaching. Several possiblephotobleaching mechanisms are reported in theliterature but the process is little understood.[11]

The ability of plasticized PVC to withstand out-door exposure is influenced by many factors. Theseinclude the flexibility and the thickness of the fab-ricated product as well as the additives that areincorporated into the formulation.[11]

Testing has yielded the following recommenda-tions: plasticizer concentration in the range of 35parts per hundred parts of PVC, use of a good phos-phate ester as 10% of the plasticizer system, useof some pigmentation, and incorporation of treatedrutile titanium dioxide. UV light absorbers must beincluded in clear films. In addition to the epoxyand barium-cadmium-containing stabilizers, includea phosphate ester in the stabilizer system. The thickerthe film, the longer will be its expected outdoorlife.[11]

Thickness

Degradation as a result of environmental expo-sure begins on the surface where radiation intensityis the greatest. The thicker sections provide a largerreservoir of stabilizers. The stabilizer readily, andconstantly, migrates from the bulk to the film’s sur-face. Thus thicker films and sheets contain more ofthe preventative stabilizer, resulting in longer life.

Plasticizers[11]

All plasticizers, and all plasticizer concentra-tions, do not perform in the same manner. Generally,more volatile plasticizers will yield films with ashorter outdoor life expectancy. Clear films, includ-ing a UV absorber (UVA), plasticized at 50 phr (partsper hundred resin) were exposed in 4 mil (100 µm),10 mil (250 µm), and 20 mil (500 µm) thicknesses inFlorida. In this evaluation, four general-purpose plas-ticizers were studied: two were highly branched—diisodecyl phthalate (DIDP) and diisononyl phtha-late (DINP), one was singly branched—dioctylphthalate (DOP), and the fourth plasticizer—heptyl-nonyl-undecyl phthalate—was essentially linear.This study revealed the benefit of using the less-branched phthalate plasticizers for products to beused outdoors.

A prior, limited, outdoor weathering study inFlorida showed 35 phr plasticizer to be the mostbeneficial for long-term durability. This was basedon work using two plasticizer systems withoutUVA. One was DOP and the other plasticizer sys-tem was 90% DOP and 10% 2-ethylhexyl diphenylphosphate.

Also seen in this study was the synergistic influ-ence of the phosphate plasticizer in thin films of 4 mil(100 µm) thickness.At the lower two concentrations,where films are relatively stiff, the increase in servicelife due to the addition of a phosphate plasticizeris 9–15%. Soft and flexible films, those with 50 and

250 The Effects of UV Light and Weather on Plastics and Elastomers

Table 51-1. Exposure Results of Various Plasticized Films with Varying Thicknesses

Plasticizer Film Thickness Exposure Time Result

DIDP 4 mil (100 µm) 24 months Entirely brown

DIDP 10 mil (250 µm) 30 months Entirely brown

DIDP 20 mil (500 µm) 30 months Entirely brown

DINP 4 mil (100 µm) 24 months Entirely brown

DOP 4 mil (100 µm) 36 months No browning

DOP 10 mil (250 µm) 36 months No browning

DOP 20 mil (500 µm) 36 months No browning

Heptyl-nonyl-undecyl

phthalate4 mil (100 µm) 36 months No browning

Heptyl-nonyl-undecyl

phthalate10 mil (250 µm) 36 months No browning

Heptyl-nonyl-undecyl

phthalate20 mil (500 µm) 36 months No browning

Table 51-2. Outdoor Life of DOP-Plasticized 4 mil (100 µm) Thick Films withVaried Plasticizer Levels

Plasticizer Level Outdoor Life*

20 phr 13 months

35 phr 23 months

50 phr 15 months

70 phr 11 months

∗Elongation was the measure for outdoor life.

70 phr of plasticizer, have a dramatic increase in lifeexpectancy. The addition of a small amount of phos-phate plasticizer yields a 50% increase in outdoorserviceability.

Later work from the same laboratory showed theresponse of films containing UVAs and plasticized at50 phr to outdoor aging when the plasticizer systemis varied from all DOP to all 2-ethylhexyl diphenylphosphate. The optimum level of phosphate plas-ticizer was determined to be 10–15% of the totalplasticizer system. The benefit of the phosphate syn-ergism is seen in 20 mil (50 µm) thick films as wellas in the thin 4 mil (100 µm) films.

Additional Plasticizers

General performance monomerics diisodecylglutarate (DIDG) and DOP were tested withpolymerics G-4,000 (glutarate—viscosity, cps) andG-12,000 for yellowness index change after two,four, and six months of direct aging. Both mono-merics show relatively high initial and longer-termtendencies to yellow. G-4,000 and G-12,000 pro-vide excellent short-term and longer-term resistanceto discoloration by yellowing. Glutarate polymericsin general have a proven history of providing goodresistance to weathering for PVC compounds.[143]

51: Polyvinyl Chloride 251

Table 51-3. Direct Weathering of Select Plasticizers in PVC[143]

Yellowness Index Change

Exposure Time DIDG DOP G-4,000 G-12,000

2 months 8.25 4.93 0.17 0.5

4 months 9.25 8.93 3.17 1.5

6 months 14.9 9.85 4.55 5.35

Note: 45◦ south, with backing, South Miami. Recipe: PVC—100, BaCd—1, UV stabilizer—0.5, Plasticizer—67, ESO—3.

Table 51-4. Underglass Weathering of Select Plasticizers in PVC[11]

Yellowness Index Change

Exposure Time DIDG DOP A-20,000 G-12,000

2 months −1.9 2.36 −1.08 −2.83

4 months 2.94 6.05 0.57 −0.28

6 months 8.38 6.05 2.72 0.34

Note: 45◦ south, with backing, South Miami. Recipe: PVC—100, BaCd—1, UV Stabilizer—0.5, Plasticizer—67,ESO—3.

Underglass weathering net changes from initialyellowness values for monomerics DOP and DIDGand polymerics A-20,000 (adipate—viscosity) andG-12,000 were tested. The magnitude of short-termand longer-term yellowness index change values islesser overall for the underglass-weathered com-pounds compared with those which were directlyaged. Polymeric polyesters A-20,000 and G-12,000provide about a threefold reduction in yellownessindex change compared with the general perfor-mance monomerics.[11]

Stabilizers[11]

When formulating flexible PVC films and sheetsfor outdoor use, the influence of the complete sta-bilizer system including epoxidized soybean oil,several metal salts of organic acids, a phosphate ester,and a UVA (2-hydroxy-4-methoxy benzophenone)must be considered.

The influence of stabilizers on the outdoor dura-bility of flexible PVC was measured using epoxy-cadmium stabilizers individually and in synergisticmixtures with 2-hydroxy-4-methoxy benzophenone.

“Epoxy-cadmium” is a synergistic mixture of anepoxy compound, a barium-cadmium salt of anorganic acid, and a phosphate ester. When only theepoxy compound and barium-cadmium salt wereused, decomposition occurred quite early, throughdiscoloration, serious tack formation, and the loss ofelongation.

The addition of a UV light stabilizer, suchas 2-hydroxy-4-methoxy benzophenone, had essen-tially no benefit. However, triphenyl phosphate byitself yielded a longer life than either of the abovestabilizers. When 2-hydroxy-4-methoxy benzo-phenone was added to triphenyl phosphate, there wasa large improvement in the weathering life of thefilm. Although the epoxy and barium-cadmium con-stituents were not necessarily needed to achieve goodoutdoor durability, they are definitely required toensure adequate heat stability during the processingof flexible PVC.

Pigments and Colorants

The outdoor life expectancy of flexiblePVC may be improved through pigmentation.

252 The Effects of UV Light and Weather on Plastics and Elastomers

Table 51-5. Titanium Dioxide in Films of Three Thicknesses Exposed in Florida[11]

Thicknesses TiO2 UVA Time to Failure

4 mil (100 µm) No No 22 months

10 mil (250 µm) No No 22 months

20 mil (500 µm) No No 22 months

4 mil (100 µm) Yes No 32 months

10 mil (250 µm) Yes No 47 months

20 mil (500 µm) Yes No 76 months

Increasing quantities of anatase and rutile titaniumdioxide improved the reflectance characteristics ofplasticized PVC. Accelerated weathering studiesrevealed rutile titanium dioxide to be decidedlysuperior to anatase as a light-stabilizing agent.[11]

It was found that “When an untreated rutileabsorbs UV light, the absorbed energy goes intoa photochemical reaction that liberates active oxy-gen.” For this reason, rutile that is used in plastics isgiven a surface treatment which inhibits this photo-chemical reaction and causes the absorbed UVenergy to be dissipated as heat.[11]

Colored pigments strongly assist in the main-tenance of mechanical properties by protecting theplasticized PVC compositions from degradation.Combinations of pigments are beneficial for long-term outdoor aging because they can shield thevisible and the UV range—thus the use of rutile tita-nium dioxide in combination with a selected coloredpigment was found to provide quite good weatheringresistance.[11]

Similar outdoor studies were carried out withblue and black films. Both colorants, phthalocyanineblue at 0.9 phr and channel black at 1 phr, definitelyextend the weathering life of flexible PVC filmsand sheets. The 20 mil (500 µm) blue film survived80 months, over six and a half years, before failingthe room temperature brittleness test.[11]

The use of black pigments is encouraged toachieve the maximum outdoor life for flexible PVCproducts. The 20 mil (500 µm, 0.5 mm) sheets with-stood five years of Florida exposure before reachingthe 0◦C brittleness temperature. Extrapolating this,a 60 mil (1.5 mm), black pigmented, flexible PVCsheet can withstand more than ten years of outdoorexposure in most environments.[11]

Yellowing

PVC is susceptible to photoyellowing. “Thephotothermal mechanisms leading to the forma-tion of conjugated polyenes that cause yellowingis well understood and documented in the litera-ture. An opacifier (generally rutile titania) is usedto slow down the rate of yellowing in white profileswidely used in siding, window frames, and pipes.The reaction is localized in the surface layers ofthe polymer especially in opaque formulations usedin building applications. The activation energy fordehydrochlorination is reported to have a temper-ature coefficient of 8–18 kJ/mol, suggesting thisprocess is readily enhanced at high temperatures.As with wool and paper, while the UV wave-lengths cause yellowing of PVC, the visible radiation>400 nm tends to cause photobleaching. Severalpossible photobleaching mechanisms are reported inthe literature but the process is little understood.”[5]

Weathering Properties:Stabilization

Ciba® Tinuvin® XT 833 protects PVC fromthe harmful effects of light exposure and helps itmaintain its initial appearance, initial tensile andelongation properties, and physical integrity duringlong-term weathering. In PVC roofing membranes,for example, it minimizes discoloration and embrit-tlement and enables the membranes to retain theirmoisture barrier properties and reflectivity. In somecases, studies show that even in an acidic environ-ment Tinuvin® XT 833 can double the expected

51: Polyvinyl Chloride 253

lifetime of flexible PVC compared to UVAs.As PVCdegrades, it releases hydrochloric acid which ter-minates the effectiveness of hindered amine lightstabilizers (HALSs) as a light stabilizer or at least-severely reduces HALS activity. Thus a unique class

Graph 51-1. Elongation after Xenon Exposure of Various UV Stabilized PVC Formulations.[144]

0 6000

Xenon Exposure (hrs)

8000

900

800

700

600

500

400

300

200

100

0

Elo

ngat

ion

(%)

Tinuvin XT 833

Commercial PVC A

Commercial PVC B

Graph 51-2. Elongation Retention after Xenon Exposure of Various UV-Stabilized PVC Formulations.[144]

80

70

60

50

40

30

20

10

02.0%

UVA #12.0%

UVA #2

Xenon Exposure (6000 hrs)

1.0%Tinuvin XT 833

Elo

ngat

ion

Ret

entio

n (%

)

of light stabilizers known as NOR HALSs (non-basic HALSs) was developed. This completely newmolecule is synthesized to function well in an acidicenvironment.[144]

254 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 51-3. Yellowness Index after Xenon Exposure of Various UV-Stabilized PVC Formulations.[144]

10

8

6

4

2

01.0%

UVA #12.0%

UVA #2

Xenon Exposure (8000 hrs)

1.0%Tinuvin XT 833

Yel

low

ness

Inde

x

Chapter 52

Chlorinated Polyvinyl Chloride

Category: Vinyl, thermoplastic.

General Properties: Chlorinated polyvinyl chloride(CPVC) has physical properties similar to PVC, butoffers higher heat deflection properties for extendedtemperature range uses.

Graph 52-1. Drop Weight Impact Strength Retained after Florida Outdoor Weathering Exposure of CPVC.

Weathering Properties

CPVC has reasonable weathering properties.[145]

Chapter 53

ABS Polyvinyl Chloride Alloy

Category: Acrylonitrile-butadiene-styrene (ABS)polymer, polyvinyl chloride (PVC) compounds,thermoplastic, vinyl.

General Properties: Novatec Novaloy® 9000 is aspecialty engineering alloy of ABS/PVC and hasbeen formulated to provide excellent retention ofphysical properties upon aging.[147]

Weathering Properties

Halogen-containing polymers (e.g., PVC) arerelatively cheap and readily available materials.However, the weatherability (e.g., the light stabilityof halogen-containing polymers) is poor, leading torelatively short lifetimes, particularly in pigmentedformulations.[148]

The retention of mechanical and surface andappearance properties following exposure to an out-door environment is important. Acrylic materials

generally have exceptional weathering performance.Blends of PVC and acrylic materials may be attrac-tive in some situations.[148]

For example, compared to unmodified acrylics,acrylics modified by the addition of PVC may becheaper, have increased toughness, exhibit reducedflammability, and have desirable melt-flow proper-ties. However, while the weathering performance ofan acrylic/PVC blend is generally improved com-pared to PVC alone, the addition of PVC to acrylicsreduces the weathering performance compared tounmodified acrylics. Thus, an acrylic/PVC blendmay exhibit unacceptable color stability and degra-dation in appearance and mechanical properties fol-lowing exposure to sunlight or in weathering tests.For unmodified pigmented acrylic/PVC blends theextent to which this “chalking” occurs is depen-dent upon the amount of PVC present in the blend,but even at concentrations of <20% wt/wt PVC anoticeable color shift, �E, occurs after 6000 hoursof exposure.[148]

258 The Effects of UV Light and Weather on Plastics and Elastomers

Table 53-1. Color Change after Accelerated QUV Weathering of Novatec Novaloy® 9000 ABS/PVC Alloy

Chapter 54

Acrylic (PMMA) Polyvinyl Alloy

Category: Acrylic, thermoplastic, vinyl, poly-methylmethacrylate (PMMA).

General Properties: Novatec Kydex® 550 andKydex® 510 are weatherable acrylic/PVC sheets.

Weathering Properties

Kydex® 550 and Kydex® 510 offer superiorresistance to UV rays and will show no significantcolor degradation when exposed to UV rays.[150]

Chapter 55

Polycarbonate ABS Alloy

Category: ABS polymer, polycarbonate, thermo-plastic.

General Properties: Bayer Bayblend® PC/ABS isBayer’s trade name for a family of amorphous,thermoplastic polymer blends based on polycarbon-ate (PC) and acrylonitrile-butadiene-styrene (ABS).Dow Automotive Pulse® engineering resins arePC/ABS alloys.

Table 55-1. Color Change,�E, after HPUV and Xenon Arc Accelerated Indoor Exposure of Dow ChemicalPulse 1745

Weathering Properties

Due to the UV resistance of Bayblend resins,molded parts will retain good mechanical andcolor hold properties without light-protectivecoatings.[151]

Chapter 56

Biodegradable Polyethylene Films

Category: Polyethylene (PE), starch.

General Properties: PE agricultural films can bestarch modified for biodegradability.

Studies in Taiwan that began in 1991 have shownthat degradable PE films can help lessen the problemof plastic wastes in agriculture. The starch contentof degradable PE films is a major factor in theirdegradability.[153]

Degradation Rate

The degradation rate was influenced by themulching date, content of starch incorporated intothe films, and the type of soil.[153]

Macro- and micro-environmental changes indifferent seasons affect the degradation timeof the tested degradable plastic films. Thebio/photodegradable silver-black colored PE filmscontaining 20% starch from USI Far East Corpora-tion degraded after 56, 83, 38, and 33 days whenthey were used as mulch in autumn (October 1991),winter (December 1991), spring (April 1992), andsummer (August 1992), respectively. The greater theamount of starch incorporated, the faster the filmsdegraded.[153]

The degradation rate reached 93.5% forbiodegradable films buried in slate alluvial soil, butit was less for films buried in red soil.[153]

264 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 56-1. Degradation of Various Mulching Films after Exposure to Natural Solar Radiation atDifferent Periods[153]

% of Fracture Days from Mulching MulchingMulching Films in Films (%) to Appearance of Investigation

Crack in Film

IUPEC (B) 1.89 47Bio Multi B (B) 3.33 45Eco Green B (B) 18.5 31Cell Green multi (B) 3.13 30 8/9/2000–18/12/2000Kiemaru (B) 3.77 47ECM (B) 3.70 43Novon (B) 80.8 12

Plastor #221 (P) 61.4 20Plastor #131 (P) 0.49 46Plastor #19 (P) 0.55 68Plastor #12 (P) 1.36 46 30/9/1999–30/12/1999Green choice (D) 25.3 20Ecolene (D) 0.72 60Mater-Bi (B) 48.7 52Regular PE 0 —

Ecolene (D) 1.01 0

Green choice (D) 66.6 19Neogreenpol (B) 40.1 13Novon (B) 83.9 14 04/11/1998–01/02/1999Recycle paper (B) 48.1 30Paper film (B) 21.3 32Regular PE 0 —

Bioflexs (B) 67.0 1

Green choice (D) 50.7 9Paper film (B) 15.3 16Recycle paper (B) 11.9 16 11/10/1997–02/02/1998Cascades (paper) (B) 22.5 58Young-1 (B) 25.1 16Young-3 (B) 35.7 16Regular PE 0 —

Paper film (B) 14.6 7

Recycled paper (B) 48.0 77Polystarch (D) 0.08 77Green choice (D) 23.5 11 08/11/1996–16/2/1997Oligostarch (D) 2.02 68Ecolence (D) 0 —Regular PE 0 —

Ecostorplus (D) 4.96 30

KK film (D) 73.1 19 27/10/1995–29/12/1995Recycle paper (B) 6.8 22Regular PE 0 —

Ecolene (D) 100 —

Ecostrplus (D) 86.5 —KK-1 (D) 100 5/12/1994–10/2/1995KK-2 (D) 100 —Polymer-M (P) 0 —Regular PE 0 —

Ecostarplus (D) 65.8 —

Ecostar (D) 35.3 —Plastor-132b (P) 11.2 — 9/10/1993–15/3/1994Polygrade (P) 25.7 —Regular PE 0 —

P, photodegradable; D, disintegradable; B, biodegradable.

56: Biodegradable Polyethylene Films 265

Table 56-2. Days From Mulching to Appearance of Fracture in Film[153]

Mulching Days from Mulching to Air Temp Total Sunshine Cumulative LightDate Appearance of Fracture in Film* (◦C) (hrs) Energy (g/cal/cm2)

9 October 1991 56 23.2 267.1 14,077

30 December 1991 83 18.5 415.5 20,803

28 April 1992 38 26.2 224.2 12,000

3 August 1992 33 28.9 173.6 11,198

*Data obtained from Photo/biodisintegradable PE films incorporated with 20% starch.

Table 56-3. Degradation of Mulching Films Incorporated with Different Starch Content[153]

Starch Content % of Fracture in Film

Incorporated in Film (%)First Crop* Second Crop†

5% 11.2 15.1

10% 17.8 26.9

15% 20.6 25.1

20% 28.4 41.5

Regular 0 0

*19 August–9 October 1992.†29 December 1992–4 May 1993.

Graph 56-1. Weight Loss of Mater-Bi Biodegradable Film after Burying in Various Soils.[153]

100.0

50.0

0.030 45 60

Days after Burying

Wei

ght L

oss

in F

ilm (

%)

Red sils

Sandstone-shale alluvial soil

Slate alluvial soils

266 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 56-2. Elongation Retained after Xenon Weatherometer Exposure of Starch-Modified Low DensityPolyethylene (LDPE) Film.

Graph 56-3. Elongation Retained after Composting of Starch-Modified LDPE Film.

56: Biodegradable Polyethylene Films 267

Graph 56-4. Starch Content Retained after Burial of Ecostar Starch-Modified PE Film.

Chapter 57

Starch Synthetic Resin Alloy

Category: Biodegradable plastic.

General Properties: Novamont Mater-Bi™ con-tains starch (nongenetically modified) blended withpetroleum-based biodegradable polymers (e.g. poly-caprolactone, which provides water resistance andstrength). Mater-Agro is an entirely biodegradablefilm that, with the action of microorganisms underaerobic conditions and with suitable humidity, bio-degrades completely, changing into water and carbondioxide.[156]

Biodegradability

Biodegradability is a characteristic of naturalsubstances and materials being assimilated by micro-organisms and thus introduced into the naturalcycles. When natural organic materials go into theground, they tend to decompose progressively andfinally disappear.[156]

Chapter 58

Thermoset Polyester

Category: Thermoset, polyester.

General Properties: Thermoset polyesters, orunsaturated polyesters (UPES), are extremelyversatile materials.

Polyester coatings are suitable for outdooruse where considerable amount of sunlight ispresent. They have good weathering and mechanicalproperties.[157] Thermosetting powders are primarilycomposed of relatively high molecular weight solidresins and a cross-linking agent. Thermoset pow-ders are used for a wide variety of decorative andprotective applications.[158]

Polyester Powder

Polyester resins are used to formulate urethanepolyesters and polyester triglycidyl isocyanuratematerials.[158]

Urethane Polyesters

Urethane-cured polyester powders have excel-lent resistance to outdoor environments. A smooth,

thin film that resists weathering and physical abusemakes the urethane polyesters a popular finish forhigh quality products.[158]

Polyesters are generally less sensitive to physicaldegradation from UV light than aromatic urethanes,or two-component epoxies.[159]

Weathering Properties:UV Stabilization

With UV light exposure, UPES undergo colorchange, loss of gloss, cracking, and other UV-induced deterioration. The UPES manufacturingprocess employs two different kinds of curing sys-tems: the hot cure and the cold cure. In the hot curesystem, the use of a combination of Ciba Tinuvin®

328 and Ciba Chimassorb® 81 provides good colorstability to UPES after exposure to long-term weath-ering conditions.[160]

272 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Graph 58-1. Yellowness Index after Xenon Arc Weathering of Unsaturated Polyester.[160]

25

20

15

10

5

00 1000 2000 3000 4000

Yello

wne

ss In

dex

Exposure Time (hrs)

Control

0.3% Chimassorb 81

0.15% Tinuvin 2380.15% Chimassorb 81

Note: Xenon Arc Weathering, ISO 4892-2, dry; UPES prepared by hot curing.

Chapter 59

Polyurethane Reaction InjectionMolding System

Category: Polyurethane, thermoset.

General Properties: Reaction injection molding(RIM) takes its name from a chemical reaction thatoccurs within the forming tool. The plastics endup as thermosets, either polyurethanes or foamedpolyurethanes. The two components that produce thepolyurethane are mixed just prior to injection into thetool.[161]

Recticel Colo-Fast® is a light- and heat-stablepolyurethane designed for RIM technology. Basedon aliphatic isocyanates, Colo-Fast® is integrally col-ored and does not require post-painting or in-moldcoating to prevent UV degradation of the exposedpolyurethane.[162]

Weathering Properties

Colo-Fast® LM 161 has been subjected to anumber of artificial weathering (e.g., weatherometer)tests as well as outdoor exposure in Florida. Typi-cally, there is a slight increase in gloss of a mediumgloss sample in most tests without polishing thesample. This is due to smoothing of the tiny irreg-ularities in the surface (faithfully reproducing themold texture) which gave the sample its originalmedium gloss level. On extremely long exposure,

longer than required by automotive specifications,there is some dulling of the surface, but this canbe restored by polishing with common automotivecleaners. No waxing is needed.[163]

After artificial exposure there is little changein gloss even without washing or polishing. Glossincreases slightly in samples exposed for ninemonths in Florida. These samples must be washedto remove the dirt that accumulates under outdoorconditions. No surface cracking or discolorationwas observed after artificial weathering or Floridaexposure.[163]

Samples without pigment have also beenexposed to artificial weathering conditions. Evenwithout pigment, the samples show only slightdiscoloration and gloss change, demonstrating thematerial’s inherent weatherability.[163]

EMMAQUA (referred to as Sun 10 Testingby Recticel) testing was conducted on Colo-Fast®

RIM polyurethane and several competitive materi-als. After the equivalent of five years of outdoorweathering, the materials were compared visually ona scale of 10 (best) to 1 (poor). Colo-Fast® remainsunchanged with a rating of 10 out of 10 for the entiretest. After just three years, the PVC samples showedwarping and after four years they were brittle. Thestabilized aromatic rates 5 out of 10 after five years.The aromatic with in-mold coated (IMC) paint showsa wear rating of only 2 out of 10.[162]

274 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 59-1. Surface and Appearance Changes after Xenon Arc Accelerated Weathering Exposure(GM Specifications) of Recticel Colo-Fast® Polyurethane RIM System

59: Polyurethane Reaction Injection Molding System 275

Table 59-2. Surface and Appearance Changes after Xenon Arc Accelerated Weathering Exposure(Japanese Specifications) of Recticel Colo-Fast® Polyurethane RIM System

276 The Effects of UV Light and Weather on Plastics and Elastomers

Table 59-3. Surface and Appearance Changes after Fadeometer Accelerated Weathering Exposure ofRecticel Colo-Fast® Polyurethane RIM System

Graph 59-1. Change in Color, �b, after Florida Outdoor Weathering Exposure of Recticel Colo-Fast®

Polyurethane RIM System and Aromatic Polyurethane.

59: Polyurethane Reaction Injection Molding System 277

Graph 59-2. Gloss Retained after QUV Weathering Exposure of Recticel Colo-Fast® Polyurethane RIMSystem.

Graph 59-3. Gloss Retained after Sunshine Carbon Arc Weathering Exposure of Recticel Colo-Fast®

Polyurethane RIM System.

278 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 59-4. Results of Visual Inspection after EMMAQUA Accelerated Exposure of Recticel Colo-Fast®

Polyurethane RIM System and Several Other Materials.[162]

10

5

0Year

1Year

2Year

3Year

4Year

5

Colo-Fast

PVC

Stabilized Aromatic

Aromatic IMC

Sun 10 TestingVisual Code

Note: EMMAQUA Fresnel-reflecting concentrator as per SAE J1961; total exposure: 1540 MJ/m2 (total UV 295–385 nm);308 MJ/m2 = 1 equivalent Florida year; total: 838,000 langleys.

Chapter 60

Thermoplastic Elastomers: Overview

Thermoplastic elastomers (TPEs) are a diversefamily of rubber-like materials that, unlike conven-tional vulcanized rubbers, can be processed andrecycled like thermoplastic materials. TPEs behavelike elastomeric rubber at room temperature (i.e.,durable and bouncy), but can also be melted andeasily formed into shapes when they are heatedlike plastics. Thermo- means “heat” and plasticmeans “moldable.” Elastomer means “rubber.” Soa TPE is a rubber material that can be molded whenit is heated.[166] A TPE generally contains >50%elastomer.

Most types of elastomers are difficult to processbecause they are cross-linked. But TPEs are rub-bery without being cross-linked, making them easyto process.[166]

Many TPEs are copolymers, a material madefrom two different constituents (monomers)—oneof which is a rubber and the other a plastic. BecauseTPEs can be melted, they are recyclable. But becausethey form cross-links that are not permanent whenthey are cooled, this makes them rubbery.[166]

There are two main kinds of TPEs, ionomersand block copolymers. An ionomer is a polymerthat has a small number of ionic groups along its

backbone chain. A block copolymer is a polymerthat has more than one section, or block. For exam-ple, a chain of SBS rubber is made of a shortblock of polystyrene followed by a longer block ofpolybutadiene, followed by another short block ofpolystyrene.[166]

“The big difference between a cross-linked rub-ber and a thermoplastic elastomer is that in a cross-linked rubber the polymer chains are bonded to eachother through covalent bonds, that is, the bonds thatform when two atoms share a pair of electrons. Ineither type of thermoplastic elastomer, the polymerchains are held together by bonds that are weakerthan covalent bonds. In the case of ionomers itis dipole-dipole interactions that bind the polymerchains to one another. In the block copolymer dis-persion forces are at play. But in both ionomers andblock copolymers, forces much weaker than those ofthe covalent bonding ‘cross-link’the polymer chains.Because much weaker forces are binding the chainstogether, breaking them apart is much easier, so easythat all it takes is the right amount of heat to sepa-rate the chains from each other, making the materialprocessable again.”[167]

Chapter 61

Chlorinate Polyethylene Elastomer

Category: Elastomer, thermoplastic, TPE.

General Properties: Dow Chemical CompanyTyrin® chlorinated polyethylene elastomer is oftenused as a modifier for PVC.[168]

Weathering Properties

Modified PVC compounds made with Tyrin®

show excellent resistance to weathering.[168]

Sunlight, ozone, and oxygen can commonlycause environmental degradation of many elas-tomers by attacking both saturated and (especially)unsaturated sites along the polymer chain. BecauseTyrin products have a saturated molecular backbone,they are not as susceptible to such attacks as aremany other elastomers.[169]

Long-term exposures of properly formulatedrubbers made with Tyrin elastomers have shown nocracking when tested in an ozone atmosphere orwhen exposed to outdoor weathering.[169]

Chapter 62

Olefinic Thermoplastic Elastomer

Category: Elastomer, thermoplastic.

General Properties: Thermoplastic olefins (TPOs)are generally <50% elastomer with common elas-tomer content between 10–30%.

Advanced Elastomer Systems, LP, an ExxonMobil Chemical Affiliate, offers Santoprene™ ther-moplastic vulcanizates (TPVs), a series of high-performance elastomers combining the desirablecharacteristics of vulcanized rubber such as flexibil-ity and low compression set with the processing easeof thermoplastics.[170]

PolyOne Forprene® is the brand name of afamily of compounds that consists of a polyolefinphase with a dynamically cured ethylene-propylenediene monomer phase closely dispersed in the poly-olefin. This design gives unique rubber-like proper-ties with the advantage of thermoplastic processingtechniques.[171]

Dow Chemical Company’s Engage™ thermo-plastic elastomers are ethylene-octene copolymersproduced via advanced Insite™ catalyst and processtechnology.[172]

Weathering Properties

Forprene® has good resistance to ozone, UVradiation, and weathering exposure which is due tothe saturated elastomeric phase.[171]

Santoprene™ TPV black UV stable gradesexhibit good retention of both physical and appear-ance properties after long exposure periods usingmany common weathering tests.

Conventional Arizona Aging: Santoprene™ TPVblack UV grades show a color change (�E) of lessthan 3 for the 48-month exposure. The softer gradesof general-purpose Santoprene TPV perform wellduring this exposure, but the harder grades showa continuous decrease in color stability with time.

The hardness change of these grades shows a slightdeterioration over the same time period, the softergrades retaining their hardness. All of the materialstested maintained reasonably good tensile strengthand elongation over the 48-month period.[173]

Conventional Arizona Aging with Spray:Santoprene™ TPV black UV grades show a colorchange (�E) of less than 3 for most grades for the48-month period. The softer grades of Santoprene™

show minor hardness changes, while the hardergrades continue to increase in hardness with expo-sure time. Most of the materials maintain a signi-ficant tensile strength during the exposure period.Both the black UV-stable and general-purpose gradesof Santoprene™ maintain most of their elongationduring exposure.[173]

Conventional Florida Aging: Since Florida test-ing has a higher average humidity, the exposure isharsher on some materials. Humidity has a strongeffect on the color of the harder grades of general-purpose Santoprene™ TPV materials but a minoreffect on black UV-stable grades, especially overlong exposures. The hardness changes are minor,with the harder grades showing the most increase.Most of the materials maintain their tensile strength.The softer grades of general-purpose Santoprene™

TPV do not retain their elongation properties as wellas the black UV-stable grades.[173]

Conventional FloridaAging with Spray: The colorchange for black UV-stable grades of Santoprene™

TPV is very small. General-purpose (harder) gradesof thermoplastic rubber have a large �E. Signifi-cant hardness changes occur in the harder grades ofgeneral-purpose and black UV-stable grades. Softergrades exhibit only minor hardness changes. Ten-sile strength retention is good for most of the mate-rials, Santoprene™ TPV general-purpose grades havea tensile strength retention rate similar to that of black

284 The Effects of UV Light and Weather on Plastics and Elastomers

UV-stable grades. General-purpose harder grades ofSantoprene™ TPV show a continuous decrease inelongation with exposure time.[173]

Outdoor Accelerated ExposureTesting

Equatorial Mount with Mirrors for Accele-ration (EMMA): The general-purpose grades ofSantoprene™ TPV show a greater color change thanthe black UV-stable grades. Most of the materialsexhibit good retention of tensile strength with theexception of harder general-purpose Santoprene™

TPV grades which show minor deterioration.Elongation of harder grades of general-purposeSantoprene™ TPV exhibits significant deteriorationduring the exposure period. Soft general-purposeand UV-stable grades continue to retain elongationproperties.[173]

Equatorial Mount with Mirrors for Accele-ration Plus Water (EMMAQUA): This exposureis the harshest. Softer, black UV-stabilized gradesare the only materials that show minor changes incolor. The rest of the materials show major colorchanges. The hardness change of most materialsis minor. All the materials suffer a significant loss

in tensile strength. The general-purpose grades ofSantoprene™ TPV do not retain their tensile strengthas well as the black UV-stable grades. Elongationretention is very difficult for the harder grades ofSantoprene™ TPV. The softer grades have betterretention of elongation.[173]

Xenon Arc: Most UV grades of Santoprene™ TPVretain 90% or more of their tensile properties after3000 hours and 80% or more after 5000 hours.The harder grades of general-purpose Santoprene™

TPV show a significant color change with exposurelevel. The rest of the materials have a color change(�E) of less than 3. Only minor changes in hard-ness are seen with increased exposure. Retentionof tensile strength is good for all materials. BlackUV-stable Santoprene™ TPV has increased tensilestrength retention when compared to the general-purpose grades. Santoprene™ TPV grades show goodelongation. The color retention for the softer blackUV-stable grades is excellent up to 2500 kJ/m2.The hardest grade of this material, 123-50, showssignificant color change with exposure.[173]

Xenon Arc SAE J1960: Most Santoprene™ TPVblack high-flow grades exhibit good retention ofphysical and appearance properties after 2500 kJ/m2

exposure to exterior automotive xenon arc testing.[174]

62: Olefinic Thermoplastic Elastomer 285

Weathering Properties by Material Supplier Trade Name

Table 62-1. Retention of Mechanical Properties after Xenon Arc Exposure for Black UV Grades ofAdvanced Elastomer Systems Santoprene™ TPV

Material Family Olefinic Thermoplastic Elastomer

Material Supplier Advanced Elastomer Systems Santoprene™ TPV

Features Black UV Grades

Reference Number 173

MATERIAL CHARACTERISTICS

Grades 121-67 121-73 121-80

Shore A Hardness 67 73 80

Shore D Hardness

Exposure Conditions Xenon Arc Exposure, SAE J1885

Exposure Time (hrs) 3000 5000 3000 5000 3000 5000

PROPERTIES RETAINED (%)

Tensile Strength 91 83 78 73 81 74

Elongation 98 93 75 72 78 74

100% Modulus 107 110 105 102 102 97

MATERIAL CHARACTERISTICS

Grades 121-87 123-40 123-50

Shore A Hardness 87

Shore D Hardness 40 50

Exposure Conditions Xenon Arc Exposure, SAE J1885

Exposure Time (hrs) 3000 5000 3000 5000 3000 5000

PROPERTIES RETAINED (%)

Tensile Strength 88 87 94 96 92 95

Elongation 89 84 92 89 93 91

100% Modulus 99 104 99 109 105 107

286 The Effects of UV Light and Weather on Plastics and Elastomers

Table 62-2. Material Properties after Arizona Outdoor Exposure for Black UV Grades of AdvancedElastomer Systems Santoprene™ TPV

Material Family Olefinic Thermoplastic Elastomer

Material Supplier Advanced Elastomer Systems Santoprene™ TPV

Features Black UV Grades

Reference Number 173

Exposure Conditions Arizona Outdoor Exposure, SAE J1545

Hardness Test Method ASTM D2240

Tensile Strength Test Method ASTM D412

Elongation Test Method ASTM D412

MATERIAL CHARACTERISTICS

Grades 121-67 121-73 121-80 121-40 101-64 103-40

Shore A Hardness 67 73 80 40 64

Shore D Hardness 40

COLOR CHANGE (�E)

6 months 3.6 4.6 1.6 0.3 5.2 3

12 months 2.9 3.3 1.1 1.4 3.1 7.3

24 months 1.4 2 1.4 2.7 1.7 8.3

48 months 1.2 1.6 1.7 2.8 1.5 11.9

CHANGE IN HARDNESS

Shore A (6 months) −1 2 3 2

Shore D (6 months) 5 4

Shore A (12 months) −1 3 5 2

Shore D (12 months) 6 3

Shore A (24 months) −1 −1 4 3

Shore D (24 months) 5 3

Shore A (48 months) 1 4 6 3

Shore D (48 months) 10 8

TENSILE STRENGTH RETAINED (%)

6 months 88 85 80 97 75 95

12 months 83 78 77 94 74 98

24 months 87 79 76 99 75 92

48 months 76 77 63 97 75 96

ELONGATION RETAINED (%)

6 months 83 84 80 94 69 95

12 months 84 81 79 92 72 95

24 months 86 80 75 98 74 91

48 months 93 83 77 94 73 94

62: Olefinic Thermoplastic Elastomer 287

Table 62-3. Material Properties after Arizona Outdoor Exposure with Spray for Black UV Grades ofAdvanced Elastomer Systems Santoprene™ TPV

Material Family Olefinic Thermoplastic Elastomer

Material Supplier Advanced Elastomer Systems Santoprene™ TPV

Features Black UV Grades

Reference Number 173

Exposure Conditions Arizona Outdoor Exposure with Spray, SAE J1545

Tensile Strength Test Method ASTM D412

Elongation Test Method ASTM D412

Hardness Test Method ASTM D2240

MATERIAL CHARACTERISTICS

Grades 121-67 121-73 121-80 121-40 101-64 103-40

Shore A Hardness 67 73 80 40 64

Shore D Hardness 40

COLOR CHANGE (�E)

6 months −1 4 3 5 1 3

12 months −1 −4 4 5 1 1

24 months −1 2 5 6 2 2

48 months 4 5 9 2 7

CHANGE IN HARDNESS

Shore A (6 months) −1 4 3 1

Shore D (6 months) 5 3

Shore A (12 months) −1 −1 4 2

Shore D (12 months) 5 1

Shore A (24 months) −1 −1 4 1

Shore D (24 months) 5 3

Shore A (48 months) 4 5 2

Shore D (48 months) 9 7

TENSILE STRENGTH RETAINED (%)

6 months 83 58 76 96 74 92

12 months 89 77 76 97 77 93

24 months 90 82 79 101 70 97

48 months 84 80 100 75 99

ELONGATION RETAINED (%)

6 months 77 75 79 87 72 93

12 months 88 78 82 85 74 91

24 months 89 82 83 96 73 97

48 months 87 87 98 76 97

288 The Effects of UV Light and Weather on Plastics and Elastomers

Table 62-4. Material Properties after Florida Outdoor Exposure for Black UV Grades of AdvancedElastomer Systems Santoprene™ TPV

Material Family Olefinic Thermoplastic Elastomer

Material Supplier Advanced Elastomer Systems Santoprene™ TPV

Features Black UV Grades

Reference Number 173

Exposure Conditions Florida Outdoor Exposure

Tensile Strength Test Method ASTM D412

Elongation Test Method ASTM D412

Hardness Test Method ASTM D2240

MATERIAL CHARACTERISTICS

Grades 121-67 121-73 121-80 123-40 101-64 103-40

Shore A Hardness 67 73 80 64

Shore D Hardness 40 40

COLOR CHANGE (�E)

6 months 5.4 5.6 2.3 1.2 6.3 2.7

12 months 4.8 5 2.1 0.9 4.4 9.1

24 months 1.1 1.5 0.4 0.9 1.2 11.2

48 months 1 1.3 2.4 3.2 1.7 11.7

CHANGE IN HARDNESS

Shore A (6 months) −2 1 4 0

Shore D (6 months) 4 2

Shore A (12 months) −2 1 2 1

Shore D (12 months) 6 3

Shore A (24 months) 0 −3 5 2

Shore D (24 months) 9 8

Shore A (48 months) 1 3 3 1

Shore D (48 months) 7 5

TENSILE STRENGTH RETAINED (%)

6 months 89 82 84 97 78 98

12 months 93 85 81 97 80 97

24 months 82 81 78 98 69 95

48 months 93 88 87 96 73 98

ELONGATION RETAINED (%)

6 months 87 86 88 98 78 100

12 months 92 87 83 99 80 96

24 months 80 86 84 96 75 97

48 months 96 93 92 94 78 99

62: Olefinic Thermoplastic Elastomer 289

Table 62-5. Material Properties after Florida Outdoor Exposure with Spray for Black UV Grades ofAdvanced Elastomer Systems Santoprene™ TPV

Material Family Olefinic Thermoplastic Elastomer

Material Supplier Advanced Elastomer Systems Santoprene™ TPV

Features Black UV Grades

Reference Number 173

Exposure Conditions Florida Outdoor Exposure with Spray

Hardness Test Method ASTM D2240

Tensile Strength Test Method ASTM D412

Elongation Test Method ASTM D412

MATERIAL CHARACTERISTICS

Grades 121-67 121-73 121-80 123-40 101-64 103-40

Shore A Hardness 67 73 80 64

Shore D Hardness 40 40

COLOR CHANGE (�E)

6 months 3.2 3.9 1.4 1.5 6.6 4.8

24 months 3 3.4 6.5 1.3 2.6 8.5

48 months 1.8 1.6 2.1 2.6 1.43 16.2

CHANGE IN HARDNESS

Shore A (6 months) 0 3 4 0

Shore D (6 months) 4 0

Shore A (24 months) 1 2 5 1

Shore D (24 months) 9 7

Shore A (48 months) 1 4 3 3

Shore D (48 months) 8 7

TENSILE STRENGTH RETAINED (%)

6 months 89 77 84 99 79 96

24 months 85 81 80 101 71 97

48 months 93 84 87 103 71 65

ELONGATION RETAINED (%)

6 months 90 80 89 99 83 98

24 months 86 82 82 97 69 97

48 months 93 86 90 100 75 48

290 The Effects of UV Light and Weather on Plastics and Elastomers

Table 62-6. Material Properties after EMMA Accelerated Exposure with Spray for Black UV Grades ofAdvanced Elastomer Systems Santoprene™ TPV

Material Family Olefinic Thermoplastic Elastomer

Material Supplier Advanced Elastomer Systems Santoprene™ TPV

Features Black UV Grades

Reference Number 173

Exposure Conditions EMMA Accelerated Exposure, SAE J1545

Hardness Test Method ASTM D2240

Tensile Strength Test Method ASTM D412

Elongation Test Method ASTM D412

MATERIAL CHARACTERISTICS

Grades 121-73 123-40 101-73 103-40

Shore A Hardness 73 73

Shore D Hardness 40 40

COLOR CHANGE (�E)

6 months 3.4 8.3 5.8 15

12 months 2.3 8.9 5.5 14.6

24 months 2.5 8.7 5.2 12.2

CHANGE IN HARDNESS

Shore A (6 months) 2 8

Shore D (6 months) 7 3

Shore A (12 months) 2 5

Shore D (12 months) 5 3

Shore A (24 months) −3 5

Shore D (24 months) 3 2

TENSILE STRENGTH RETAINED (%)

6 months 82 94 82 86

12 months 85 100 84 82

24 months 95 101 85 58

ELONGATION RETAINED (%)

6 months 72 80 67 69

12 months 81 79 67 65

24 months 52 76 50 6

62: Olefinic Thermoplastic Elastomer 291

Table 62-7. Material Properties after EMMAQUA Accelerated Exposure for Black UV Grades ofAdvanced Elastomer Systems Santoprene™ TPV

Material Family Olefinic Thermoplastic Elastomer

Material Supplier Advanced Elastomer Systems Santoprene™ TPV

Features Black UV Grades

Reference Number 173

Exposure Conditions EMMAQUA Accelerated Exposure, SAE J1545

Hardness Test Method ASTM D2240

Tensile Strength Test Method ASTM D412

Elongation Test Method ASTM D412

MATERIAL CHARACTERISTICS

Grades 121-73 123-40 101-73 103-40

Shore A Hardness 73 73

Shore D Hardness 40 40

COLOR CHANGE (�E)

6 months 3.6 9.5 6.8 15

12 months 3 8.4 5.5 14.9

24 months 2.1 7.3 5.2 9.5

CHANGE IN HARDNESS

Shore A (6 months) 3 7

Shore D (6 months) 5 2

Shore A (12 months) 4 5

Shore D (12 months) 7 2

Shore A (24 months) −5 4

Shore D (24 months) 0 −3

TENSILE STRENGTH RETAINED (%)

6 months 88 98 87 88

12 months 87 114 90 75

24 months 55 31 57 11

ELONGATION RETAINED (%)

6 months 85 82 77 75

12 months 66 73 62 61

24 months 68 2 49 1

292 The Effects of UV Light and Weather on Plastics and Elastomers

Table 62-8. Material Properties after Xenon Arc Exposure for Black UV Grades of Advanced ElastomerSystems Santoprene™ TPV

Material Family Olefinic Thermoplastic Elastomer

Material Supplier Advanced Elastomer Systems Santoprene™ TPV

Features Black UV Grades

Reference Number 173

Exposure Conditions Xenon Arc Exposure, SAE J1885

Hardness Test Method ASTM D2240

Tensile Strength Test Method ASTM D412

Elongation Test Method ASTM D412

MATERIAL CHARACTERISTICS

Grades 121-67 121-73 121-80 123-40 101-64 103-40

Shore A Hardness 67 73 80 64

Shore D Hardness 40 40

COLOR CHANGE (�E)

3000 hrs 1.5 2 2.3 2.7 7.8 5.3

5000 hrs 2 2.1 6.5 2.1 2.5 9.5

CHANGE IN HARDNESS

Shore A (3000 hrs) 3 2 4 1

Shore D (3000 hrs) 5 3

Shore A (5000 hrs) 2 2 5 1

Shore D (5000 hrs) 7 3

TENSILE STRENGTH RETAINED (%)

3000 hrs 91 78 81 94 61 88

5000 hrs 83 73 74 96 64 84

ELONGATION RETAINED (%)

3000 hrs 98 75 78 93 57 88

5000 hrs 93 72 74 90 67 84

62: Olefinic Thermoplastic Elastomer 293

Table 62-9. Material Properties after Xenon Arc SAE J1960 Exterior Automotive Testing for AdvancedElastomer Systems Santoprene™ TPV High-Flow Grades

Material Family Olefinic Thermoplastic Elastomer

Material Supplier Advanced Elastomer Systems Santoprene™ TPV

Features High-Flow Grades

Reference Number 173

Exposure Conditions SAE J1960 Exterior Automotive

Hardness Test Method ASTM D2240

Tensile Strength Test Method ASTM D412

Elongation Test Method ASTM D412

Color Test Method SAE J1545

MATERIAL CHARACTERISTICS

Grades 121-50 M100 121-62 M100 121-75 M100

Shore A Hardness 50 62 75

COLOR CHANGE (�E)

600 kJ/m2 0.7 0.8 0.9

1240 kJ/m2 1.0 0.4 1.3

1800 kJ/m2 0.7 1.3 1.2

2500 kJ/m2 2.4 1.8 1.8

CHANGE IN HARDNESS (SHORE A)

600 kJ/m2 2 3 4

1240 kJ/m2 3 4 5

1800 kJ/m2 2 5 4

2500 kJ/m2 2 4 5

TENSILE STRENGTH (% LOSS)

600 kJ/m2 12 11 8

1240 kJ/m2 12 16 5

1800 kJ/m2 14 21 11

2500 kJ/m2 11 19 7

ELONGATION CHANGE (% LOSS)

600 kJ/m2 14 13 10

1240 kJ/m2 12 22 7

1800 kJ/m2 12 26 12

2500 kJ/m2 7 24 12

294 The Effects of UV Light and Weather on Plastics and Elastomers

Table 62-10. Material Properties after UV-CON Accelerated Indoor Exposure of PolyOne Forprene®

Olefinic Thermoplastic Elastomer

62: Olefinic Thermoplastic Elastomer 295

Table 62-11. UV Resistance after Accelerated UV Light Exposure of PolyOne Forprene® OlefinicThermoplastic Elastomer

Table 62-12. Ozone Resistance of PolyOne Forprene® Olefinic Thermoplastic Elastomer

296 The Effects of UV Light and Weather on Plastics and Elastomers

Table 62-13. Ozone Resistance of Advanced Elastomer Systems Santoprene™ Olefinic ThermoplasticElastomer

62: Olefinic Thermoplastic Elastomer 297

Table 62-14. Ozone Resistance of Dow Chemical Company’s Engage™ OlefinicThermoplastic Elastomer

298 The Effects of UV Light and Weather on Plastics and Elastomers

Table 62-15. Ozone Resistance of Advanced Elastomer Systems Santoprene™ Black Olefinic Thermo-plastic Elastomer

Graph 62-1. Carbonyl Formation after Xenon Arc Weatherometer Exposure of Dow Chemical Company’sEngage™ Olefinic Thermoplastic Elastomer.

62: Olefinic Thermoplastic Elastomer 299

Graph 62-2. Decrease in Molecular Weight after Xenon Arc Weatherometer Exposure of Dow ChemicalCompany’s Engage™ Olefinic Thermoplastic Elastomer.

Chapter 63

Polyester Thermoplastic Elastomer

Category: Polyester, thermoplastic, elastomer,TPE, TP.

General Properties: DuPont Hytrel® thermoplasticpolyester elastomers are block copolymers consist-ing of a hard (crystalline) segment of polybutyleneterephthalate and a soft (amorphous) segment basedon long-chain polyether glycols. Its properties aredetermined by the ratio of hard to soft segments andby the makeup of the segments. Hytrel® combinesmany of the most desirable characteristics of high-performance elastomers and flexible plastics. Thevarious grades of Hytrel® exhibit a wide range offlexibility/stiffness and processing capabilities.[180]

Weathering Properties

For outdoor applications, Hytrel® should be pro-tected from UV attack. The most efficient methodis the incorporation of low levels of carbon black.Where nonblack products are desired, weather pro-tection is most efficiently obtained by incorporationof UV stabilizers alone (natural) or in combinationwith low levels of colored pigments.[181]

Excellent resistance to degradation is observedin weatherometer and Florida aging studies withspecimens 1.9 mm (0.075′′) thick and containing0.5% and 1% carbon black. These levels of carbonblack provide good protection for thick sections; for

thinner parts, additional protection is needed. Forfilms 0.25 mm (0.010′′) thick, up to 3% carbon blackis needed for protection from UV light.[181]

Specimens 1.9 mm (0.075′′) thick behaved verywell under weatherometer and Florida aging stu-dies with as little as 0.5% black; little additionalimprovement is achieved with 1% carbon black.As sample thickness is decreased, however, higherlevels of the protective additive are required. Testsindicate that 1.9% carbon black is required for excel-lent protection in 0.25 mm (0.010′′) thick films,with somewhat compromised property retention atlower thicknesses. Some tested compounds con-tained moisture stabilizing additives such as 1.9%polycarbodiimide in addition to carbon black, whichundoubtedly compromises property retention aspredicted for similar black compounds containingno polycarbodiimide.[181]

Weathering Properties:Color Pigments

Hytrel® can be pigmented or colored using pig-ment concentrates or masterbatches as pellet-pelletblends with the virgin polymer. Other techniquessuch as liquid colorants and dusting-on of powderedpigments have also been used. Hytrel® has also beencolored by dipping in liquid dye baths.[181]

302 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 63-1. Material Properties Retained and Surface and Appearance after Florida Outdoor Weatheringfor DuPont Hytrel® Polyester Thermoplastic Elastomer

63: Polyester Thermoplastic Elastomer 303

Table 63-2. Material Properties Retained and Surface and Appearance after Florida Outdoor Weatheringfor DuPont Hytrel® 40D Polyester Thermoplastic Elastomer with Carbon Black

304 The Effects of UV Light and Weather on Plastics and Elastomers

Table 63-3. Material Properties Retained after Florida Outdoor Weathering for DuPont Hytrel® 5556Polyester Thermoplastic Elastomer with Carbon Black

63: Polyester Thermoplastic Elastomer 305

Table 63-4. Material Properties Retained and Surface and Appearance after Florida Outdoor Weatheringfor Varying Thicknesses of DuPont Hytrel® 6345 Polyester Thermoplastic Elastomer Films with CarbonBlack

306 The Effects of UV Light and Weather on Plastics and Elastomers

Table 63-5. Material Properties Retained after Carbon Arc Accelerated Weathering for DuPont Hytrel®

40D Polyester Thermoplastic Elastomer

63: Polyester Thermoplastic Elastomer 307

Table 63-6. Material Properties Retained after Carbon Arc Accelerated Weathering for DuPont Hytrel®

5556 Polyester Thermoplastic Elastomer with Varying Levels of Carbon Black

308 The Effects of UV Light and Weather on Plastics and Elastomers

Table 63-7. Material Properties Retained and Surface and Appearance after Carbon Arc AcceleratedWeathering for DuPont Hytrel® HT-X-3803 and 4056 Polyester Thermoplastic Elastomers with VaryingLevels of Carbon Black

63: Polyester Thermoplastic Elastomer 309

Table 63-8. Soil Burial and Fungus Resistance for DuPont Hytrel® Polyester Thermoplastic Elastomer

Chapter 64

Polystyrene-Butadiene-StyreneThermoplastic

Category: Styrene-butadiene, thermoplastic.

General Properties: Polystyrene-butadiene-styrene(SBS) is a hard rubber, a type of copolymer calleda block copolymer. Its backbone chain is made upof three segments. The first segment is a long chainof polystyrene, the middle segment is a long chain ofpolybutadiene, and the last segment is another longsection of polystyrene.

BASF Styrolux® is a styrene-butadiene blockcopolymer.[184]

Weathering Properties

Styrolux® has effective stabilization to inhibitaging on exposure to oxygen and high tempera-tures. In diffuse light, parts made from Styrolux®

retain their optical and mechanical properties for

many years. However, in outdoor applications thematerial can be degraded by the high energy contentof sunlight, resulting in yellowing and deteriorationof mechanical properties. Styrolux® is not recom-mended for outdoor applications. The time to onsetof yellowing can be considerably prolonged by usingUV stabilizers.[184]

UV-stabilized Styrolux® 656 C was tested nextto unstabilized Styrolux® 656 C in a Xenotest 1200under the conditions of DIN 53387—a filter sys-tem corresponding to solar radiation, a black paneltemperature of 45◦C, a relative humidity of 65%,and a dry period of 102 minutes in the cycle. TheUV-stabilized material began to show visible colorchange after 60 days of exposure, and after 120 daysthe sample was a very dull yellow. The unstabilizedStyrolux® 656 C showed visible color change after14 days of exposure, and after 120 days the samplewas bright yellow.[185]

Chapter 65

Styrenic Thermoplastic Elastomer

Category: Thermoplastic, elastomer.

General Properties: Kraton® D and G polymers arestyrenic block copolymers (SBCs) based on the feed-stocks styrene, butadiene, and isoprene. Kraton® Dpolymers have polybutadiene or polyisoprene mid-blocks that provide ultimate elasticity and flexibility.Kraton® G polymers are SBCs with a fully saturatedmidblock. They are elastic and flexible with the addi-tional benefits of enhanced oxidation and weatherresistance.[186]

Laporte AlphaGary Evoprene® G material isa styrene-ethylene-butylene-styrene block copoly-mer with a fully saturated midblock (i.e., no doublebonds) giving excellent ozone and UV resistance.

Weathering Properties

Kraton® D series rubbers are unsaturated andare therefore susceptible to attack by oxygen, ozone,and UV radiation, especially when stressed. Degra-dation is evidenced by surface crazing and hardening,or major cracking. Stabilizers should be added tothe formulation to protect the material throughoutprocessing and throughout its service life.[187]

Kraton® D rubbers contain an unsaturated rubbermidblock which is similar to natural rubber or SBR inits resistance to degradation. The two types of rub-ber midblocks—polybutadiene and polyisoprene—in Kraton® D series rubbers behave differently whenattacked by oxygen, ozone, or UV radiation. Poly-butadiene (Kraton® SBS rubbers) tends to cross-linkwith film, becoming hard and brittle. Polyisoprene(Kraton® SIS rubbers) tends to undergo chain scis-sion, whereby films become soft and tacky. Blends ofthe two types show less change on aging than eithertype alone.[187]

Kraton® G Polymer compounds exhibit goodozone resistance and can withstand prolonged out-door exposure applications.[186] They contain a lowlevel of phenolic antioxidant. Kraton® G rubbershave a saturated, olefin rubber type centerblock and

thus have good resistance to degradation. Whenproperly formulated, they have the ability to with-stand 4000 hours of weatherometer exposure withminimal change in properties. They will also passozone chamber testing without cracking or degra-dation of properties. Although the stability of thesepolymers is much better than that of the Kraton®

D series rubbers, it is good practice to includeadditional stabilizers.[187]

Kraton® G 1000 and G 4000 polymers can offerenhanced oxidation and weather resistance.[186]

The results of bothASTM 1171 andASTM D518ozone testing indicate that Kraton® rubber exhibitsoutstanding resistance to ozone.[176]

All Evoprene® G compounds have excellent UVresistance when pigmented black, but some gradesrequire extra stabilization when used in light ornatural colors. Evoprene® G shows no cracks whenozone tested (100 pphm/200 hours/20% strain) andexcellent UV resistance (1500 hours @ 40◦C QUV(black)).[188]

Weathering Properties:Stabilization

In choosing a stabilizer package for Kraton®

materials, it should be noted that the rubber networkis more susceptible to attack than the polystyrenedomains. Thus it is best to use stabilizers thatassociate primarily with the rubber network.[187]

One or more stabilizers should be added dur-ing compounding, at a level of about 0.5 phr. CibaTinuvin® P has been found to be effective at thislevel. A combination of 0.3 phr each of BASFUvinul® 400 and Ciba Tinuvin® n 326 is partic-ularly effective for most products, although it cancause discoloration in white stocks.With opaque pro-ducts, even without UV stabilizers, the addition ofup to five parts of a reflective filler such as titaniumdioxide or a light-absorbing filler such as carbonblack gives excellent protection.[187]

314 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 65-1. Ozone Resistance of Kraton® Styrenic Thermoplastic Elastomer

Chapter 66

Urethane Thermoplastic Elastomer

Category: Elastomer, polyurethane, thermoplastic.

General Properties: Dow Chemical Pellethane®

2103-80 AEF elastomer is a polytetramethyleneglycol ether-based polyurethane elastomer or ure-thane thermoplastic elastomer.[189] The NoveonEstane® 58202, Estane® 58300, Estane® 58315,and Estane® 58863 thermoplastic polyurethane elas-tomers (TPUs) are polyether-based urethane thermo-plastic elastomers.[190]

Weathering Properties

TPUs are known to have poor color stabilitywhen exposed to UV light. Pellethane® TPU resinsare based on aromatic isocyanates which absorbUV radiation. In turn, this can cause the mate-rial to become yellow. Depending on thickness, thematerial may embrittle in very thin films. Degra-dation upon UV exposure tends to limit the use ofTPUs in outdoor applications without the use ofstabilizers.[190]

Studies have supported two mechanisms forphotodegradation in methylenediphenyl diiso-cyanate (MDI) based polyurethanes involvingphoto-oxidation of the aromatic isocyanate anddirect photolytic cleavage of the urethane group.Photo-oxidation of the aromatic isocyanate mayproduce a diquinone imide. Quinone imides areprimarily responsible for the rapid yellowing ofMDI polyurethane. Subjecting aromatic radicals tooxygen results in the formation of semi-quinonegroups, which have strong UVabsorption and act as aphotostabilizing surface layer that protects the bulkpolymer.[18]

Degradation can also be caused by direct photo-lytic cleavage of the urethane group, which can occurin the absence of oxygen. It has been shown thatthis cleavage of the urethane group can result in aphoto-Fries rearrangement. Further photochemistry

of the aromatic amine photo-Fries product can leadto the formation of colored azo products, whichaccounts for the photo-induced yellowing in theabsence of oxygen. Similar to the semi-quinoneand quinone groups, the photo-Fries product is alsoan efficient UV absorber and is capable of actingas an internal filter to inhibit subsequent photo-oxidation. When irradiated in air, the distributionbetween photo-Fries products was found to be wave-length dependent, with the photo-Fries product beingdominant at wavelengths below 330–340 nm.[7]

Marked property loss is not always observedwhen aromatic TPUs are exposed to UV light. Thisis due to the equal probability of chain scission andradical recombination processes upon oxidation ofthe aromatic urethanes.[7]

In one study, infrared analysis of UV-exposedester-based urethanes showed substantial loss of aro-matic structures, urethane structures, and methylenegroup content. The samples had yellowed and losttensile properties upon UV exposure. The polyestercomponent was found to be more photostable thanthe MDI component.[7]

On the other hand, the polyether soft seg-ment is not as stable under UV exposure as thepolyester-based segments. Studies showed thatTPUsmade using polyester macroglycols maintain prop-erties better after UV exposure than those madewith polyether glycols. This study also showed thatthicker samples are less affected by UV radiation,due to limited surface exposure.[7]

An aliphatic polyurethane containing a polyethersoft segment also underwent rapid photodegradationwith catastrophic loss of molecular weight after ashort xenon arc exposure of only 231 hours. FTIRanalysis confirmed that it was the polyether compo-nent that degraded. Numerous other studies supportthe degradation effects on polyether urethanes due tooxidation and the improved resistance to oxidationof polyester urethanes.[7]

316 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties:UV Stabilization

Two methods of UV stabilization are commonlyused: UV absorbers (e.g., benzotriazole) and UV sta-bilizers (e.g., hindered amines). Hydroxybenzotria-zoles preferentially absorb light in the 300–400 nmwavelength range. They dissipate the light energyby a tautomeric process, which protects the polymerby preventing it from absorbing harmful radiation.Hindered amines, on the other hand, act as radi-cal scavengers. Through the formation of nitroxylradicals, hindered amines terminate and deactivatealkyl radicals and peroxy radicals, which are knownto participate in the photo-oxidation process. Whilefunctioning as radical scavengers, the stabilizingspecies (the nitroxyl radical) is regenerated andcontinues to scavenge.[7]

Antioxidants are also commonly used to aid inUV stabilization. Although antioxidants are neitherlight stabilizers nor UV absorbers, they oftenimprove the overall weatherability of the TPUwhen used in combination with a UV absorber or

light stabilizer. They do this by interrupting thefree-radical process during photo-oxidation.[7]

It is also very common to color the resin blackand add components for UV stabilization.

Yellowness and change in physical properties forPellethane® 2103-80AEF resins were measured afterexposure to QUV light. UV stabilizers, both a benzo-triazole and a hindered amine, were added at a UVstabilizer level of 0.25% and 0.5%, respectively. Theaddition of the UV stabilizers does reduce the rateand extent of yellowing in Pellethane® 2103-80AEFresins. Despite the color development, Pellethane®

2103-80 AEF resins maintain physical strength toa considerable extent after QUV exposure. With nostabilizer, there is about 30% loss of tensile strengthand elongation after 2000 hours of exposure. Withstabilizers, the loss is less than 10%. In anotherQUV study it was found that neither a UV absorbernor a light stabilizer alone was sufficient to retarddiscoloration and retain good physical properties.However, synergism did occur when the two wereblended together and used as a package.[7]

66: Urethane Thermoplastic Elastomer 317

Weathering Properties by Material Supplier Trade Name

Table 66-1. Properties Retained after Fadeometer Accelerated Weathering for Noveon Estane® 58202and Estane® 58300 Urethane Thermoplastic Elastomer

318 The Effects of UV Light and Weather on Plastics and Elastomers

Table 66-2. Properties Retained after Fadeometer and QUV Accelerated Weathering for Noveon Estane®

58315 Urethane Thermoplastic Elastomer

66: Urethane Thermoplastic Elastomer 319

Table 66-3. Properties Retained after Fadeometer Accelerated Weathering for Noveon Estane® 58315and Estane® 58863 Urethane Thermoplastic Elastomer

320 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 66-1. Elongation after QUV Exposure of Dow Pellethane® 2103-80 AEF Urethane ThermoplasticElastomer.

Graph 66-2. Tensile Strength after QUV Exposure of Dow Pellethane® 2103-80 AEF Urethane ThermoplasticElastomer.

66: Urethane Thermoplastic Elastomer 321

Graph 66-3. Yellowness Index after QUV Exposure of Dow Pellethane® 2103-80 AEF Urethane ThermoplasticElastomer.

Graph 66-4. Yellowness Index after QUV Exposure of BASF Elastollan® 1185A-10 Urethane ThermoplasticElastomer.

322 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 66-5. Tensile Strength after Xenon Weatherometer Exposure of BASF Elastollan® 1185A-10 UrethaneThermoplastic Elastomer.

Chapter 67

Nitrile Thermoplastic Elastomers

Category: Elastomer, TPE, thermoplastic.

General Properties: Eliokem Chemigum® NBRelastomers are copolymers of acrylonitrile and buta-diene. They are used as elastomeric modifiers,especially in PVC.[193]

Weathering Properties

Chemigum® displays excellent resistance to out-door weathering. After two years of exposure inFlorida, both direct and under glass, Chemigum didnot exhibit severe chalking, exudation, cracks, orunsightly blemishes on the surface.[194]

324 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 67-1. Material Properties after Florida Outdoor Weathering of Eliokem Chemigum® NitrileThermoplastic Elastomer

Chapter 68

Thermoset Elastomers or Rubbers:Overview

Acrylic Rubber: An alkyl-acrylate copolymer thathas good resistance to oxygen at normal and ele-vated temperatures, excellent ozone and weatheringresistance, but poor moist heat resistance.[195]

Butyl: Butyl was originally known as “the inner tuberubber.” Butyl is resistant to ozone and weathering.

Chlorosulfonyl Polyethylene has excellent resis-tance to oxygen and ozone.[195]

Ethylene-Propylene Copolymer is similar tostyrene-butadiene rubber (SBR) but demonstratesimproved resistance to atmospheric aging, oxidiza-tion, and ozone.[195]

EPDM: The polymer of ethylene-propylene dienemonomer is an ethylene-propylene terpolymer syn-thetic rubber that exhibits outstanding resistance toweathering, aging, ozone, and oxygen.[200]

Fluorocarbon Elastomer: Fluorocarbons are theend product of the copolymerization of highly flu-orinated olefins. Fluorocarbons are resistant to theeffects of ozone, oxygen, and sunlight.

Natural Rubber: This is nature’s main “ready-made” contribution to the field of elastomers.

Its chief source is the Hevea brasiliensis, a commer-cially grown tree found principally in the Far East.Natural rubber does not age as well as many of thesynthetics, and is inferior to the synthetic elastomersin its resistance to sunlight, oxygen, and ozone.

Neoprene: Neoprene, chloroprene rubber, is a poly-mer of chloroprene and has several properties that aresuperior to natural rubber, including better resistanceto sunlight, ozone, and oxidation.[196]

Silicone Rubber: Silicone rubber is one of the ver-satile families of semi-organic synthetics known assilicones that look and feel like organic rubber, yethave a completely different type of structure thanother elastomers. The backbone of the elastomer isnot a chain of carbon atoms but an arrangementof silicon and oxygen atoms. Silicone elastomersshow no molecular orientation or crystallizationon stretching and must be strengthened usingreinforcing materials. Silicone elastomers are resis-tant to oxygen and ozone, even at elevatedtemperatures.[196]

SBR is a synthetic copolymer of styrene and buta-diene. SBR provides good resistance to sunlight andozone.

326 The Effects of UV Light and Weather on Plastics and Elastomers

Table 68-1. Comparison of Ozone Resistance and Weather Resistance for a Few ThermosetElastomers[197]

Material Ozone Resistance Weather Resistance

Nitrile Poor Fair

SBR Poor Fair

Neoprene Good/excellent Excellent

Ethylene Propylene Excellent Excellent

Fluorocarbon Excellent Excellent

Fluorosilicone Excellent Excellent

Polyacrylate Excellent Excellent

Polyurethane Excellent Excellent

Silicone Excellent Excellent

Chapter 69

Butyl Rubber, Bromobutyl Rubber, andChlorobutyl Rubber

Category: Thermoset, rubber.

General Properties: Butyl rubber is a copolymerof isoprene (minor) and isobutylene. Exxon bromo-butyl (BIIR), a brominated copolymer of isobuty-lene and isoprene, has a predominantly saturatedbackbone of butyl. Exxon chlorobutyl (CIIR), achlorinated copolymer of isobutylene and isoprene,is an elastomeric isobutylene-isoprene copolymer(halogenated butyl) containing reactive chlorine.Chlorobutyl and bromobutyl contain 1.2% of thehalogenated butyl. The halogen addition changes thecure characteristics and can improve adhesion.[198]

Weathering Properties

Butyl, bromobutyl, and chlorobutyl are resistantto aging, ozone, and weathering from atmosphericexposure.[198]

Carbon black-filled bromobutyl compoundshave high resistance to weathering. Light-coloredcompounds should be formulated to minimize degra-dation to UV light. The following techniques aresuggested for maximum weather resistance inmineral-filler compounds.[199]

1. Obtain a high state of cure.

2. Use low levels of a high quality paraf-finic plasticizer.

3. Include UV light absorbers such astitanium dioxide.

4. Depending upon the application, useup to 10 phr of paraffin wax to protectthe surface.

5. Avoid clays, to the extent possible,especially hard clays. Calcium car-bonates, talcs, and silicas generallyperform better.

Isobutylene backbone polymers are generallysusceptible to attack by UV radiation. In light-colored compounds, this results in chain scissionand the development of surface tack with high dirtretention. Carbon black-filled isobutylene polymercompounds have good weathering resistance to UVattack and weathering, in general, due to the maskingand UV absorption effects of carbon black.[200]

Weathering Properties:Ozone Resistance

The low level of chemical unsaturation in thebutyl polymer chain produces an elastomer withgreatly improved resistance to ozone when com-pared to polydiene rubbers (such as polybutadiene,polyisoprene, and styrene-butadiene rubbers). Butyl,with the lowest level of unsaturation, provides highlevels of ozone resistance, which is also influ-enced by the type and concentration of vulcanizatecross-links. For maximum ozone resistance, as inelectrical insulation, the least unsaturated butyl isadvantageously used.[201]

Bromobutyl shows good resistance to attack byozone due to its high saturation. It is superior togeneral-purpose rubbers. High loadings of fillersand plasticizers are detrimental to ozone resistance,especially highly aromatic oils even at moderatelevels.Amine, resin, thiourea, and alkylphenol disul-fide cures of bromobutyl yield vulcanizates with highozone resistance.[199]

Chapter 70

Chlorosulfonated Polyethylene Rubber

Category: Elastomer, thermoset.

General Properties: DuPont Elastomers Hypalon®

chlorosulfonated polyethylene resists the damagingeffects of weather, including UV and ozone.[98]

• Hypalon® 20: 29% chlorine content,1.4% sulfur content

• Hypalon® 30: 43% chlorine content,1.1% sulfur content

• Hypalon® 40: 35% chlorine content,1% sulfur content

• Hypalon® 45: 24% chlorine content,1% sulfur content

Weathering Properties

Vulcanizates of this chlorosulfonated polyethy-lene synthetic rubber are highly resistant to ozone,oxygen, weather, heat, oil, and chemicals. Hypalonresists discoloration on exposure to light and iswidely used in light-colored vulcanizates.[98]

Hypalon® 40 is the most weather resistant type,and although the differences are small, they areenough to suggest that Hypalon® 40 can be used foroutdoor applications where possible.[202]

Ten-year test results on vulcanizates ofHypalon® 48 indicate that it sheds dirt better thanHypalon® 40.[202]

Hypalon® 20 dissolves in solvents to give muchlower solution viscosities (or higher solid content atequivalent viscosity) thus making it suitable for thepreparation of weather resistant flexible films fromsolution. Hypalon® 30 offers low solution viscositiesbut is a much stiffer material.[202]

Hypalon® 45, a more crystalline material, hassufficient strength to be used in the uncured state.Uncured compounds of Hypalon® 45 may actuallybenefit from exposure to the weather as a result of

gradual cross-linking promoted by UV exposure andmoisture. Long-term exposure data demonstratesthat, when properly compounded, Hypalon® 45 hasexcellent weathering resistance.[202]

Weathering Properties:Color Pigments

The type and amount of pigments are criti-cal because Hypalon® requires protection from UVlight. Unpigmented compounds of Hypalon® darkenand craze after six to twelve months of directexposure to sunlight.[202]

It is desirable to select only those color pigmentsthat show a high degree of opacity to UV radiation.This restricts the penetration of UV radiation andthe subsequent deterioration of the outermost surfacewhere it is observed mainly as a loss of gloss ratherthan crazing. In addition, a pigment that protects thesurface of a compound of Hypalon® from deteriora-tion during outdoor exposure is of little value unlessit also maintains its color.[202]

The retention of color by vulcanizates ofHypalon® after exposure to weather varies consider-ably with the pigment used since all color pigmentsdo not afford the same degree of color stability. It isimportant to remember that pigments differ in theircolor stability and opacity. Yellows and oranges arelower in tinctorial strength and durability than bluesand greens. These differences are usually accentu-ated in pastels where orange and yellow fade muchmore rapidly than blue or green when used at thesame ratio of color to titanium dioxide. Blends ofcolor pigment and titanium dioxide are frequentlyused for purposes of economy and/or color match.Although adequate in mass tones, orange and yellowshould not be used in very light tints where colorstability is important.[202]

A study was conducted on pigments specificallyrecommended for use in compounds of Hypalon®.

330 The Effects of UV Light and Weather on Plastics and Elastomers

Table 70-1. Color Pigments Recommended for Use in Hypalon® [202]

The recommended pigments were divided into fourgroups ranging from the most to the least efficient ona weight basis. The most efficient were those wherethe minimum suggested amount is 3 phr of Hypalon®.Compounds containing three parts have not crazedafter ten years of exposure to direct sunlight inDelaware. The next group—mass tones of orangeand yellow—is somewhat less efficient, requiring 6phr. They have been exposed to direct Delaware sun-light for fifteen years without objectionable colorchange or crazing; but pastels of these colors aremuch less permanent. The third group consists ofred iron oxide. Iron oxide is very stable but is lessbrilliant than organic pigments. Because of its low

tinctorial strength the minimum suggested amount is10 phr. The last group contains titanium oxide, whichis the only pigment satisfactory for use in Hypalon®.The most chalk-resistant rutile grades should beused unless a self-cleaning surface is desired; thesuggested minimum is 35 phr.[202]

Weathering Properties:Curing Systems

In nonblack stocks, magnesia/pentaerythritol ispreferred except when maximum water resistance

70: Chlorosulfonated Polyethylene Rubber 331

is required. In such a case, tribasic lead maleate is sat-isfactory. If flexibility is important, no more than fiveparts of magnesia should be used. Vulcanizates con-taining high amounts of magnesia stiffen on exposureto weather. In black stocks, a litharge curing systemis the most satisfactory.[202]

The choice of curing systems depends primarilyupon the requirements for color and water resistance.There are four curing systems from which to choose:magnesia, magnesia/pentaerythritol, litharge, andtribasic lead maleate. Compounds designated to beused uncured can be formulated using Hypalon® 45as the base polymer.[202]

Nonblack (Colored) Compounds: If maximumwater resistance is not required, the compound maybe cured with magnesia alone or with a magne-sia/pentaerythritol combination. Compounds curedwith either system have excellent colorability, andthey retain their color and smooth surface duringoutdoor exposure. Of the two systems, the magne-sia/pentaerythritol system is generally more useful.Compounds cured with twenty parts of magne-sia have better abrasion resistance and retain colorslightly better, but they are sometimes scorchy andstiffen noticeably upon exposure to weather. (If flex-ibility is important, magnesia content should notexceed five parts.) Compounds cured with magne-sia/pentaerythritol generally exhibit greater process-ing safety and retain their flexibility on exposure toweather. Their color retention, if not quite the equalof an all magnesia-cured compound, is neverthelessexcellent.[202]

Litharge is the recommended curing agent. Itis necessary if low water swell is required and ispreferred even if water resistance is not required.Litharge-cured compounds are safe processing andhave good physical properties. After fifteen-yearexposure tests they show trace crazing and still retainflexibility.[202]

The magnesia/pentaerythritol combination maybe used if a black, lead-free compound is requiredwithout maximum water resistance. Compoundscured with magnesia/pentaerythritol are resistant tocrazing and they retain their strength and flexibilitywhen aged outdoors.[202]

Hypalon® compounds retain much of their elon-gation during exposure to weather. It is also observedthat the rate of elongation loss decreases with

time—most loss occurs in lightly loaded compounds.Compounds containing higher levels of black aremore stable.[202]

Weathering Properties: Fillers

Calcium carbonate is preferred as it chalks lessthan other fillers.[202]

Several types of fillers are suitable for use inHypalon®. Whiting is preferred from the viewpointof weatherability alone; however, in many cases itis necessary to use other extenders for specific pro-perties (e.g., water resistance) not obtainable withwhiting. A summary of the performance of severalcommonly used fillers is given below.[202]

Whiting (Calcium Carbonate): Vulcanizates con-taining 50 parts show trace crazing and moderatechalking after ten years of direct sun exposure inDelaware. White vulcanizates containing 200 partshave been exposed for eighteen months in Floridawithout surface deterioration. After fifteen years,mass tone green vulcanizates containing 150 partswhiting begin to chalk slightly and show trace craz-ing. Fine particle size precipitated calcium carbonateis entirely suitable for use in Hypalon® and oftengives better physical properties. Since Hypalon® isnot entirely dependent on pigment reinforcement,economic factors usually favor the use of groundwhiting.[202]

Clay (Aluminum Silicate): Yellow vulcanizatescontaining fifty parts of clay have shown excellentweather resistance.[202]

Talc (Magnesium Silicate): Fading and chalkingincrease with increasing amounts of talc in coloredcompounds. Approximately 50 phr would be themaximum loading in white or light colors and 75phr in black compounds.[202]

Silica (Silicon Dioxide): Silica is not suggested as aprimary filler as silica-filled vulcanizates have shownvisible crazing after only one year in Florida.[202]

332 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties:Plasticizers

Plasticizers have little influence on the crazeresistance of vulcanizates of Hypalon® when usedin moderate amounts (5–25 parts). No data are avail-able on the durability of more highly plasticizedformulations.[202]

Weathering Properties by Material Supplier Trade Name

Table 70-2. Material Properties Retained and Color Change after Outdoor Weathering and AcceleratedWeathering of DuPont Elastomers Hypalon® Chlorosulfonated Polyethylene Rubber

Plasticizers have an influence on color stability.Aromatic and naphthenic oils discolor and shouldbe avoided in light-colored stocks. Esters and chlo-rinated hydrocarbons show excellent color stabi-lity. Paraffinic oils are very stable, but their loworder of compatibility with Hypalon® limits theirusefulness.[202]

70: Chlorosulfonated Polyethylene Rubber 333

Table 70-3. Material Properties Retained and Color Change after Arizona OutdoorWeathering for DuPontElastomers Hypalon® 40 Chlorosulfonated Polyethylene Rubber

334 The Effects of UV Light and Weather on Plastics and Elastomers

Table 70-4. Material Properties Retained and Color Change after Florida and Delaware Outdoor Weath-ering for Wire Cable Compound DuPont Elastomers Hypalon® 40 Chlorosulfonated PolyethyleneRubber

70: Chlorosulfonated Polyethylene Rubber 335

Table 70-5. Surface and Appearance and Mildew Resistance after Texas and California Outdoor Weath-ering for Green Hose Cover Compound DuPont Elastomers Hypalon® 40 Chlorosulfonated PolyethyleneRubber

336 The Effects of UV Light and Weather on Plastics and Elastomers

Table 70-6. Material Properties Retained and Surface and Appearance after Florida Outdoor Weatheringfor White DuPont Elastomers Hypalon® 40 Chlorosulfonated Polyethylene Rubber

70: Chlorosulfonated Polyethylene Rubber 337

Table 70-7. Material Properties Retained and Surface and Appearance after Delaware Outdoor Weath-ering for DuPont Elastomers Hypalon® 20 Chlorosulfonated Polyethylene Rubber

338 The Effects of UV Light and Weather on Plastics and Elastomers

Table 70-8. Material Properties Retained and Surface and Appearance after Panama OutdoorWeatheringfor Pond Liner Formulation DuPont Elastomers Hypalon® 45 Chlorosulfonated Polyethylene Rubber

70: Chlorosulfonated Polyethylene Rubber 339

Table 70-9. Material Properties Retained and Color Change after EMMA and EMMAQUA AcceleratedOutdoor Weathering for Black DuPont Elastomers Hypalon® 40 Chlorosulfonated Polyethylene Rubber

340 The Effects of UV Light and Weather on Plastics and Elastomers

Table 70-10. Material Properties Retained and Color Change after Xenon Arc Weatherometer Exposurefor Black DuPont Elastomers Hypalon® 40 Chlorosulfonated Polyethylene Rubber

70: Chlorosulfonated Polyethylene Rubber 341

Graph 70-1. Elongation at Break after Delaware Outdoor Exposure for DuPont Elastomers Hypalon® 20Chlorosulfonated Polyethylene Rubber.

Chapter 71

Ethylene-Propylene Copolymer

Category: Elastomer, thermoset.

General Properties: Also known as ethylene-propylene rubber, or ethylene-propylene elas-tomer, Polimeri Dutral® is an ethylene-propylenecopolymer.[205]

Weathering Properties

All ethylene-propylene elastomers are sensitiveto light and UV rays. If the vulcanized part is black,

Weathering Properties by Material Supplier Trade Name

Graph 71-1. Carbonyl Formation after Xenon Arc Exposure for Ethylene-Propylene Copolymer.

the carbon black it contains acts as an absorber,protecting items exposed to atmospheric agents andlight for decades.[206]

In the case of light-colored vulcanized items, itis advisable to attenuate the phenomenon with:[206]

1. high molecular weight Dutral®

2. high purity paraffinic oils

3. zinc oxide, 15–20 phr

4. rutile titanium dioxide

5. phthalocyanine-based pigments

344 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 71-2. Decrease in Molecular Weight after Xenon Arc Exposure for Ethylene-Propylene Copolymer.

Chapter 72

Ethylene-Propylene Diene MethyleneTerpolymer

UV Resistance

Ausimont Dutral-TER: All ethylene-propyleneelastomers are sensitive to light and UV rays. If thevulcanized part is black, the carbon black it con-tains acts as an absorber, protecting items exposedto atmospheric agents and light for decades.

In the case of light-colored vulcanized items, itis advisable to attenuate the phenomenon with:

1. high molecular weight Dutral

2. high purity paraffinic oils

3. zinc oxide, 15–20 phr

4. rutile titanium dioxide

5. phthalocyanine-based pigments

The various UV stabilizers currently usedwith plastomeric polymers are not particularlyeffective.[206]

Outdoor Weather Resistance

DuPont Nordel: Nordel hydrocarbon rubber canbe compounded to give economical, highly weatherresistant vulcanizates.After twenty years of continu-ous outdoor exposure in Florida (45◦ south), properlycompounded mineral-filled vulcanizates show slightchecking and moderate chalking with an erosionrate of about 0.5 mil/year. After twenty years inFlorida (45◦ south), general purpose black-loadedcompounds retain good elastomeric properties, showsome chalking but with erosion rates of less than0.05 mil/year. Slight surface checking is visible at10× magnification.

Maximum weather resistance can be obtainedby using one or more of the following compoundingtechniques:

1. Adding pigments or fillers that giveprotection against UV light.

2. Using process oils that have a lowaromaticity.

3. Adding zinc oxide beyond the recom-mended limit for curing.

4. Incorporating an antioxidant.

Special Compounding when the Vulcanizate isWeathered with a Static or Dynamic Strain:General-purpose black vulcanizates from ethylene-propylene diene methylene (EPDM), while exhibit-ing outstanding weather resistance under normalexposure conditions, may show accelerated devel-opment of surface crazing if they are exposedwhile subject to a continuous static or dynamicstrain. Surface crazing of Nordel hydrocarbon rubbervulcanizates, under these conditions, can be mini-mized by:

• Using a fine particle size black (e.g.,HAF black).

• Using a process oil with a low levelof aromaticity (preferably less than 1%aromatics).

• Using ca. 1 phr of an antioxidant.Neozone D is best, but a hinderedbis-phenol antioxidant should be usedif staining is a problem.

Special Compounding for Tensile StrengthRetention: Mineral-filled vulcanizates from Nordelhydrocarbon rubber, like those from most other elas-tomers, tend to lose tensile strength when exposed to

346 The Effects of UV Light and Weather on Plastics and Elastomers

natural weathering. This loss can either be markedlyreduced by compounding with 5 phr of Hypalon45 synthetic rubber or completely eliminated byheat treating the stock with quinone dioxime.Quinone dioxime causes marked discolorationduring cure, which limits its use to dark-coloredvulcanizates.[207]

Exxon Vistalon 5600 (features: black color, 76Shore A hardness; material composition: 100 phrVistalon 5600, 100 phr N-550 carbon black,100 phr N-774 black, 100 phr naphthenic processoil, 5 phr zinc oxide, 2 phr stearic acid, 1 phrFlectol H (Monsanto), 2 phr sulfur, 1.5 phr Thiotax(Monsanto), 0.8 phrTDEDC, 0.8 phr DPTTS, 0.8 phrThiurad (Monsanto)): EPDM was exposed to con-ventional Arizona aging by DSET Laboratories, Inc.(Phoenix, AZ) at a 5◦ tilt from the horizontal. Thistilt is preferable to 0◦ as it allows for some drainageand dirt wash off during rains. Direct exposuresare intended for materials that are to be used out-doors and subjected to all elements of weather. Theexposure periods were 6, 12, 24, and 48 months.EPDM shows a color change (�E) of less than 3during the total aging cycle. Over the 48-monthperiod EPDM experienced a significant increasein hardness and maintained reasonably good ten-sile strength. Although EPDM retained its tensilestrength, its ability to be elongated decreased withexposure time.

EPDM was also exposed to conventionalArizona aging with spray. This exposure methodis the same as conventional aging, except that awater spray is used to induce moisture weatheringconditions. The introduction of moisture plays animportant role in improving both the relevancy andthe reproducibility of the weathering test results.Spray nozzles are mounted above the face of therack at points that are distributed so as to ensureuniform wetting of the entire exposure area. Dis-tilled water is sprayed for four hours precedingsunrise to soak the samples, and then twenty timesduring the day in 15-second bursts. The purposeof the wetting is twofold. First, the introductionof water in the otherwise arid climate inducesand accelerates some degradation modes that donot occur as rapidly, if at all, without moisture.Second, a thermal shock causes a reduction in

specimen surface temperatures as much as 14◦C(25◦F). This results in physical stresses that accel-erate the degradation process. EPDM discoloredwithin six months and continued to increase in �Ewith exposure. The hardness of EPDM increasessignificantly with exposure time. Although EPDMmaintained its tensile strength during the exposureperiod, its elongation decreased significantly withexposure.

EPDM was also exposed to conventional Floridaaging. This test method is a real-time exposure byDSET Laboratories, Inc. (Homestead, FL) at a 5◦ tiltfrom the horizontal. Since this location has a muchhigher average humidity, this exposure is harsher onsome materials. Testing on EPDM was not accom-plished over the total exposure period. Samples at 48months had deteriorated past the point of meaning-ful testing. The data show significant color changewith exposure time. The material sustained its tensilestrength with exposure.

Conventional Florida aging with spray was usedto test EPDM. This exposure method is the same asconventional aging, except that a water spray is usedto induce moisture weathering conditions. Moistureis introduced in the same manner as in Arizona.EPDM showed significant color and hardness chan-ges during the 48 months of exposure, butretained good tensile strength. The specimens hada continuing decrease in elongation with exposuretime.[208]

EPDM (features: weatherable, black color, 65 ShoreA hardness, 3.2 mm thick; manufacturing method:compression molding): EPDM rubber does notweather well when exposed under glass. The sur-face was covered with mildew like growth. Unsightlyblemishes remained visible even after washing.[194]

Accelerated Outdoor WeatheringResistance

Exxon Vistalon 5600: Outdoor accelerated expo-sure testing was done using equatorial mount withmirrors for acceleration (EMMA) on EPDM. Thistest method uses natural sunlight and special reflect-ing mirrors to concentrate the sunlight to the intensity

72: Ethylene-Propylene Diene Methylene Terpolymer 347

of about eight suns. A blower directs air over andunder the samples to cool the specimens. This limitsthe increase in surface temperatures of most mate-rials to 10◦C (18◦F) above the maximum surfacetemperature that is reached by identically mountedsamples exposed to direct sunlight at the same timeand locations without concentration. DSET Labora-tories designed and maintains this equipment. Theexposure period was a total of 6 and 12 months,which has been correlated to about 2.5 and 5 yearsof actual aging in a Florida environment, respec-tively. While EPDM retained its tensile strength,it showed a significant increase in hardness anda significant deterioration in elongation during theexposure period.

Specimens were also exposed to an equato-rial mount with mirrors for acceleration plus water(EMMAQUA). This is an accelerated weatheringtest method which uses the same apparatus asEMMA, except that a water spray is used to inducemoisture weathering conditions. EPDM showed amajor change in color and hardness along with sig-nificant decreases in elongation and tensile strengthwith exposure time.[208]

Accelerated Artificial WeatheringResistance

Exxon Vistalon 5600: Under xenon arc weathero-meter testing (as per General Motors standardTM30-2 and SAE J1885) EPDM displays a significantchange in both color and hardness with exposure.Retention of tensile strength is good. However,elongation retention is poor.[208]

Effect of Carbon Black onWeatherability

DuPont Nordel 1070 (cure: 20 minutes @ 160◦C;features: black color; material composition: 100 phrNordel 1070, 1 phr stearic acid, 5 phr zinc oxide,80 phr paraffinic oil, 1.5 phr zinc dimethyl dithio-carbonate, 1.5 phr tetramethyl thiuram disulfide,1 phr zinc mercatobenzothiazole, 2 phr sulfur, 80 phr

FEF carbon black), Nordel: Vulcanizates of Nordelhydrocarbon rubber have outstanding weather resis-tance when they contain at least 5 phr of a furnaceblack. In practical black-loaded vulcanizates, theconcentrations of black and oil have no significantbearing on weather resistance within the ranges of20–150 parts of black and 20–100 parts of oil. Forexample, weathering produces no more change ina vulcanizate loaded with 150 phr of black and100 phr of oil than in one containing only 20 phrof each. Low concentrations (e.g., 5 phr) of fur-nace black provide very good weather protection inmineral-filled vulcanizates; compounds of this typeare of particular interest in coverings for wires andcables.[207]

Effect of Color Pigments onWeatherability

DuPont Nordel 1070 (cure: 20 minutes @ 160◦C;features: white color; material composition: 100 phrNordel 1070, 1 phr stearic acid, 20 phr zinc oxide,80 phr hard clay, 80 phr paraffinic oil, 1.5 phr zincdimethyl dithiocarbonate, 1.5 phr tetramethyl thi-uram disulfide, 1 phr zinc mercaptobenzothiazole,2 phr sulfur, 1 phr phenolic antioxidant, 35 phrTi-Pure R-610 (replaced by Ti-Pure R-960), Nordel:All nonblack vulcanizates should contain titaniumdioxide and/or opaque colored pigments since con-ventional mineral fillers, by themselves, providelittle protection against UV radiation. Combinationsof titanium dioxide and colored pigments can be usedto produce weather resistant vulcanizates with brightcolors or pastel shades.

The table that follows lists proportions of indi-vidual pigments and pigment blends that provideoptimum protection for mineral-filled vulcanizatesof Nordel hydrocarbon rubber.

Mineral-filled vulcanizates show better weatherresistance at low to medium oil and filler loadingsthan at high extensions. Highly loaded vulcanizates(e.g., those containing 60 volumes of Nordel) tend todevelop a brittle surface layer on weathering, causingfine cracks to appear on the surface if the vulcan-izate is stretched or bent. This is not apparent whenmoderate loading levels are used, such as 30 volumesof filler per hundred volumes of Nordel.[207]

348 The Effects of UV Light and Weather on Plastics and Elastomers

Effective UV Screening Agents in Mineral-Filled Vulcanizates

Suggested Combination ofMinimum Amount of Pigment and Titanium

Pigment Alone, Needed Dioxide for Bright Color andPigment for Good UV Screening Good Weathering (phr)

(phr)Titanium DioxidePigment

Furnace Black 5

Ti-Pure R-960 (DuPont) 25

Phthalocyanine Green 5* 2 20

Chrome Green 9

Phthalocyanine Blue 8* 1 25

Chrome Yellow 9 5 to 10 20

Iron Oxide (Yellow or Red) 10 20

Quinacridone Red 8* 2

Pyrazalone Red 8

Note: Chrome yellow fades with clay loading. Super-Multiflex loading gives better color stability. With Super-Multiflexloading, 5 phr Hypalon 45 in the compound enhances physical properties. Pyrazalone Red gives a bright red color, butthis fades with a clay loading. Super-Multiflex gives better color stability. This pigment can stain painted surfaces bymigration from the vulcanizate.*Amount shown gives very dark colors.

Effect of Curing Systems onWeatherability

DuPont Nordel: Good weather resistance can beobtained with sulfur or peroxide cures.[207]

Effect of Plasticizers onWeatherability

DuPont Nordel 1070, Nordel: Vulcanizates ofNordel containing at least 20 phr of a reinforc-ing carbon black are so weather resistant that inmost applications the type of oil used is unimpor-tant. Differences between oils do become signifi-cant, however, with very long (e.g., 20 years)outdoor exposure, or if outdoor exposure involvesflexing or static strain of 20% or more; in such cases,

naphthenic or paraffinic oils having a minimum aro-matic content should be used, and 5% aromaticcarbon atoms should be considered a maximum forthese exposure conditions.

Process oils with a minimum aromatic con-tent should be used in all mineral-filled compoundsfor best weather resistance as well as good colorstability during cure and weathering. If good colorstability is essential, the oil—whether paraffinicor naphthenic—should be selected on the basis ofminimum aromatic content.[207]

Ozone Resistance

Exxon Vistalon 5600: The results of both ASTMD1171 and ASTM D518 ozone testing indicatethat EPDM rubber exhibits outstanding resistanceto ozone.[176]

72: Ethylene-Propylene Diene Methylene Terpolymer 349

Table 72-1. Mechanical Properties Retained after Outdoor and Accelerated Outdoor Weathering ofWhite, Randomly Selected, Unstrained EPDM Terpolymer

350 The Effects of UV Light and Weather on Plastics and Elastomers

Table 72-2. Mechanical Properties Retained after Outdoor and Accelerated OutdoorWeathering of Black,Weather Resistant, Unstrained EPDM Terpolymer

72: Ethylene-Propylene Diene Methylene Terpolymer 351

Table 72-3. Mechanical Properties Retained after Outdoor and Accelerated OutdoorWeathering of Black,Randomly Selected, Unstrained EPDM Terpolymer

352 The Effects of UV Light and Weather on Plastics and Elastomers

Table 72-4. Mechanical Properties Retained and Color Change after Outdoor Weathering, AcceleratedOutdoor Weathering by EMMAQUA, and Accelerated Weathering with a Xenon Arc Weatherometer forBlack Exxon Vistalon EPDM Terpolymer

72: Ethylene-Propylene Diene Methylene Terpolymer 353

Table 72-5. Material Properties Retained and Color Change after Arizona Outdoor Weathering With andWithout Water Spray Added for Black Exxon Vistalon 5600 EPDM Terpolymer

354 The Effects of UV Light and Weather on Plastics and Elastomers

Table 72-6. Mechanical Properties Retained and Color Change after Arizona Outdoor Weathering ofBlack Exxon Vistalon 5600 EPDM Terpolymer

72: Ethylene-Propylene Diene Methylene Terpolymer 355

Table 72-7. Mechanical Properties Retained after Florida Outdoor Weathering and Accelerated OutdoorWeathering by EMMA for Black, Weather Resistant, Strained EPDM Terpolymer

356 The Effects of UV Light and Weather on Plastics and Elastomers

Table 72-8. Material Properties Retained and Color Change after Florida Outdoor Weathering With andWithout Water Spray Added for Black Exxon Vistalon 5600 EPDM Terpolymer

72: Ethylene-Propylene Diene Methylene Terpolymer 357

Table 72-9. Material Properties Retained and Surface and Appearance after Florida Outdoor Weatheringof Weatherable EPDM Terpolymer

358 The Effects of UV Light and Weather on Plastics and Elastomers

Table 72-10. Mechanical Properties Retained after Florida OutdoorWeathering and Accelerated OutdoorWeathering by EMMA for Black, Randomly Selected, Strained EPDM Terpolymer

72: Ethylene-Propylene Diene Methylene Terpolymer 359

Table 72-11. Mechanical Properties Retained after Florida OutdoorWeathering and Accelerated OutdoorWeathering by EMMA for White, Randomly Selected, Strained EPDM Terpolymer

360 The Effects of UV Light and Weather on Plastics and Elastomers

Table 72-12. Material Properties Retained and Color Change after Florida Outdoor Weathering of BlackEPDM Terpolymer

72: Ethylene-Propylene Diene Methylene Terpolymer 361

Table 72-13. Material Properties Retained and Color Change after Accelerated Outdoor Weathering byEMMA and EMMAQUA and Accelerated Weathering in a Xenon Arc Weatherometer for Black ExxonVistalon 5600 EPDM Terpolymer

362 The Effects of UV Light and Weather on Plastics and Elastomers

Table 72-14. Mechanical Properties Retained and Color Change after Arizona Accelerated OutdoorWeathering by EMMA and EMMAQUA for Black Exxon Vistalon 5600 EPDM Terpolymer

72: Ethylene-Propylene Diene Methylene Terpolymer 363

Table 72-15. Mechanical Properties Retained after Accelerated Weathering in a UV-CON and a XenonArc Weatherometer for White, Randomly Selected, Strained EPDM Terpolymer

364 The Effects of UV Light and Weather on Plastics and Elastomers

Table 72-16. Mechanical Properties Retained after Accelerated Weathering in a UV-CON and a XenonArc Weatherometer for White, Randomly Selected, Unstrained EPDM Terpolymer

72: Ethylene-Propylene Diene Methylene Terpolymer 365

Table 72-17. Mechanical Properties Retained after Accelerated Weathering in a UV-CON and a XenonArc Weatherometer for Black, Weather Resistant, Strained EPDM Terpolymer

366 The Effects of UV Light and Weather on Plastics and Elastomers

Table 72-18. Mechanical Properties Retained after Accelerated Weathering in a UV-CON and a XenonArc Weatherometer for Black, Randomly Selected, Unstrained EPDM Terpolymer

72: Ethylene-Propylene Diene Methylene Terpolymer 367

Table 72-19. Mechanical Properties Retained and Color Change after AcceleratedWeathering in a XenonArc Weatherometer of Black Exxon Vistalon 5600 EPDM Terpolymer

368 The Effects of UV Light and Weather on Plastics and Elastomers

Table 72-20. Mechanical Properties Retained after Accelerated Weathering in a UV-CON and a XenonArc Weatherometer for Black, Weather Resistant, Unstrained EPDM Terpolymer

72: Ethylene-Propylene Diene Methylene Terpolymer 369

Table 72-21. Mechanical Properties Retained after Accelerated Weathering in a UV-CON and a XenonArc Weatherometer of Black, Randomly Selected, Strained EPDM Terpolymer

370 The Effects of UV Light and Weather on Plastics and Elastomers

Table 72-22. Surface and Appearance and Ozone Resistance of Exxon Vistalon EPDM Terpolymer

72: Ethylene-Propylene Diene Methylene Terpolymer 371

Table 72-23. Surface and Appearance and Ozone Resistance of EPDM Terpolymer

372 The Effects of UV Light and Weather on Plastics and Elastomers

Graph 72-1. Carbonyl Formation after Xenon Arc Weatherometer Exposure of EPDM Terpolymer.

Graph 72-2. Decrease in Molecular Weight after Xenon Arc Weatherometer Exposure of EPDM Terpolymer.

Chapter 73

Neoprene Rubber

Category: Elastomer, thermoset.

General Properties: DuPont Elastomers Neoprene®

is composed of polychloroprene. The polymerstructure can be modified by copolymerization withsulfur or 2,3-dichloro-1,3-butadiene to yield a broadrange of chemical and physical properties.

Weathering Properties

All types of neoprene resist degradation from thesun, ozone, and weather, and perform well in contactwith oils and many chemicals.

Chloroprene (black color, 76 Shore A hardness)with the following composition—100 phr NeopreneW, 1 phr stearic acid, 4 phr magnesium oxide,2 phr Flectol ODP, 70 phr N-774 black, 25 phrN-330 black, 25 phr process oil, 5 phr zinc oxide,1 phr sulfur, 0.75 phr monothruad, 0.75 phr DOTG—was exposed to the following weathering tests.

Arizona Aging: Samples were exposed at a 5◦ tiltfrom the horizontal. This tilt is preferable to the flator 5◦ position since it allows for some drainage anddirt to wash off during rains. Direct exposures areintended for materials that will be used outdoors andsubjected to all elements of weather. The exposureperiods were 6, 12, 24, and 48 months. Chloropreneshowed a color change (�E) of less than 3 during thetotal aging cycle. Over the 48-month period chloro-prene experienced a significant increase in hardnessand maintained reasonably good tensile strength.Although chloroprene retained its tensile strength, itsability to be elongated decreased with exposure.[208]

Arizona Aging with Spray: The introduction ofmoisture plays an important role in improving boththe relevance and the reproducibility of the weath-ering test results. The introduction of water in theotherwise arid climate induces and accelerates some

degradation modes that do not occur as rapidly, if atall, without moisture. In addition, a thermal shockcauses a reduction in specimen surface temperaturesas much as 14◦C (61◦F). This results in physi-cal stresses that accelerate the degradation process.Chloroprene discolored within six months and con-tinued to increase in �E with exposure. The hardnessof chloroprene increased significantly while the elon-gation decreased significantly with exposure time.During the exposure period the material maintainedits tensile strength.[208]

Florida Aging: This test method is a real-time expo-sure at a 5◦ tilt from the horizontal. Since this locationhas a much higher average humidity, this exposureis harsher on some materials. Samples at 48 monthshad deteriorated past the point of meaningful testing.The data show significant color change with expo-sure time. Chloroprene showed a major decrease inboth tensile strength and elongation retention almostimmediately after exposure.[208]

Florida Aging with Spray: This outdoor exposuremethod is the same as the conventional aging, exceptthat a water spray is used. Chloroprene showed sig-nificant color, hardness, and tensile strength changesduring the 48 months of exposure. The specimensalso had a continuous decrease in elongation withexposure time.[208]

EMMA: The exposure period was a total of 6 and12 months, which has been correlated to about 2.5and 5 years of actual aging in a Florida environment,respectively. While chloroprene retained its tensilestrength, it showed a significant increase in hardnessand a significant deterioration in elongation duringthe exposure period.[208]

EMMAQUA: This method uses the EMMA set-upwith a water spray to induce moisture weatheringconditions. Chloroprene specimens at 24 months haddeteriorated past the ability to obtain reasonable data.

374 The Effects of UV Light and Weather on Plastics and Elastomers

Prior to that point there were large color changes, sig-nificant loss in tensile strength, and a major decreasein elongation with exposure time.[208]

Xenon Arc: Chloroprene displays a significantchange in both color and hardness with exposure.

Weathering Properties by Material Supplier Trade Name

Table 73-1. Mechanical Properties Retained and Color Change after Arizona Outdoor Weathering andAccelerated Outdoor Weathering by EMMAQUA and Xenon Arc Accelerated Outdoor Weathering forBlack DuPont Neoprene® W Neoprene Rubber

Retention of tensile strength is good, however, reten-tion of color is poor.[208]

Ozone: Under test method ASTM D1171, neoprenecracked within eight hours. Using ASTM D518,neoprene rubber cracked within three hours.[208]

73: Neoprene Rubber 375

Table 73-2. Material Properties Retained, Hardness Change, and Color Change after Arizona and FloridaOutdoor Weathering for Black DuPont Neoprene® W Neoprene Rubber

376 The Effects of UV Light and Weather on Plastics and Elastomers

Table 73-3. Mechanical Properties Retained and Color Change after Arizona Outdoor Weathering andArizona Outdoor Weathering with Spray for Black DuPont Neoprene® W Neoprene Rubber

73: Neoprene Rubber 377

Table 73-4. Material Properties Retained, Hardness Change, and Color Change after Arizona OutdoorWeathering and Arizona Outdoor Weathering with Spray for Black DuPont Neoprene® W NeopreneRubber

378 The Effects of UV Light and Weather on Plastics and Elastomers

Table 73-5. Material Properties Retained, Hardness Change, and Color Change after Florida OutdoorWeathering and Florida Outdoor Weathering with Spray for Black DuPont Neoprene® W NeopreneRubber

73: Neoprene Rubber 379

Table 73-6. Material Properties Retained, Hardness Change, and Color Change after Xenon Arc Accel-erated Weathering and EMMA and EMMAQUA Accelerated Outdoor Weathering for Black DuPontNeoprene® W Neoprene Rubber

380 The Effects of UV Light and Weather on Plastics and Elastomers

Table 73-7. Mechanical Properties Retained and Color Change after EMMA and EMMAQUA ArizonaAccelerated Outdoor Weathering for Black DuPont Neoprene® W Neoprene Rubber

73: Neoprene Rubber 381

Table 73-8. Mechanical Properties Retained and Color Change after Xenon Arc Accelerated Weatheringfor Black DuPont Neoprene® W Neoprene Rubber

382 The Effects of UV Light and Weather on Plastics and Elastomers

Table 73-9. Ozone Resistance after Exposure of Black DuPont Neoprene® W Neoprene Rubber

Chapter 74

Polybutadiene

Category: Elastomer, thermoset.

General Properties: Japanese Synthetic Rubberoffers JSR BR, a low molecular weight, low crys-tallinity syndiotactic 1,2-polybutadiene that has acrystallinity of 15–30%.

Weathering Properties

Polybutadiene, a main component ofacrylonitrile-butadiene-styrene, is susceptible tolight-induced degradation.

384 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 74-1. Ozone Resistance of Japanese Synthetic Rubber JSR BR Polybutadiene Rubber

Chapter 75

Polyisoprene Rubber

Category: Elastomer, thermoset.

General Properties: Polyisoprene rubber is chemi-cally similar to natural rubber. Goodyear Natsyn® isa synthetic cis-polyisoprene.

Weathering Properties

Polyisoprene is susceptible to degradation byweathering.

Like most polymers, Goodyear Natsyn® does notresist degradation due to exposure to UV radiationand ozone unless special compounding techniquesare employed. In a recipe similar to a truck tire treadcompound, two antiozonants are compared aloneand in combination with Sunlite® 240 wax. Agerite®

Resin D at 10 phr is included because it is one wayto provide ozone protection and avoid the stainingcharacteristics of most antiozonants.[211]

In general, the alkyl-aryl p-phenylenediaminesgive the best ozone resistance to Natsyn® and nat-ural compounds. Dialkly p-phenylenediamines arealso effective but less persistent. When a dialkyl p-phenylenediamine is used, a secondary antiozonantwill extend the longevity of protection.[211]

It is often advantageous to use special waxes incombination with the antiozonant. Wax is especially

suitable for static applications because it blooms tothe surface of the compound and becomes a protec-tive coating. However, wax has a significant adverseeffect on ozone resistance in dynamic applicationsand so a good antiozonant is required for maximumprotection.[211]

Polymer blending is another way of improvingthe aging resistance of Natsyn®. Ethylene-propyleneterpolymers (EPDM) are inherently immune toattack by ozone and oxygen and, when properlyblended, are capable of extending this protectionto Natsyn®. In addition, EPDM polymers nei-ther stain nor disappear through volitization. Theseblends are thus suitable for use in light-coloredstocks.[211]

In order to achieve the maximum benefit fromEPDM, proper mixing is essential. Natsyn® breaksdown rapidly in a mill, but EPDM polymers donot. A better dispersion of the two polymers willresult if they have close Mooney viscosities. Expe-rience has shown that ozone resistance is greatlyenhanced if the polymers are well blended beforeother compounding materials are added. Care shouldbe taken to keep the mixing temperature below149◦C in the Banbury to prevent degradation ofNatsyn®. Otherwise normal mixing procedures aresatisfactory.[211]

386 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 75-1. Ozone Resistance of Goodyear Natsyn® 2200 Polyisoprene Rubber as per the Annulus Test

75: Polyisoprene Rubber 387

Table 75-2. Ozone Resistance of Goodyear Natsyn® 2200 Polyisoprene Rubber as per ASTM D1171 LoopOzone Test

388 The Effects of UV Light and Weather on Plastics and Elastomers

Table 75-3. Ozone Resistance of Goodyear Natsyn® 2200 Polyisoprene Rubber as per the StaticStrip Test

75: Polyisoprene Rubber 389

Table 75-4. Ozone Resistance of Goodyear Natsyn® 2200 Polyisoprene Rubber as per the KineticStretch Test

Chapter 76

Polyurethane

Category: Polyurethane.

General Properties: United Coatings Elastuff101/102 is a high solids, moisture-catalyzed, single-component polyurethane coating system.The systemconsists of Elastuff 101, an aromatic polyurethanebasecoat, and Elastuff 102, a UV-resistant, 100%aliphatic polyurethane topcoat.[212]

Weathering Properties

The Elastuff 101/102 system is designed for pro-tecting a wide range of substrates from the effectsof weathering and moisture intrusion. It is par-ticularly effective as a protective membrane overpolyurethane foam on new or existing roofs, and hotor ambient storage tanks. It provides a barrier to theeffects of degradation caused by normal weathering,aging, and UV exposure.[212]

Test panels were placed in the QUV Acceler-ated Weathering Tester. The cycle consisted of fourhours of UV radiation (during which time tem-peratures reached approximately 35◦F (1.5◦C)) andfour hours with no UV radiation. A water bathat the bottom of the unit is maintained at 100◦F(38◦C) to create a constant high humidity condition.

After 3000 hours of continuous testing, the Elastuff101/102 system showed no surface checking orcracking, no delamination or loss of flexibility, andno chalking.[212]

Weathering Properties:Stabilization

The weathering of polyurethanes based on meta-tetramethylxylene diisocyanate TMXDI (META)aliphatic isocyanate is similar to that of otheraliphatic isocyanates in that surface quality and glossretention are excellent. Both TMXDI (META) andan H12MDI system for urethane roof topcoats wereexposed in a xenon arc weatherometer. QUV valueswere found to be similar to the xenon data reported.The weatherability of TMXDI (META) aliphaticisocyanate exceeds that observed for the H12MDIsystem.[213]

Although the molecule of TMXDI (META)aliphatic isocyanate is built around an aromatic ring,the isocyanate functionalities are not conjugated andare aliphatic. Thus, the quinoid structures that giverise to the poor weatherability of true aromatics, suchas toluene diisocyanate, are not possible. In addition,the presence of methyl groups in the place of benzylichydrogens further enhances the UV stability.[213]

392 The Effects of UV Light and Weather on Plastics and Elastomers

Weathering Properties by Material Supplier Trade Name

Table 76-1. Gloss Retained after Xenon Arc Accelerated Weatherometer Exposure of PolyurethaneRubber

Graph 76-1. Change in Color, �b, after Florida Outdoor Weathering of Polyurethane.

Chapter 77

Silicone Rubber

Category: Silicone, thermoset.

General Properties: Silicone rubber is a uniquesynthetic elastomer made from a cross-linkable poly-mer which is reinforced with silica. Dow CorningSilastic® is a ready-to-use blend of a silicone rub-ber base, fillers, modifiers, vulcanizing agents, andpigments.[214]

Weathering Properties

The weathering characteristics of Dow CorningSilastic® silicone rubber were tested at two sites:Southern Florida and Central Michigan (USA). Alltest specimens were prepared and mounted in accor-dance with ASTM D518, Method A, and were ina stressed condition, faced southward, and tilted

Weathering Properties by Material Supplier Trade Name

Table 77-1. Change in Mechanical Properties after Florida and Michigan Outdoor Weathering for DowCorning Silastic® Silicone Rubber as per ASTM D518, Method A

Material Family Silicone Rubber

Material Supplier Corning Silastic® Silicone Rubber

Reference Number 214

Exposure Conditions ASTM D518, Method A

Exposure Location Michigan Michigan Michigan Florida

Exposure Time 1 year 2 years 5 years 20 years

PROPERTY CHANGE

Tensile Strength (%) +8 to −25 +4 to −22 +22 to −27 −31

Elongation (%) +4 to −28 +14 to −34 −55

Hardness (Point Change) +3 to −6 +2 to −6 +8 to −9 +7

upward to catch the full impact of the elements.Because no cracking or checking developed in anySilastic® silicone rubber, an additional evaluationprocedure was used—ASTM D518, Method B. Peri-odically, some samples were removed, cut into stan-dard tensile bars, and tested for tensile strength,durometer hardness, and ultimate elongation. Formost elastomers, this added test is too severe, becauseeven the smallest crack will start a tear and yieldvery low tensile strength. In general, Test Method Bprovides a more stringent weathering test than TestMethod A.[214]

A visual inspection of the weathered Silastic®

silicone rubber samples from the Florida test stationshowed minor surface checking after 234 months(equivalent to 27,799 sun hours).[214]

Note: Samples were conditioned using MethodA andMethod B of ASTM D518.

394 The Effects of UV Light and Weather on Plastics and Elastomers

Table 77-2. Change in Mechanical Properties after Florida and Michigan Outdoor Weathering for DowCorning Silastic® Silicone Rubber as per ASTM D518, Method B

Material Family Silicone Rubber

Material Supplier Corning Silastic® Silicone Rubber

Reference Number 214

Exposure Conditions ASTM D518, Method B

Exposure Location Michigan Michigan Michigan Florida

Exposure Time 1 year 2 years 5 years 20 years

PROPERTY CHANGE

Tensile Strength (%) 0 to −23 −8 to −42 −14 to −54 −41

Elongation (%) +4 to −40 0 to −45 −24 to −50 −60

Hardness (Point Change) +1 to −8 −3 to −16 +5 to −8 +2

Appendix 1

Fluoropolymers in Coating Applications

Architectural Fabrics

Architectural fabrics are engineered materialsthat are available to architects and engineers for thedesign and construction of textile structures. Theyare flexible and strong and offer the designer manyoptions with respect to strength, aesthetic require-ments, fire codes, weatherability, expected lifetime,and more.

Most tensile structures utilize fabrics rather thanmeshes or films. Two basic families of fabrics areavailable—woven fabrics that consist of two sets ofyarns (warp and weft) woven together in a loomand foils that are made of thinly rolled or extrudedhomogenous material. Coatings and top finishes areapplied to provide aesthetics as well as to pro-tect the materials from UV radiation, moisture, dirtand/or chemicals. Coatings can also add strengthto a fabric. The most widely used materials arewoven polyester cloths coated with polyvinyl chlo-ride (PVC) and woven fiberglass coated with eitherpolytetrafluoroethylene (PTFE) or silicone.

Fabric Base Materials

• PTFE is a high strength, waterproofmaterial completely immune to UVradiation. DuPont Teflon® is a PTFE.

• Kevlar® is extremely strong (threetimes the strength of steel on an equalweight basis) with good abrasion resis-tance and little chemical and thermaldegradation. However, it is subject toUV deterioration. Kevlar® coated withPVC has found a few high-strengtharchitectural applications.

• Polyethylene can be made into an archi-tectural fabric with impressive tensileand tear strength and a life span equal toPVC. Polyethylene fabrics are unique

in that both the fabric and the coatingare made of polyethylene.

• Polyester base cloth is used because ofits durability, strength, and relativelylow cost. It is woven or knitted tohighly controlled specifications to givethe fabric strength, visual consistency,and measurable properties of stretchand strength.

• Woven glass fiber, often called fiber-glass, is commonly used as a base fabricfor silicone and PTFE-coated applica-tions. The coated glass fabric is inert,ages well, and does not emit toxicgases.

Fabric Coatings

• PVC is the most commonly used coat-ing for architectural purposes. PVC canbe made flexible and flame retardant byadding chemical compounds. Throughthe addition of a topcoat, the outdoorlife of PVC can be increased and itstendency to attract dirt can be reduced.

Fabric Top Finishes or Topcoats

Most architectural materials have some sort oftop finishes applied to their exterior or weatheringsurface. Top finishes to architectural fabrics provideprotection from UV degradation, water and winddamage, repel dirt, and can provide a pleasing aes-thetic component to the material. If the top finishdeteriorates and exposes the PVC beneath it, the PVCwill begin to lose its aesthetic benefit. The applica-tion of a proper top finish improves the appearance ofthe materials, and produces a material that will resist

396 The Effects of UV Light and Weather on Plastics and Elastomers

environmental elements and retain a bright, cleanappearance over the expected life of the structure.

Typical PVC topcoats are acrylic lacquers,polyvinylidene fluoride (PVDF) coatings, andpolyvinyl fluoride (PVF) laminates.

• Acrylic is the most economical andmost widely available finish. It isapplied as a thin spray-applied solutionthat gives a transparent glossy finishto the PVC. Acrylics generally havefair to good resistance to UV degra-dation. Acrylic topcoats are ideal forfabrics that are used for temporarystructures and demountable structuressuch as marquees, circus tents, andwarehouses.

• PVDF is made up of 59% fluorine, 38%carbon, and 3% hydrogen and is bondedto the PVC. PVDF offers resistanceto UV degradation and atmosphericchemical attack, which is far superiorto the acrylic topcoat. Controlled expo-sure tests in Florida indicate that changein color and gloss are significantly less,over time, than its acrylic counterpart.PVDF topcoats also offer resistance toalgae and fungal attack.They have goodself-cleaning properties and thereforeneed little maintenance. These prop-erties combine to give the membranea life span of 15–20 years dependingon site conditions. PVDF is usuallycompounded with acrylics for outdoorcoating applications to reduce cost andmake it heat sealable.

• PVF belongs to the same polymerfamily as Teflon®, and the DuPonttrade name is Tedlar®. PVF is bondedto the vinyl fabric in film form ina laminating process and results in athicker finished fabric that is resistantto degradation from UV radiation, isdurable, and maintains its essenti-ally “self-cleaning” attributes resisting

attack from graffiti, acid rain, and birddroppings. Having a thicker coating, iterodes at a much slower rate givingit a life expectancy of about 25 yearsdepending on conditions. The Tedlar®

film topcoating not only resists environ-mental degradation but also eliminatesthe migration of plasticizers from thebase PVC coating. Tedlar® does notcontain a plasticizer. The Tedlar® top-coating is flexible, allowing a consis-tent and strong bond to the PVC. PVFis frequently specified for use in highlyindustrialized areas, high saline coastalzones, and desert environments.

• PVDF/PVC topcoating is effectivelya dilution of the PVDF topcoat. Thisgives the finished fabric the advantagesof being less expensive to produce andto fabricate. The diluted effect of thePVDF, however, means that environ-mental resistance is reduced along withlongevity. Fabrics with this coatinghave a life expectancy of 10–15 years,depending on prevailing conditions.

Weathering Resistance

Seven different commercially available materi-als were evaluated by DuPont. All were white andwere promoted by their manufacturers as architec-tural fabrics for commercial use today. All sevensamples were subjected to accelerated weatheringand were monitored at selected intervals. The thick-ness of the protective layer was measured by opticalmicroscopy or by transmission electron microscopy(TEM). Color and 60◦ gloss change were recordedas well.[215]

After 2.5 years of natural weathering, the acrylicand PVDF coatings show significant dirt accumu-lation and discoloration, while the fabric bondedwith Tedlar® PVF shows no signs of discolorationor significant dirt accumulation.[215]

Appendix 1: Fluoropolymers in Coating Applications 397

Graph A1-1. Top Finish Thickness after Accelerated Florida Outdoor Exposure Testing for Acrylic, PVDF, andDuPont Tedlar® PVF Top Finishes.[215]

Years of Simulated Florida Outdoor Exposure4.0

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Pro

tect

ion

thic

knes

s (m

il)

0.0 1.3 2.7 5.3 6.7 8.0 9.3

Acrylic “A” Topcoat

Acrylic “B” Topcoat

Tedlar® PVF Film

Acrylic “C” Topcoat

PVDF “A” Topcoat

PVDF “B” Topcoat

PVDF “C” Topcoat

Graph A1-2. Color Change, �E, after Accelerated Florida Outdoor Exposure Testing for Acrylic, PVDF, andDuPont Tedlar® PVF Top Finishes.[215]

0

2

4

6

8

10

12

Col

or C

hang

e (∆

E)

Years of Simulated Florida Outdoor Exposure0.0 1.3 2.7 4.0 5.3 6.7 8.0 9.3

Acrylic “A” TopcoatAcrylic “B” Topcoat

Tedlar® PVF Film

Acrylic “C” TopcoatPVDF “A” TopcoatPVDF “B” TopcoatPVDF “C” Topcoat

398 The Effects of UV Light and Weather on Plastics and Elastomers

Graph A1-3. Gloss Change, 60◦ Gloss, after Accelerated Florida Outdoor Exposure Testing for Acrylic, PVDF,and DuPont Tedlar® PVF Top Finishes.[215]

0

10

20

30

40

50

60

70

Years of Simulated Florida Outdoor Exposure

60°

Glo

ss

0.0 1.3 2.7 4.0 5.3 6.7 8.0 9.3

Acrylic “A” TopcoatAcrylic “B” Topcoat

Tedlar® PVF Film

Acrylic “C” TopcoatPVDF “A” TopcoatPVDF “B” TopcoatPVDF “C” Topcoat

Note: Exposures of 1200 kJ are equivalent to one year of South Florida exposure at an angle of 45◦ from the horizontal.

Appendix 2

Coil Coatings

Comparative Properties andPerformance Chart

Coil Coating Topcoats

The Comparative Properties and PerformanceChart has been created to provide a description ofthe physical and performance properties of variouscoil coating topcoats. This chart has been prepared to

Table A2-1. Comparative Properties and Performance Chart—Coil Coating Topcoats[216]

PolyesterWeathering ASTM Plastisol Solution Interior Use Silicone Polyvinylidene Acrylic PolyurethaneProperties Method Acrylic Only/Exterior Use Polyester Fluoride Latex

Gloss Retention G7, 2–3 3 N/A 3–4 4 5 3–4 3–45 Years Florida, D1014,45◦ South D523

Chalk G7, 2–3 3 N/A 3–4 4 5 3–4 3–45 Years Florida, D1014,45◦ South D4214

Color Retention G7, 2–3 3 N/A 3–4 4 5 3–4 3–45 Years Florida, D1014,45◦ South D2244

5, excellent; 4, very good; 3, good; 2, fair; 1, poor.This chart has been prepared by The National Coil Coaters Association Technology Committee.

provide only general information. It is neither a per-formance standard nor a specification. It describesbroad performance criteria and should never be usedon its own to select a particular coating technol-ogy for a specific application. A wide range ofperformance criteria exist within any generic coat-ing category. It is advisable to consult the coatingsuppliers regarding your specific needs.

Glossary of Terms

A

AATCC method 16: A method developed by theAmerican Association of Textile Chemists and Col-orists for the accelerated testing of the colorfastnessof fabrics and yarns to light. Exposure conditions are:for option A—continuous borosilicate glass-filteredcore/solid carbon-arc lamp irradiation, optionC—continuous daylight carbon-arc lamp irradiation,option D—same as optionAbut alternating with darkperiods, option E—continuous borosilicate/soda-lime glass-filtered water-cooled xenon-arc lamp irra-diation, option F—same as option E but alternatingwith dark periods, option I—continuous soda-limeglass-filtered air-cooled xenon-arc lamp irradiation,option J—same as option I but alternating with darkperiods. The color change of white card-mountedspecimens is evaluated by rating against AATCCgray scale, colorimetry in AATCC fading units, ordetermination of �E value. The exposure stages aredetermined with simultaneously exposed AATCCBlue Wool Standards or reference specimens. Alsocalled AATCC method 16C.

AATCC method 16C: See AATCC method 16.

AATCC method 111B: A method developed bythe American Association of Textile Chemists andColorists for the weather resistance testing of fabricsand yarns. The specimens, secured in special frames,are exposed to natural sunlight and weathered aroundthe clock in uncovered cabinets with or without back-ing on racks facing the equator. The conditions ofthe test are recorded by measuring maximum andminimum temperatures and relative humidity val-ues, hours of wetness for rain and rain plus dew,and total and UV radiant energy. The weatherabi-lity of the specimens is assessed by comparing withstandard samples and by measuring the percentageresidual strength (breaking, tearing, or burst) and/orcolorfastness.

AATCC method 111D: A method developed bythe American Association of Textile Chemists andColorists for testing the resistance of fabrics andyarns to weather, excluding precipitation. The spec-imens, secured in special frames, are exposed tonatural sunlight and weathered around the clock inglass-covered ventilated cabinets with backing onsloped racks. The glass is 2.0–2.5 mm thick, absorb-ing radiation less than 310 nm. The conditions of thetest are recorded by measuring maximum and mini-mum temperatures and relative humidity values, andradiant energy. The weatherability of the specimensis assessed by comparing with standard samplesand by measuring the percentage residual strength(breaking, tearing, or burst) and/or colorfastness.

AATCC method 169: A method developed bythe American Association of Textile Chemists andColorists for the accelerated testing of the resis-tance of fabrics and yarns to weather in an artificialweathering apparatus. The specimens are exposed towater- or air-cooled long arc xenon lamp irradia-tion on variously positioned racks at different radiantenergy levels. In the semitropical climate exposure(option 1), the specimens are irradiated for 90 min-utes and water-sprayed for 30 minutes at 77◦C and70% relative humidity. In the arid climate expo-sure (option 3), the specimens are irradiated only.In the Columbus, Ohio, climate exposure (option 4),the specimens are irradiated at 102 minutes andwater-sprayed for 18 minutes at 63◦C and 50% rel-ative humidity. The weatherability of the specimensis assessed by comparing with standard samplesand by measuring the percentage residual strength(breaking, tearing, or burst) and/or colorfastness.

ABS: See acrylonitrile-butadiene-styrene polymer.

ABS nylon alloy: See acrylonitrile-butadiene-styrene polymer nylon alloy.

ABS PC alloy: See acrylonitrile-butadiene-styrenepolymer polycarbonate alloy.

402 The Effects of UV Light and Weather on Plastics and Elastomers

ABS resin: See acrylonitrile-butadiene-styrenepolymer.

accelerant: See accelerator.

accelerated indoor colorfastness test: See accel-erated indoor light colorfastness test.

accelerated indoor light colorfastness test: Anindoor test that measures the resistance of a coloredplastic to fading and/or discoloration on prolongedexposure to a common source of UVradiation such assunlight, glass-filtered daylight, or fluorescent light-ing. The test is performed in controlled simulatedenvironments using artificial light sources at highlevels of radiance to reduce the test time. The sourcesused include xenon arc, carbon arc, and fluorescentlamps. Also called accelerated indoor colorfastnesstest.

accelerator: A chemical substance that accelerateschemical, photochemical, biochemical, etc. reac-tions or processes, such as cross-linking or degrada-tion of polymers, that is triggered and/or sustained byanother substance, such as a curing agent or catalyst,or environmental factors, such as heat, radiation, ora microorganism. Also called accelerant, promoter,cocatalyst.

acetal resins: Thermoplastics prepared by the poly-merization of formaldehyde or its trioxane trimer.Acetals have high impact strength and stiffness, lowfriction coefficient and permeability, good dimen-sional stability and dielectric properties, and highfatigue strength and thermal stability. Acetals havepoor acid and UV resistance and are flammable. Pro-cessed by injection and blow molding and extrusion.Used in mechanical parts such as gears and bearings,automotive components, appliances, and plumbingand electronic applications. Also called acetals.

acetals: See acetal resins.

acrylate-styrene-acrylonitrile polymer: Acrylicrubber-modified thermoplastic with high weather-ability. ASA has good heat and chemical resistance,toughness, rigidity, and antistatic properties. Pro-cessed by extrusion, thermoforming, and molding.

Used in construction, leisure, and automotive appli-cations such as siding, exterior auto trim, and outdoorfurniture. Also called ASA.

acrylic resins: Thermoplastic polymers of alkylacrylates such as methyl methacrylates. Acrylicresins have good optical clarity, weatherability, sur-face hardness, chemical resistance, rigidity, impactstrength, and dimensional stability. They have poorsolvent resistance, resistance to stress cracking, flex-ibility, and thermal stability. Processed by casting,extrusion, injection molding, and thermoforming.Used in transparent parts, auto trim, householditems, light fixtures, and medical devices.Also calledpolyacrylates.

acrylonitrile-butadiene-styrene polymer: ABSresins are thermoplastics comprising a mixture ofstyrene-acrylonitrile copolymer (SAN) and SAN-grafted butadiene rubber. They have high impactresistance, toughness, rigidity, and processability,but low dielectric strength, continuous servicetemperature, and elongation. Outdoor use requiresprotective coatings in some cases. Plating gradesprovide excellent adhesion to metals. Processedby extrusion, blow molding, thermoforming, calen-daring, and injection molding. Used in householdappliances, tools, nonfood packaging, businessmachinery, interior automotive parts, extrudedsheets, pipes and pipe fittings.Also calledABS,ABSresin.

acrylonitrile-butadiene-styrene polymer nylonalloy: Athermoplastic processed by injection mold-ing, with properties similar to ABS but higherelongation at yield. Also called ABS nylon alloy.

acrylonitrile-butadiene-styrene polymer polycar-bonate alloy: A thermoplastic processed by injec-tion molding and extrusion, with properties similartoABS. Used in automotive applications.Also calledABS-PC alloy.

acrylonitrile copolymer: Athermoplastic preparedby copolymerization of acrylonitrile with smallamounts of other unsaturated monomers. Has goodgas barrier properties and chemical resistance. Pro-cessed by extrusion, injection molding, and thermo-forming. Used in food packaging.

Glossary of Terms 403

alcohols: A class of hydroxy compounds in whicha hydroxy group(s) is attached to a carbon chainor ring. Alcohols are produced synthetically frompetroleum stock (e.g., by hydration of ethylene) orderived from natural products (e.g., by fermentationof grain). Alcohols are divided into the follow-ing groups: monohydric, dihydric, trihydric, andpolyhydric. Used in organic synthesis as solvents,plasticizers, fuels, beverages, detergents, etc.

amorphous nylon: Transparent aromatic poly-amide thermoplastics.

anatase TiO2: See anatase titanium dioxide.

anatase titanium dioxide: One of the naturallyoccurring crystal forms of titanium dioxide. Usedas a white or opacifying pigment in a wide rangeof materials including coatings and plastics. Anatasetitanium dioxide has a lower refractive index andopacity than rutile titanium dioxide, another crystalform of this oxide.The pigment is nonmigrating, heatresistant, chemically inert, and lightfast. Also calledanatase TiO2.

annulus test: An ozone resistance test for rubbersthat involves a flat-ring specimen mounted as a bandover a rack, stretched 0–100% and subjected to ozoneattack in the test chamber. The specimen is evaluatedby comparing to a calibrated template to determinethe minimum elongation at which cracking occurs.

anthraquinone: An aromatic compound compris-ing two benzene rings linked by two carbonyl (C=O)groups, C6H4(CO)2C6H4. Combustible. Used as anintermediate in organic synthesis, mainly in themanufacture of anthraquinone dyes and pigments.One method of preparation is by condensation of1,4-naphthaquinone with butadiene.

antioxidant: A chemical substance capable ofinhibiting oxidation or oxidative degradation ofanother substance such as a plastic in which it isincorporated. Antioxidants act by terminating chain-propagating free radicals or by decomposing perox-ides, formed during oxidation, into stable products.The first group of antioxidants include hindered phe-nols and amines, the second group include sulfurcompounds such as thiols.

Arizona aging: An outdoor exposure test per-formed in Arizona, USA, under climatic conditionscharacterized by high annual solar radiation and tem-perature to evaluate the weatherability of materialssuch as coatings or plastics. Special panels with spec-imens are exposed at a standard tilt angle for 6–48months. The aging of the specimens is assessed visu-ally and by measuring the changes in color, surface,mechanical (e.g., hardness and tensile strength) andother properties.

aromatic polyester estercarbonate: Athermoplas-tic block copolymer of an aromatic polyester withpolycarbonate. Has higher heat distortion tempera-ture than regular polycarbonate.

aromatic polyesters: Engineering thermoplasticsprepared by the polymerization of aromatic poly-ols with aromatic dicarboxylic anhydrides. They aretough with somewhat low chemical resistance. Pro-cessed by injection and blow molding, extrusion, andthermoforming. Drying is required. Used in auto-motive housings and trim, electrical wire jacketing,printed circuit boards, and appliance enclosures.

artificial accelerated weathering: An indoor testin which a material, such as plastic, is exposedto simulated outdoor conditions (sunlight, tempera-ture changes, humidity, marine environment) harsherthan normal to produce changes or degradationfaster. The test is performed in a controlled envi-ronment such as a climatic or weathering chamberwith artificial light sources like xenon arc lamps. Theweathering of the specimens is assessed visually andby measuring the changes in color, surface, mechan-ical (e.g., hardness and tensile strength) and otherproperties.

ASA: See acrylate-styrene-acrylonitrile polymer.

Aspergillus flavus: A species of common moldbelonging to the genus Aspergillus. Used alone orin artificial mixtures with other fungi to prepare cul-tures for the testing of mildew resistance of materialssuch as plastics, or fungicidal activity of antimildewagents or fungicides.

Aspergillus niger: A species of common moldbelonging to the genus Aspergillus. Used alone or

404 The Effects of UV Light and Weather on Plastics and Elastomers

in artificial mixtures with other fungi to prepare cul-tures for the testing of mildew resistance of materialssuch as plastics, or fungicidal activity of antimildewagents or fungicides.

Aspergillus versicolor: A species of common moldbelonging to the genus Aspergillus. Used alone orin artificial mixtures with other fungi to prepare cul-tures for the testing of mildew resistance of materialssuch as plastics, or fungicidal activity of antimildewagents or fungicides.

ASTM B117: An American Society for Testing ofMaterials standard method for salt spray (fog) testingof materials such as metallic and nonmetallic coat-ings on metal substrates. The specimens are exposedto a fine spray of a NaCl solution at about 35◦C in aspecial chamber for an extended period of time. Theresults are assessed visually by checking for a spec-ified extent of corrosion damage or by a measuringtechnique such as impedance.

ASTM B368: An American Society for Testing ofMaterials standard method for copper-acceleratedacetic acid-salt spray (fog) testing of copper-nickel-chromium or nickel-chromium coatings on metaland plastic substrates. The method sets forth testconditions for evaluating anticorrosive properties ofcoatings exposed to a fine spray of a NaCl-CuCl2-AcOH solution (pH 3.1–3.3) at about 49◦C in aspecial chamber for 6–720 hours. The results areassessed by measuring the rate of corrosion (i.e.,weight loss per unit area of the test panel).

ASTM C793: An American Society for Testing ofMaterials standard method for testing the effects ofaccelerated weathering on elastomeric joint sealantsused in building construction.The sealants are spreadon aluminum plates and exposed to 250 hours of UVradiation with intermittent water spray in a weather-ing chamber, followed by freezing at about −26◦Cfor 24 hours with subsequent bending over a mandrelat a specified temperature, The results are evaluatedby visual examination of the specimens for cracks.

ASTM D256: An American Society for Testing ofMaterials standard method for determination of theresistance to breakage by flexural shock of plasticsand electrical insulating materials, as indicated bythe energy extracted from standard pendulum-type

hammers in breaking standard specimens with onependulum swing. The hammers are mounted on stan-dard machines of either Izod or Charpy type. Note:Impact properties determined include Izod or Charpyimpact energy normalized per width of the specimen.Also calledASTM method D256-84. See also impactenergy.

ASTM D279: An American Society for Testingof Materials standard method for determining thebleeding (migration) characteristics of dry pigmentsby direct solvent extraction of the pigment, or byoverstriping a film containing the pigment with awhite coating and observing for the color migrationfrom the base coat containing the pigment. Duringextraction, the pigment is shaken with toluene, fil-tered, and the filtrate is observed for color.The degreeof bleeding is rated from none to severe.

ASTM D395: An American Society for Testing ofMaterial standard method for testing the capacityof rubber to recover from compressive stress in airor liquid media. The specimen is subjected to com-pression by a specified force for a definite time ata specified temperature. The difference between theoriginal and the final specimen thickness or com-pression set is calculated as a percentage of theoriginal thickness by measuring the final thickness30 minutes after stress removal.

ASTM D412: An American Society for Testing ofMaterials standard method for determining tensilestrength, tensile stress, ultimate elongation, tensileset, and set after break of rubber at low, ambient, andelevated temperatures using straight, dumbbell, andcut-ring specimens.

ASTM D471: An American Society for Testingof Materials standard method for determining theresistance of nonporous rubber to hydrocarbon oils,fuels, service fluids, and water. The specimens areimmersed in fluids for 22–670 hours at −75 to250◦C, followed by measuring of the changes inmass, volume, tensile strength, elongation, and hard-ness for solid specimens, and the changes in breakingstrength, burst strength, tear strength, and adhesionfor rubber-coated fabrics.

Glossary of Terms 405

ASTM D570: An American Society for Testing ofMaterials standard method for determining the rel-ative rate of water absorption of immersed plastics.The test applies to all kinds of plastics: molded, cast,laminated, etc. The specimens are immersed for 2–24 hours or until saturation at ambient temperature,or for 0.5–2 hours in boiling water. The absorptionis calculated as a percentage of weight gain.

ASTM D638: An American Society for Testing ofMaterials standard method for determination of thetensile properties of unreinforced and reinforcedplastics in the form of standard dumbbell-shapedspecimens under defined conditions of pretreatment,temperature, humidity, and testing machine speed.Note: Tensile properties determined include tensilestress (strength) at yield and at break, percentageelongation at yield or at break, and modulus of elas-ticity. Also called ASTM method D638-84. See alsotensile strength.

ASTM D638: An American Society for Testingof Materials standard method for determining thetensile strength, elongation, and modulus of elas-ticity of reinforced or unreinforced plastics in theform of sheets, plates, moldings, rigid tubes, androds. Five (I–V) types, depending on dimensions,of dumbbell-shaped specimens with thickness notexceeding 14 mm are specified. Specified speed oftesting varies depending on the specimen type andplastic rigidity. Also called ASTM D638, type IV.

ASTM D638, type IV: See ASTM D638.

ASTM D746: An American Society for Testing ofMaterials standard method for determining the brit-tleness temperature of plastics and elastomers byimpact. The brittleness temperature is the temper-ature at which 50% of cantilever beam specimensfail on impact of a striking edge moving at a linearspeed of 1.8–2.1 m/s and striking the specimen at aspecified distance from the clamp. The temperatureof the specimen is controlled by placing it in a heat-transfer medium, the temperature of which (usuallysubfreezing) is controlled by a thermocouple.

ASTM D750: An American Society for Testing ofMaterials standard method for the testing of rubberdeterioration in carbon-arc or weathering apparatus.Vulcanized rubber specimens are exposed to the light

of a carbon arc lamp simulating the sunlight with orwithout strain and sprayed with water for 18 min-utes every 102 minutes. Testing may be carried outin the presence of ozone. The aging is evaluated aftera specified duration of exposure by determining thepercentage decrease in tensile strength and elonga-tion at break, and by observing the extent of surfacecrazing and cracking.

ASTM D1003: An American Society for Testing ofMaterials standard method for measuring the hazeand luminous transmittance of transparent plasticsusing a hazemeter or spectrophotometer.

ASTM D-1925-63T: See ASTM D1925.

ASTM D1006: An American Society for Testingof Materials standard practice for conducting exte-rior exposure tests of house and trim paints on newwood. Painted testing panels (boards or plywood)are exposed for several years on vertical fences fac-ing both north and south and visually examined forfailures at prescribed intervals (1–6 months).

ASTM D1171: An American Society for Testing ofMaterials standard method for determining the resis-tance of rubber to outdoor weathering and to surfaceozone cracking in a special chamber. The specimenswith triangular cross sections are mounted strainedaround circular mandrels and exposed outdoorsfor a specified period of time or in the chamber for72 hours at about 40ºC and ozone partial pressureof about 50 MPa. After the exposure the specimensare compared to the reference standards to evalu-ate the degree of cracking in terms of a rating. Alsocalled ASTM D1171 Loop.

ASTM D1171 Loop: See ASTM D1171.

ASTM D1435: An American Society for Testing ofMaterials standard practice for outdoor weatheringof plastics. The specimens are mounted on specialracks at different tilts and exposed outdoors for anextended period of time while the solar radiation,temperature, rainfall, etc., are measured. The weath-ering of the specimens is assessed visually and bymeasuring the changes in color, surface, mechani-cal (e.g., hardness and tensile strength), and otherproperties.

406 The Effects of UV Light and Weather on Plastics and Elastomers

ASTM D1499: An American Society for Testingof Materials standard practice for operating light-and water-exposure apparatus for plastics. The spec-imens are exposed to light from a carbon arc lamp andintermittent water spray (18 minutes every 2 hours)at about 63◦C for 720 hours. The degradation of thespecimens is assessed visually and by measuring thechanges in surface, color, mechanical (e.g., hardnessand tensile strength), and other properties.

ASTM D1708: An American Society for Testingof Materials standard method for determining thetensile properties of plastics using microtensile spec-imens with a maximum thickness of 3.2 mm and aminimum length of 38.1 mm, including thin films.Tensile properties include yield strength, tensilestrength, tensile strength at break, elongation atbreak, etc., determined as per ASTM D638.

ASTM D1925: An American Society for Testingof Materials standard method for determining theyellowness index or its change for clear or whiteplastics exposed 10 daylight as measured by aspectrophotometer. Also called ASTM D-1925-63T.

ASTM D2240: An American Society for Testing ofMaterials standard method for determining the hard-ness of materials ranging from soft rubbers to somerigid plastics by measuring the penetration of a blunt(type A) or sharp (type D) indenter of a durome-ter at a specified force. The blunt indenter is used forsofter materials and the sharp indenter for more rigidmaterials.

ASTM D2565: An American Society for Testing ofMaterials standard practice for operating xenon arc-type light exposure apparatus with or without waterspray exposure for plastics. The practice specifiesthe number and the location of xenon arc lamps andother characteristics of the apparatus and the speci-mens. The xenon arc lamps used may be water- orair-cooled and are equipped with a proper filter tosimulate sunlight.The test is conducted for 720 hoursat about 63◦C and at a specified intensity of radiation.The degradation of the specimens is assessed visu-ally and by measuring the changes in surface, color,mechanical (e.g., hardness and tensile strength), andother properties.

ASTM D3679: An American Society for Testingof Materials standard specification for extrudedsingle-wall rigid polyvinyl chloride siding that estab-lishes its physical requirements (dimensions, weight,weatherability, impact resistance, expansion, shrink-age, and appearance) and test methods for physicalrequirements and marking.

ASTM D3763: An American Society for Testing ofMaterials standard method for determination of theresistance of plastics, including films, to high-speedpuncture over a broad range of test velocities usingload and displacement sensors. Note: Puncture prop-erties determined include maximum load, deflectionto maximum load point, energy to maximum loadpoint, and total energy. Also called ASTM methodD3763-86. See also impact energy.

ASTM D3841: An American Society for Test-ing of Materials standard specification for glassfiber-reinforced polyester construction panels. Thespecification covers classification, inspection, cer-tification, dimensions, weight, appearance, lighttransmission, weatherability, expansion, impactresistance, flammability, and load-deflection proper-ties of panels and their methods of testing.

ASTM D4141: An American Society for Testing ofMaterials standard practice for conducting acceler-ated outdoor exposure tests for evaluating exteriordurability of coatings applied to metal substrates.The degradation of coatings is accelerated by max-imizing the temperature, using a heated (ProcedureB) or unheated (Procedure A) black box panel, orby maximizing sunlight irradiation, using a Fresnelreflector (Procedure C) panel. A black box panel is acoated metal panel mounted as a closure on a blackbox to simulate the conditions on the hoods, roofs,and deck leads of automobiles parked in direct sun-light. The degradation of the specimens is evaluatedby measuring loss of gloss, discoloration, checking,cracking, chalking, and blistering.Also calledASTMD4141-A&B.

ASTM D4141-A&B: See ASTM D4141.

ASTM D4275: An American Society for Testingof Materials standard method for determination ofbutylated hydroxytoluene in ethylene polymers and

Glossary of Terms 407

ethylene-vinyl acetate copolymers by solvent extrac-tion followed by gas chromatographic analysis.Detection of butylated hydroxytoluene is achievedby flame ionization. Butylated hydroxytoluene is astabilizer used in the manufacture of the ethylenepolymers.

ASTM D4434: An American Society for Testingof Materials standard specification for polyvinylchloride sheet roofing, used as a single-ply roofmembrane. The material may be unreinforced orreinforced and may contain fibers or fabrics. Thespecification specifies types, dimensions, mechan-ical properties, weatherability, resistance to heataging, appearance, and test methods. The mechan-ical properties tested include tensile strength andelongation at break, seam strength, tear resistance,and tearing strength. The exposure tests includeaccelerated weathering, water exposure, xenon arclight exposure, and fluorescent UV/condensationexposure. Also called ASTM DS D4434.

ASTM D4637: An American Society for Test-ing of Materials standard specification for unrein-forced or fabric-reinforced vulcanized rubber sheetsmade from EPDM or chloroprene rubber and usedas single-ply roof membranes. The specificationspecifies grades, dimensions, mechanical proper-ties, weatherability, resistance to ozone and heataging, appearance, and test methods. The mechan-ical properties tested include tensile strength, setand elongation, seam strength, tear resistance, andtearing strength. The exposure tests include waterabsorption. Also called ASTM DS D4637.

ASTM D5071: An American Society for Testingof Materials standard practice for operating xenonarc-type light exposure apparatus with water sprayexposure of photodegradable plastics. The practicespecifies the type and irradiance capability of xenonarc lamps and other characteristics of the apparatusand the specimens. The xenon arc lamps used musthave a proper filter to simulate sunlight. The test isconducted for a specified time at about 63◦C anda specified intensity of radiation. Alternating lightand dark periods with moisture test programs arerecommended. The degradation of the specimens isassessed visually and by measuring the changes insurface, color, mechanical (e.g., hardness and tensilestrength), and other properties.

ASTM DS D4434: See ASTM D4434.

ASTM DS D4637: See ASTM D4637.

ASTM E42: See ASTM G23.

ASTM E42-57: See ASTM G23.

ASTM E313: An American Society for Testing ofMaterials standard method for determination of theindexes of whiteness and yellowness of near-white,opaque materials such as textiles, paints, and plastics.The whiteness or yellowness indexes are one-scalecolorimetric attributes measured with a spectropho-tometer or a colorimeter having green and bluesource-filter-photodetector combination. The yel-lowness index is calculated as 100(1 − B/G), whereB is the blue light reflectance and G is the daylightluminous reflectance of the specimen. The whitenessindex is calculated as 4B − 3G. G and B are pro-portional to the light flux reflected by the specimenfor the CIE Source C when viewed under specifiedgeometric conditions by a receptor whose spectralresponse duplicates the luminosity function y and z,respectively.

ASTM E838: See ASTM G90.

ASTM E896: An American Society for Testingof Materials standard method for determination ofphotolysis rates, quantum yields, and phototrans-formation products of materials that absorb lightdirectly (without the presence of light sensitizers) inaqueous media to estimate the environmental rates ofphotolysis (i.e., light-induced changes in the struc-ture of a molecule). A three-tier system of testingof increasing complexity is employed. The simplest,tier I test involves the measurement of the concentra-tion of residual material in aqueous solution after upto 6 hours of sunlight exposure. In the tier II test, pho-tolysis rate and rate constants are determined, and inthe tier III test phototransformation products. Alsocalled ASTM E896-92.

ASTM E896-92: See ASTM E896.

ASTM G7: An American Society for Testing ofMaterials standard practice for atmospheric environ-mental exposure (weathering) testing of nonmetallicmaterials. The practice specifies test variables that

408 The Effects of UV Light and Weather on Plastics and Elastomers

are important to produce consistent results. Thesevariables include exposure location; type, position,and construction of specimen panel racks; instru-mentation for determining climatological data suchas relative humidity; and type and duration of expo-sure. The types of exposure include direct weath-ering, exposure behind glass, sheltered storage, andundercover and warehouse exposure. The changes inspecimens are evaluated by rating against standards.

ASTM G23: An American Society for Testingof Materials standard practice for operating light-exposure apparatus with or without water spray fordetermination of lightfastness of nonmetallic materi-als. The specimens are exposed to light from a carbonarc lamp with or without alternating periods of dark-ness and intermittent water spray at about 63◦C fora specified extended period of time. The apparatus(weatherometers) used are as follows: type D—twinenclosed carbon-arc lamp apparatus with rotatingspecimen drum, type E—single open-flame sunshinecarbon-arc lamp apparatus with rotating specimenrack, type H—single enclosed carbon-arc lamp appa-ratus with rotating specimen rack. The degradationof the specimens is assessed visually and by measur-ing the changes in color, surface, mechanical (e.g.,hardness and tensile strength), and other properties.Also called ASTM E42, ASTM E42-57.

ASTM G26: An American Society for Testingof Materials standard practice for operating light-exposure apparatus with or without water spray fordetermination of lightfastness of nonmetallic mate-rials. The specimens are exposed to light from axenon arc lamp with or without alternating periods ofdarkness and intermittent water spray at about 63◦Cfor a specified extended period of time. The appa-ratus (weatherometers) used are as follows: type Aand B—water-cooled long-arc vertical xenon lampwith borosilicate glass filters, type C and D—singleair-cooled xenon-arc lamp apparatus with IR opticalfilters, type E—triple xenon-arc lamp apparatus withER optical filters. The degradation of the specimensis assessed visually and by measuring the changes incolor, mechanical (e.g., impact and tensile strength),and other properties.

ASTM G53: An American Society for Testing ofMaterials standard practice for operating light- andwater-exposure apparatus for determination of the

resistance to deterioration of nonmetallic materialsexposed to sunlight and water as rain and dew. Thespecimens are exposed alternately to light from afluorescent UV lamp and to condensation in a repet-itive cycle. Condensation, is produced by exposingone surface of the specimen to a heated, saturatedmixture of air and water vapor, while cooling theopposite surface. The degradation of the specimensis assessed visually and by measuring the changes incolor, surface, mechanical (e.g., hardness and tensilestrength), and other properties.

ASTM G85: An American Society for Testing ofMaterials standard practice for modified salt spray(fog) testing of materials such as metals, metalliccoatings, and nonmetallic coatings on metal sub-strates. The method sets forth the conditions for eval-uating anticorrosive properties of materials exposedto a fine spray of a saline solution at about 35◦C in aspecial chamber for an extended period of time. Thetest may be continuous or cyclic. The saline solutionmay be acetic acid-NaCl solution (pH 3.1–3.3), acid-ified seawater or SO2-NaCl solution. The results areassessed visually by checking for a specified extentof corrosion damage or by a measuring techniquesuch as impedance.

ASTM G90: An American Society for Testing ofMaterials standard practice for performing acceler-ated outdoor weathering of nonmetallic materialsusing natural sunlight concentrated by a Fresnelreflector without (type A) or with (type B) a peri-odic water spray to simulate arid or humid climaticconditions. The Fresnel reflector machine comprisesa system of flat mirrors that follows the sun withthe help of two photoreceptor cells to maximizeirradiation and temperature of specimen panels andaccelerate weathering. The total solar radiation doesis reported. The degradation of the specimens isassessed visually and by measuring the changes incolor, surface, mechanical (e.g., hardness and tensilestrength), and other properties. Also called ASTME838.

ASTM method D256-84: See ASTM D256.

ASTM method D3763-86: See ASTM D3763.

ASTM method D638-84: See ASTM D638.

Glossary of Terms 409

Atlas Ci65 xenon arc weatherometer: See xenonarc weatherometer.

Atlas fadeometer: See fadeometer.

Atlas UV-CON: See fluorescent UV lamp-condensation apparatus.

azo: A prefix indicating an organic group of twonitrogen atoms linked by a double bond, –N=N–,or a class of chemical compounds containing thisgroup, like azo dyes.

B

backed exposure rack: A rack for holding speci-mens or specimen panels during exposure testing thatis enclosed from the back to better control the effectof exposure on the exposed side of the specimen.

bending properties: See flexural properties.

bending strength: See flexural strength.

bending stress: See flexural stress.

benzotriazoles: A family of UV absorbers forplastics and rubbers, comprising derivatives of 2-(2′-hydroxyphenyl)benzotriazole. They offer strongintensity and broad UV absorption with fairly sharpwavelength cutoff close to the visible region. Higheralkyl derivatives arc less volatile and therefore moresuitable for higher temperature processing.

biodegradation: Microorganism-induced degrada-tion of the material that may involve a negativeeffect such as loss of performance and cracking of anunderground pipe or a positive effect such as decom-position of material waste to simple chemical com-pounds. Usually, the microorganisms such as fungiinduce biodegradation by generating the enzymesand proteins that catalyze degradation reactions.Also called microbiological attack.

bisphenol A polyester: A thermoset unsaturatedpolyester based on bisphenol A and fumaric acid.

black panel temperature: Temperature measuredby sensors mounted on the black-coated stainless

steel panel as specified in ASTM G26. It is usedas the standard reference to control an indoor light-exposure test temperature.

bleaching: Complete loss of color of the materialas a result of degradation or removal of coloredsubstances present on its surface. Bleaching can becaused by chemical reactions, radiation, etc.

blistering: The formation of bubbles on the surfaceof a nonmetallic coating or a plastic specimen orarticle as a result of air or other gases or evapora-tion of moisture or other volatiles trapped beneath.Blistering is often caused by improper applicationor excessive mixing of paints, heat, and polymerdegradation.

borosilicate outer filter: A borosilicate glass outerfilter of a xenon-arc lamp that in combination witha soda-lime or quartz inner filter selectively screensradiation output, especially in the short UV wave-length region, to simulate the window glass-filtereddaylight and sunlight, respectively, in an acceleratedlight exposure testing apparatus.

breaking elongation: See elongation.

bubbling: The presence of bubbles of trapped airand/or volatile vapors in nonmetallic coatings orplastic specimens or articles. Bubbling is oftencaused by improper application or excessive mixingof paints or degassing.

C

C.I. Pigment Orange 20: See cadmium orange.

C.I. Pigment Red 108: See cadmium red.

C.I. Pigment Yellow 37:1: See lithopone yellow.

CA: See cellulose acetate.

CAB: See cellulose acetate butyrate.

cadmium orange: An orange nonbleeding inor-ganic pigment based on cadmium sulfide and sulfos-elenide (Color Index Number 77202), having highlightfastness and good heat and alkali resistance.

410 The Effects of UV Light and Weather on Plastics and Elastomers

Used in PVC and polyolefin plastics, paints, andhigh-gloss baking enamels. Also called C.I. PigmentOrange 20.

cadmium red: A red nonbleeding inorganic pig-ment based on cadmium sulfide and sulfoselenide(Color Index Number 77202), having high lightfast-ness and good heat and alkali resistance. Used inPVC and polyolefin plastics, paints, and high-glossbaking enamels. Also called CP cadmium red, C.I.Pigment Red 108.

cadmium yellow: A yellow nonbleeding inorganicpigment based on cadmium sulfide and sulfoselenide(Color Index Number 77202), having high lightfast-ness and good heat and alkali resistance. Used inPVC and polyolefin plastics, paints, and high-glossbaking enamels.

carbon arc weatherometer: An apparatus foraccelerated indoor weatherability testing of mate-rials such as plastics. Equipped with one to twoenclosed or open-flame carbon arc lamps withborosilicate glass filters to simulate the sunlight andwith a water spraying device. The lamps used inthis apparatus have unnaturally high irradiance inthe short wavelength region, especially at 390 nm.As a result it produces less realistic degradation thanxenon arc apparatus. Most models allow controllingand monitoring temperature and humidity inside theapparatus as well as alternating dark and light cyclesof exposure.

carbon black: A black colloidal carbon filler madeby the partial combustion or thermal cracking ofnatural gas, oil, or another hydrocarbon. There areseveral types of carbon black depending on the start-ing material and the method of manufacture. Eachtype of carbon black comes in several grades. Carbonblack is widely used as a filler and pigment in rubbersand plastics. It reinforces, increases the resistance toUV light, reduces static charging.

cellulose acetate: Thermoplastic esters of cellu-lose with acetic acid. Have good toughness, gloss,clarity, processability, stiffness, hardness, and dielec-tric properties, but poor chemical, fire and waterresistance, and compressive strength. Processed byinjection and blow molding and extrusion. Used forappliance cases, steering wheels, pens, handles, con-tainers, eyeglass frames, brushes, and sheeting. Alsocalled CA.

cellulose acetate butyrate: Thermoplastic mixedesters of cellulose with acetic and butyric acids. Havegood toughness, gloss, clarity, processability, dimen-sional stability, weatherability, and dielectric prop-erties, but poor chemical, fire and water resistance,and compressive strength. Processed by injectionand blow molding and extrusion. Used for appliancecases, steering wheels, pens, handles, containers,eyeglass frames, brushes, and sheeting. Also calledCAB.

cellulose propionate: Thermoplastic esters of cel-lulose with propionic acid. Have good toughness,gloss, clarity, processability, dimensional stability,weatherability, and dielectric properties, but poorchemical, fire and water resistance, and compressivestrength. Processed by injection and blow moldingand extrusion. Used for appliance cases, steeringwheels, pens, handles, containers, eyeglass frames,brushes, and sheeting. Also called CP.

cellulosic plastics: Thermoplastic cellulose estersand ethers. Have good toughness, gloss, clarity,processability, and dielectric properties, but poorchemical, fire and water resistance, and compressivestrength. Processed by injection and blow moldingand extrusion. Used for appliance cases, steeringwheels, pens, handles, containers, eyeglass frames,brushes, and sheeting.

Chaetomium globosum: A species of commonmold belonging to the genus Chaetomium. Usedalone or in artificial mixtures with other fungi to pre-pare cultures for the testing of mildew resistance ofmaterials such as plastics, or fungicidal activity ofantimildew agents or fungicides.

chain scission: Breaking of the chain-like moleculeof a polymer as a result of chemical, photochem-ical, etc., reactions such as thermal degradation orphotolysis.

chalking: Formation of a dry, chalk-like, loosepowder on or just beneath the surface of a paint filmor plastic caused by the exudation of a compound-ing ingredient such as pigments, often as a resultof ingredient migration to the surface and surfacedegradation.

Glossary of Terms 411

channel black: Carbon black made by impinge-ment of a natural gas flame against a metal plateor channel iron, from which a deposit is scraped.Used as a reinforcing filler in rubbers. Also calledgas black.

checking: A defect on the surface of a topcoat paintmanifesting itself by slight breaks in the film so thatunderlying coats are visible. Some checks are sosmall that they are invisible without magnification.Also called surface checks.

chemical saturation: Absence of double or triplebonds in a chain organic molecule such as that ofmost polymers, usually between carbon atoms. Satu-ration makes the molecule less reactive and polymersless susceptible to degradation and cross-linking.Also called chemically saturated structure.

chemical unsaturation: Presence of double ortriple bonds in a chain organic molecule such asthat of some polymers, usually between carbonatoms. Unsaturation makes the molecule more reac-tive, especially in free-radical addition reactionssuch as addition polymerization, and polymers moresusceptible to degradation, cross-linking, andchemical modification. Also called polymer chainunsaturation.

chemically saturated structure: See chemicalsaturation.

chlorendic polyester: A chlorendic anhydride-based unsaturated polyester.

chlorinated polyvinyl chloride: Thermoplasticproduced by chlorination of PVC. Has increasedglass transition temperature, chemical and fire resis-tance, rigidity, tensile strength, and weatherabilitycompared to PVC. Processed by extrusion, injec-tion molding, casting, and calendering. Used forpipes, auto parts, waste disposal devices, and outdoorapplications. Also called CPVC.

chloroethyl alcohol(2-): See ethylene chloro-hydrin.

chlorohydrins: Halohydrins with chlorine as ahalogen atom. One of the most reactive of halohy-drins. Dichlorohydrins are used in the preparationof epichlorohydrins, important monomers in the

manufacture of epoxy resins. Most chlorohydrins arereactive colorless liquids, soluble in polar solventssuch as alcohols. Note: Chlorohydrins are a classof organic compounds, not to be mixed up with aspecific member of this class—l-chloropropane-2,3-diol, which sometimes called chlorohydrin.

chlorosulfonated polyethylene rubber: Thermo-setting elastomers containing 20–40% chlorine.Have good weatherability and heat and chemicalresistance. Used for hoses, tubes, sheets, footwearsoles, and inflatable boats.

chrome green: A green inorganic pigment consist-ing mainly of lead chromate and used in paints,rubbers, and plastics. Chrome green has good light-fastness, brightness, weatherability, and chemicalresistance.

Chromophtal green: A green organometallic pig-ment based on chromium phthalocyanine.

Chromophtal red: A red organometallic pigmentbased on chromium phthalocyanine.

Ci65 xenon arc weatherometer: See xenon arcweatherometer.

coated molybdate: See coated molybdate orangepigment.

coated molybdate orange pigment: Solid solu-tions of lead chromate, lead molybdate, and leadsulfate used as dark orange to light red inorganicpigments for plastics. When coated with silica thesepigments exhibit high hiding power, brightness,lightfastness, thermal stability, and resistance tobleeding. Also called coated molybdate.

cocatalyst: See accelerator.

color: The wavelength composition of light, specif-ically of the light reflected or emitted by the materialand its visual appearance (red, blue, etc.).Also calledhue, tint, coloration. Color stability is quantified andreported as �E.

color change: See discoloration.

color concentrate let down: Reducing the inten-sity or depth of the color of a concentrated colored

412 The Effects of UV Light and Weather on Plastics and Elastomers

pigment dispersion (or paste) in a vehicle (water,binder, or solvent) by the addition of a white, orsometimes colorless, pigment.

color difference: The square root of the sum ofthe squares of the chromaticity difference and thelightness difference. Also called �E, �E colorchange.

color masking agent: See masking filler.

coloration: See color.

colorimeter: An optical instrument for determiningor matching colors. The sample’s color is matchedvisually with the color resulting from the superpo-sition of the light that passes through three primarycolor filters adjusted to transmit a varying amount oflight. Or, an optical instrument for determining theconcentration of a colored solution by comparingits absorbance in a certain wavelength region withthat of a standard solution with known concentration.Also called Hunter Colorimeter.

composite spore suspension: A mixture of sporesof different fungus species suspended in culturemedia and used for testing the mildew resistance ofmaterials such as paints and plastics and the activityof antimildew agents and fungicides.

concentration units: The units for measuring thecontent of a distinct material or substance in amedium other than this material or substance, such asa solvent. Note: The concentration units are usuallyexpressed in the units of mass or volume of substanceper one unit of mass or volume of medium. When theunits of the substance and the medium are the same,the percentage is often used.

conditioning: Process of bringing the material orapparatus to a certain condition (e.g., moisture con-tent or temperature) prior to further processing,treatment, etc. Also called conditioning cycle.

conditioning cycle: See conditioning.

conventional aging: Prolonged exposure of mate-rials such as plastics to natural or artificial envi-ronmental conditions to produce degradation as in

weatherability testing, without accelerating the pro-cess by using above normal temperature, irradiation,etc.

conventional aging with spray: Prolonged expo-sure of materials such as plastics to natural orartificial environmental conditions, including wateror salt spray, to produce degradation as in weather-ability testing, without accelerating the process byusing above normal temperature, irradiation, etc.

covulcanization: Simultaneous vulcanization of ablend of two or more different rubbers to enhancetheir individual properties such as ozone resi-stance. Rubbers are often modified to improvecovulcanization.

CP: See cellulose propionate.

CP cadmium red: See cadmium red.

CPVC: See chlorinated polyvinyl chloride.

cracking: Appearance of external and/or internalcracks in the material as a result of stress that exceedsthe strength of the material. The stress can be exter-nal and/or internal and can be caused by a variety ofadverse conditions: structural defects, impact, aging,corrosion, etc., or a combination of these conditions.Also called cracks. See also processing defects.

cracks: See cracking.

crazes: See crazing.

crazing: Appearance of thin cracks on the surface ofthe material or, sometimes, minute frost-like internalcracks, as a result of stress that exceeds the strengthof the material. The stress can be caused by a varietyof adverse conditions: impact, temperature changes,degradation, etc. Also called crazes.

cross-linked polyethylene: Polyethylene thermo-plastics that are partially photochemically or chem-ically cross-linked. Have improved tensile strength,dielectric properties, and impact strength at low andelevated temperatures.

cross-linking: Reaction resulting in the forma-tion of covalent bonds between chain-like polymer

Glossary of Terms 413

molecules or between polymer molecules and low-molecular compounds such as carbon black fillers.As a result of cross-linking polymers, such as ther-mosetting resins, may become hard and infusible.Cross-linking is induced by heat, UV or electron-beam radiation, oxidation, etc. Cross-linking can beachieved either between polymer molecules aloneas in unsaturated polyesters or with the help of mul-tifunctional cross-linking agents such as diaminesthat react with functional side groups of the poly-mers. Cross-linking can be catalyzed by the presenceof transition metal complexes, thiols, and othercompounds.

crystal polystyrene: See general purposepolystyrene.

CTFE: See polychlorotrifluoroethylene.

CTH-Glas Trac: Asun-tracking, automotive glass-covered cabinet for accelerated outdoor weatheringof automotive interior materials. The air temperatureinside the cabinet is controlled and usually main-tained at 70◦C during daylight hours and 38°C duringnight. The relative humidity during night is con-trolled and usually maintained at 75%. Produced byHeraeus DSET Laboratories, Inc., Phoenix,Arizona.

cycle time: See processing time.

cyclic compounds: A broad class of organic com-pounds consisting of carbon rings that are saturated,partially unsaturated, or aromatic, in which somecarbon atoms may be replaced by other atoms suchas oxygen, sulfur, and nitrogen.

D

DAP: See diallyl phthalate resins.

dark cycle: In weathering and light exposure testingthat simulates outdoor environments, a period whenthe specimen is not irradiated, which alternates withthe period of irradiation.

dart drop impact: See falling weight impactenergy.

dart drop impact energy: See falling weightimpact energy.

dart drop impact strength: See falling weightimpact energy.

decoloration: Complete or partial loss of color ofthe material as a result of degradation or removalof colored substances present in it. Also calleddecoloring.

decoloring: See decoloration.

defects: See processing defects.

deflection temperature under load: See heatdeflection temperature.

degradation: Loss or undesirable change in theproperties, such as color, of a material as a resultof aging, chemical reaction, wear, exposure, etc. Seealso stability.

�E: See color difference.

�E color change: See color difference.

dew cycle: In light and water exposure testing thatsimulates outdoor environments, a period when thespecimen is exposed to condensation instead of radi-ation, which alternates with the period of irradiation.Condensation is produced by exposing one surfaceof the specimen to a heated, saturated mixture of airand water vapor, while cooling the opposite surface.

diallyl phthalate resins: Thermosets supplied asdiallyl phthalate prepolymers or monomers. Havehigh chemical, heat and water resistance, dimen-sional stability, and strength. Shrink during peroxidecuring. Processed by injection, compression, andtransfer molding. Used in glass-reinforced tubing,auto parts, and electrical components. Also calledDAP.

dihydric alcohols: See glycols.

dihydroxy alcohols: See glycols.

DIN 6167: A German Standard Institute standardspecifying conditions for determination of the yel-lowness (yellowness index) of near-white or near-colorless materials such as plastics and nonmetalliccoatings.

414 The Effects of UV Light and Weather on Plastics and Elastomers

DIN 50031: A German Standards Institute standardspecifying conditions for salt spray testing of anti-corrosive properties of materials such as metallicand nonmetallic coatings on metal substrates. Thespecimens are exposed to a fine spray of a NaCl(5 g/100 mL), acetic acid-NaCl (pH 3.1–3.4), orCuCu12-acetic acid-NaCl (CASS lest, pH 3.1–3.4)solution at about 35◦C in a special chamber for96 hours. The results are assessed by measuring therate of corrosion (i.e., weight loss per unit area of thetest panel).

DIN 53231: A German Standards Institute standardspecifying conditions for artificial weathering (withwetting) and aging (without wetting) of coatings byexposure to filtered xenon-arc lamp irradiation. Thespecimens are exposed to 550 W/m3 average hourlyirradiance at 290–800 nm wavelength with (method1) or without (method 2) wetting and filtering of thelight through a 3-mm thick window glass at 40–60%relative humidity. For method 1, rain is simulatedby immersion or spraying and condensation is simu-lated by spraying the back of the test panels with coldwater. The wetting may be continuous or periodicwith 102- or 17-minute dry periods. The degradationof the specimens is assessed visually and by measur-ing the changes in color, mechanical (e.g., impact andtensile strength), and other properties. Also calledDIN 53231 method I, DIN 53231 method 2.

DIN 53231 method 1: See DIN 53231.

DIN 53231 method 2: See DIN 53231.

DIN 53387: A German Standards Institute stan-dard specifying conditions for artificial weathering(with wetting) and aging (without wetting) of plas-tics and elastomers by exposure to filtered xenon-arclamp irradiation. The specimens are exposed to550 W/m3 average hourly irradiance at 290–800 nmwavelength with (method 1) or without (method 2)wetting and filtering of the light through a 3-mmthick window glass at 40–60% relative humidity.For method 1, rain is simulated by immersion orspraying and condensation is simulated by spray-ing the back of the test panels with cold water.The wetting may be continuous or periodic with102- or 17-minute dry periods. The degradation ofthe specimens assessed visually and by measuring

the changes in color, mechanical (e.g., impact andtensile strength), and other properties. Also calledDIN 53387 method 1, DIN 53387 method 2.

DIN 53387 method 1: See DIN 53387.

DIN 53387 method 2: See DIN 53387.

DIN 53388: A German Standards Institute standardspecifying conditions for the testing of resistance todegradation of plastics and elastomers exposed towindow glass-filtered daylight. Also called ISO 877,DIN 53388 scale.

DIN 53388 scale: See DIN 53388.

DIN 53453: A German Standards Institute standardspecifying conditions for the flexural impact testingof molded or laminated plastics. The bar specimensare either unnotched or notched on one side, mountedon a two-point support, and struck in the middle (onthe unnotched side for notched specimens) by a ham-mer of the pendulum impact machine. The impactstrength of the specimen is calculated relative to thecross-sectional area of the specimen as the energyrequired to break the specimen equal lo the differencebetween the energy in the pendulum at the instant ofimpact and the energy remaining after complete frac-ture of the specimen. Also called DIN 53453 impacttest.

DIN 53453 impact test: See DIN 53453.

DIN 54001: A German Standards Institute standardspecifying conditions for the preparation and use ofgray scale for assessing the change in color dur-ing accelerated testing of colorfastness of dyed andprinted textiles. Also called ISO 105-A02.

DIN 54003: German Standards Institute standardspecifying conditions for the accelerated testing ofcolorfastness of interior materials in motor vehiclesto light by irradiation with a glass-filtered xenon-arc lamp. Also called DIN 54003 (FAKRA), ISO105-B06.

DIN 54003 (FAKRA): See DIN 54003.

DIN 54004: A German Standards Institute standardspecifying conditions for the accelerated testing of

Glossary of Terms 415

colorfastness of dyed and printed textiles to light byirradiation with a xenon-arc fading lamp.Also calledISO 105-B04.

DIN 54071: A German Standards Institute standardspecifying conditions for the accelerated testing ofcolorfastness of dyed and printed textiles to weatherby irradiation with a xenon-arc lamp. Also calledISO 105-B04.

discoloration: A change in color due to chemical orphysical changes in the material. Also called colorchange.

disperse dyes: Nonionic dyes insoluble in waterand used mainly as fine aqueous dispersions indying acetate, polyester, and polyamide fibers. Alarge subclass of disperse dyes comprises low-molecular-weight aromatic azo compounds withamino, hydroxy, and alkoxy groups that fix on fibersby forming Van der Waals and hydrogen bonds.

displacement: Process of removing one object(e.g., a medium in an apparatus) or its part andreplacing it with another. Also called displacementcycle.

displacement cycle: See displacement.

double carbon arc weatherometer: An apparatusfor accelerated indoor testing of weatherability ofmaterials such as plastics. Equipped with a carbonarc lamp having a combination of neutral solid andcored electrodes enclosed in a borosilicate glass fil-ter to simulate sunlight and with a water sprayingdevice. Most models allow controlling and monitor-ing temperature and humidity inside the apparatus aswell as alternating dark and light cycles of exposure.

drop weight impact: See falling weight impactenergy.

drop weight impact energy: See falling weightimpact energy.

drop weight impact strength: See falling weightimpact energy.

DSET: Heraeus DSETLaboratories, Inc.APhoenix,Arizona, company specializing in conventional

and accelerated weatherability testing services andequipment.

E

ECTFE: See ethylene-chlorotrifluoroethylenecopolymer.

elongation: The increase in gauge length of a spec-imen in tension, measured at or after the fracture,depending on the viscoelastic properties of the mate-rial. Note: Elongation is usually expressed as apercentage of the original gauge length. Also calledtensile elongation, elongation at break, ultimate elon-gation, breaking elongation, elongation at rupture.See also tensile strain.

elongation at break: See elongation.

elongation at rupture: See elongation.

EMAC: See ethylene-methyl acrylate copolymer.

embrittlement: A reduction or low of ductility ortoughness in materials such as plastics resulting fromchemical or physical damage.

EMMA: See equatorial mount with mirrors foracceleration.

EMMAQUA: See equatorial mount with mirrorsfor acceleration plus water spray.

enclosed carbon arc: See enclosed carbon arclamp.

enclosed carbon arc lamp: Alight source for accel-erated indoor weatherability testing of materials suchas plastics that consists of a carbon arc enclosed ina borosilicate glass filter for short wavelengths tosimulate sunlight. The enclosed carbon arc lampshave unnaturally high irradiance in the short wave-length region, especially at 390 nm. As a result theyproduce less realistic degradation than xenon arclamps. Also called enclosed carbon arc.

energy quencher: A low-molecular weight organiccompound such as a polycyclic aromatic com-pound that retards ionizing radiation-induced poly-mer degradation by scavenging or trapping part of

416 The Effects of UV Light and Weather on Plastics and Elastomers

excited-state energy of the polymer without under-going significant chemical change due to the highlyefficient decay of its own excited states. Also calledenergy quencher additives, energy scavenger.

energy quencher additives: See energy quencher.

energy scavenger: See energy quencher.

EPDM: See EPDM rubber.

EPDM rubber: Sulfur-vulcanizable thermosettingelastomers produced from ethylene, propylene, anda small amount of a nonconjugated diene such ashexadiene. Have good weatherability and chemi-cal and heat resistance. Used as impact modifiersand for weather stripping, auto parts, cable insula-tion, conveyor belts, hoses, and tubing. Also calledEPDM.

epoxides: Organic compounds containing three-membered cyclic group(s) in which two carbonatoms are linked with an oxygen atom as in an ether.This group is called an epoxy group and is quite reac-tive, allowing the use of epoxides as intermediatesin the preparation of certain fluorocarbons and cellu-lose derivatives, and as monomers in the preparationof epoxy resins. Also called epoxy compounds.

epoxies: See epoxy resins.

epoxy compounds: See epoxides.

epoxy resins: Thermosetting polyethers containingcross-linkable glycidyl groups. Usually prepared bythe polymerization of bisphenol A and epichloro-hydrin or reacting phenolic novolaks with epichloro-hydrin. Can be made unsaturated by acrylation.Unmodified varieties are cured at room or ele-vated temperatures with polyamines or anhydrides.Bisphenol A epoxy resins have excellent adhesionand very low shrinkage during curing. Cured novolakepoxies have good UVstability and dielectric proper-ties. Cured acrylated epoxies have high strength andchemical resistance. Processed by molding, casting,coating, and lamination. Used as protective coat-ings, adhesives, potting compounds, and binders inlaminates and composites. Also called epoxies.

epoxyethane: See ethylene oxide.

EPR: See ethylene-propene rubber.

equatorial mount with mirrors: See equatorialmount with mirrors for acceleration.

equatorial mount with mirrors and waterspray: See equatorial mount with mirrors for accel-eration plus water spray.

equatorial mount with mirrors for acceleration:An accelerated outdoor weathering test methoddeveloped by Heraeus DEST Laboratories, Inc., forexterior materials with equatorial mount of specimenpanels and reflector mirrors to increase solar irradia-tion. The equatorial mount means that the specimenpanels are continuously maintained in the positionfacing and normal to the sun. The mirrors followthe sun for maximum reflection.Also called EMMA,equatorial mount with mirrors.

equatorial mount with mirrors for accelerationplus water spray: An accelerated outdoor weath-ering test method developed by Heraeus DESTLaboratories, Inc., for exterior materials with equa-torial mount of specimen panels and reflector mirrorsto increase solar irradiation and water spray to simu-late humid climate. The equatorial mount means thatthe specimen panels are continuously maintained inthe position facing and normal to the sun. The mir-rors follow the sun for maximum reflection. Alsocalled EMMAQUA, equatorial mount with mirrorsand water spray.

ETFE: See ethylene-tetrafluoroethylene copolymer.

ethanediol(1,2-): See ethylene glycol.

ethers: A class of organic compounds in whichan oxygen atom is interposed between two carbonatoms in a chain or ring. Ethers are derived mainly bythe catalytic of olefins. The lower molecular weightether are dangerous fire and explosion hazards. Note:Major types of ethers include aliphatic, cyclic, andpolymeric ethers.

ethylene-acrylic rubber: Copolymers of ethyleneand acrylic esters. Have good toughness, low tem-perature properties, and resistance to heat, oil, andwater. Used in auto and heavy equipment parts.

Glossary of Terms 417

ethylene alcohol: See ethylene glycol.

ethylene chlorohydrin (C2H5ClO): Ethylenechlorohydrin, ClCH2CH2OH, is a colorless liquidthat is easily soluble in most organic liquids andwater. It has an autoignition temperature of 450◦C(797◦F) and is a moderate fire hazard. Derived bythe reaction of hydrochlorous acid with ethylene. Itis a strong irritant, deadly via inhalation, skin absorp-tion, etc., with a TLV of 1 ppm in air. Penetratesthrough rubber gloves. Used as a solvent for cellulosederivatives, intermediate in organic synthesis (e.g.,for ethylene oxide), and sprouting activator. Note:Hydrolysis of ethylene oxide during sterilization canresult in the formation of ethylene chlorohydrin andits residual presence in sterilized goods. Also called2-chloroethyl alcohol. glycol chlorohydrin. See alsochemical sterilization agent hydrolysis products.

ethylene copolymers: See ethylene polymers.

ethylene-methyl acrylate copolymer: Thermo-plastic copolymers of ethylene with <40% methylacrylate. Have good dielectric properties, tough-ness, thermal stability, stress crack resistance, andcompatibility with other polyolefins. Transparencydecreases with increasing content of acrylate. Pro-cessed by blow film extrusion and blow and injectionmolding. Used in heat-sealable films, disposablegloves, and packaging. Some grades are FDA-approved for food packaging. Also called EMAC.

ethylene polymers: Ethylene polymers includeethylene homopolymers and copolymers with otherunsaturated monomers, most importantly olefinssuch as propylene and polar substances such as vinylacetate.The properties and uses of ethylene polymersdepend on the molecular structure and weight. Alsocalled ethylene copolymers.

ethylene-propene rubber: Stereospecific copoly-mers of ethylene with propylene. Used is impactmodifiers for plastics. Also called EPR.

ethylene-tetrafluoroethylene copolymer: Thermo-plastic alternating copolymer of ethylene andtetrafluoroethylene. Has good impact strength, abra-sion and chemical resistance, weatherability, anddielectric properties. Processed by molding, extru-sion, and powder coating. Used in tubing, cables,

pump parts, and tower packing in a wide temperaturerange. Also called ETFE.

ethylene-vinyl alcohol copolymer: Thermo-plastics prepared by hydrolysis of ethylene-vinylacetate polymers. Have good barrier properties,mechanical strength gloss elasticity, weatherability,clarity, and abrasion resistance. Barrier propertiesand processability improve with increasing contentof ethylene due to lower absorption of moisture.Processed by extrusion, coating, blow and film mold-ing, and thermoforming. Used as packaging filmsand container liners. Also called EVOH.

EVOH: See ethylene-vinyl alcohol copolymer.

extenders: Relatively inexpensive resin, plasti-cizer, or filler such as carbonate used to reduce costand/or to improve processing of plastics, rubbers, ornonmetallic coatings.

exterior rutile TiO2: See exterior rutile titaniumdioxide.

exterior rutile titanium dioxide: Special grades ofrutile titanium dioxide with increased weatherabilitythat are used as a white or opacifying pigment in awide range of exterior materials including coatingsand plastics. Exterior grades of rutile are often chem-ically modified (e.g., with chromia) to increase theirdurability. Also called exterior rutile TiO2.

F

F40 UVB: See QFS-40 lamp.

fade-o-meter: See fadeometer.

fadeometer: A light exposure apparatus for accel-erated testing of lightfastness of colored materialssuch as plastics or textiles. The apparatus is equippedwith a light source that simulates sunlight but pro-vides a more intense irradiation. Light sources usedare carbon- or xenon-arc lamps. Among the manu-facturers of fadeometers is Atlas Electric DevicesCo., Chicago, Illinois.Also called fade-o-meter, atlasfadeometer.

falling dart impact: See falling weight impactenergy.

418 The Effects of UV Light and Weather on Plastics and Elastomers

falling dart impact energy: See falling weightimpact energy.

falling dart impact strength: See falling weightimpact energy.

falling sand abrasion test: A test for determiningabrasion resistance of coatings by the amount ofabrasive sand required to wear though a unit thick-ness of the coating. When sand falls against it ata specified angle from a specified height though aguide tube. Also called falling sand test method.

falling sand test method: See falling sand abrasiontest.

falling weight impact: See falling weight impactenergy.

falling weight impact energy: The mean energyof a free-falling dart or weight (tup) that will cause50% failures after 50 tests to a directly or indirectlystricken specimen. The energy is calculated by multi-plying dart mass, gravitational acceleration, and dropheight. Also called falling weight impact strength,falling weight impact, falling dart impact energy,falling dart impact strength, falling dart impact, dartdrop impact energy, dart drop impact strength.

falling weight impact strength: See falling weightimpact energy.

FEP: See fluorinated ethylene-propylene copolymer.

Fiberglass: Material made from extremely fineglass fibers.

fireproofing agent: See flame retardant.

five-membered heterocyclic compounds: A classof heterocyclic compounds containing rings thatconsist of live atoms.

five-membered heterocyclic nitrogen compounds:A class of heterocyclic compounds containingrings that consist of five atoms, some of which arenitrogen.

five-membered heterocyclic oxygen compounds:A class of heterocyclic compounds containing ringsthat consist of five atoms, some of which are oxygen.

flame retardant: A substance that reduce theflammability of materials such as plastics or textilesin which it is incorporated. There are inorganic flameretardants such as antimony trioxide (Sb2O3) andorganic flame retardants such as brominated polyols,The mechanisms of flame retardation vary dependingon the nature of the material and flame retardant. Forexample, some flame retardants yield a substantialvolume of coke on burning, which prevents oxy-gen from reaching inside the material and blocksfurther combustion. Also called fireproofing agent,flame retardant chemical additives, ignition resistantchemical additives.

flame retardant chemical additives: See flameretardant.

flaw: See processing defects.

flexural properties: Properties describing the reac-tion of physical systems to flexural stress and strain.Also called bending properties.

flexural strength: The maximum stress in theextreme fiber of a specimen loaded to failure inbending. Note: Flexural strength is calculated as afunction of load, support span, and specimen geo-metry. Also called modulus of rupture in bending,modulus of rupture, bending strength.

flexural stress: The maximum stress in the extremefiber of a specimen in bending. Note: Flexural stressis calculated as a function of load at a given strainor at failure, support span, and specimen geometry.Also called bending stress.

fluorescent sunlamp with dew: See fluorescent UVlamp-condensation apparatus.

fluorescent UVlamp-condensation apparatus: Anapparatus for accelerated indoor weathering of mate-rials such as plastics equipped with a fluorescentUV-A lamp like UVA-340 that produces an energyspectrum with a peak emission at 340 nm and sim-ulates closely the short wavelength region of solarradiation, or with a fluorescent UV-B lamp like

Glossary of Terms 419

UVB-313 with a peak emission at 313 nm that pro-vides a significantly higher UV radiation output forfaster testing. The apparatus is also equipped witha condensation unit that supplies water vapor. Thevapor condenses on the surface of the specimenwhich is cooled from behind to simulate the dew.Among the manufacturers of fluorescent UV lamp-condensation apparatus is Atlas Electric DevicesCo., Chicago, Illinois, and The Q-Panel Co., Cleve-land, Ohio (QUV accelerated weathering tester).Also called fluorescent sunlamp with dew, fluores-cent UV-condensation apparatus. Atlas UV-CON,UV-CON, QUV accelerated weathering tester.

fluorescent UV-condensation apparatus: Seefluorescent UV lamp-condensation apparatus.

fluorinated ethylene-propylene copolymer: Ther-moplastic copolymer of tetrafluoroethylene andhexafluoropropylene. Has decreased tensile strengthand wear and creep resistance, but good weatherabil-ity, dielectric properties, fire and chemical resistance,and friction. Decomposes above 204◦C (400◦F),releasing toxic products. Processed by molding,extrusion, and powder coating. Used in chemicalapparatus liners, pipes, containers, bearings, films,comings, and cables. Also called FEP.

fluoro rubber: See fluoroelastomers.

fluoroelastomers: Fluorine-containing syntheticrubber with good chemical and heat resistance. Usedin underhood applications such as fuel lines, oil andcoolant seals, and fuel pumps, and as a flow additivefor polyolefins. Also called fluoro rubber.

fluoroplastics: See fluoropolymers.

fluoropolymers: Polymers prepared from unsatu-rated fluorine-containing hydrocarbons. Have goodchemical resistance, weatherability, thermal stabil-ity, antiadhesive properties, and low friction andflammability, but low creep resistance and strengthand poor processibility. The properties vary withthe fluorine content. Processed by extrusion andmolding. Used as liners in chemical apparatus, inbearings, films, coatings, and containers. Also calledfluoroplastics.

fluorosilicones: Polymers with chains of alternat-ing silicon and oxygen atoms and trifluoropropylpendant groups. Most are rubbers.

FMQ: See methylfluorosilicones.

Fourier-transform infrared spectrometry: Aspectroscopic technique in which all wavelengths inthe infrared region (750–1 × 106 nm) are simultane-ously used to irradiate the sample for a short periodof time, and the absorption spectrum is found bymathematical manipulation of the Fourier transform(a periodic function) obtained. Also called FTIRanalysis.

FS-40: See QFS-40 lamp.

FS-40 (UV-B) lamps: See QFS-40 lamp.

FS-40 lamp: See QFS-40 lamp.

FTIR analysis: See Fourier-transform infraredspectrometry.

fungus resistance: See mildew resistance.

furnace black: The most common type of carbonblack made by burning vaporized heavy oil fractionsin a furnace with 50% of the air required for com-plete combustion. It comes in high abrasion, fastextrusion, high modulus, general purpose, semire-inforcing, conducting, high elongation, reinforcing,and fast-extruding grades among others. Furnaceblack is widely used as a filler and pigment in rubbersand plastics. It reinforces, increases the resistance toUV light, and reduces static charging.

G

gas black: See channel black.

general purpose polystyrene: General purposepolystyrene is an amorphous thermoplastic preparedby homopolymerization of styrene. It has good ten-sile and flexural strengths, high light transmission,and adequate resistance to water, detergents, andinorganic chemicals. It is attached by hydrocarbonsand has a relatively low impact resistance. Pro-cessed by injection molding and foam extrusion.Used to manufacture containers, health care items

420 The Effects of UV Light and Weather on Plastics and Elastomers

such as pipettes, kitchen and bathroom housewares,stereo and camera parts, and foam sheets for foodpackaging. Also called crystal polystyrene.

gloss: The ratio of the light specularly reflected froma surface of material such as plastics or nonmetalliccoatings to the total light reflected. The gloss is mea-sured at a specified angle of incidence of light (e.g.,60◦). It usually decreases as a result of weathering.

glycol-modified polycyclohexylenedimethyleneterephthalate: Thermoplastic polyester preparedfrom glycol, cyclohexylenedimethanol, and tereph-thalic acid. Has good impact strength and othermechanical properties, chemical resistance, and clar-ity. Processed by injection molding and extrusion.Can be blended with polycarbonate. Also calledPCTG.

glycols: Aliphatic alcohols with two hydroxygroups attached to a carbon chain. Can be producedby the oxidation of alkenes followed by hydration.Also called dihydric alcohols, dihydroxy alcohols.

gray scale rating: Evaluating light-induced changesin the color of materials such as plastics, rubbers, andnonmetallic coatings by comparing to a gray scale.A gray scale is a series of achromatic tones (usuallyten) having varying proportions of white and black,to give a full range of grays between white and black.

H

halogen compounds: A class of organic com-pounds containing halogen atoms such as chlorine.A simple example is halocarbons, but many othersubclasses with various functional groups and ofdifferent molecular structure exist as well.

halohydrins: Halogen compounds that contain ahalogen atom(s) and a hydroxy (OH) group(s)attached to a carbon chain or ring. Can be preparedby the reaction of halogens with alkenes in the pres-ence of water or by the reaction of halogens withtriols. Halohydrins can be easily dehydrochlorinatedin the presence of a base to give an epoxy compound.

HALS: See hindered amine tight stabilizer.

hard clays: Sedimentary rocks composed mainly offine clay mineral material without natural plasticity,or any compacted or indurated clay.

haze: The percentage of transmitted light which, inpassing through a plastic specimen, deviates fromthe incident beam via forward scattering by morethat 2.5◦ on average (ASTM D883).

HDPE: See high density polyethylene.

HDT: See heat deflection temperature.

heat deflection point: See heat deflectiontemperature.

heat deflection temperature: The temperature atwhich a material specimen (standard bar) is deflectedby a certain degree under a specified load.Also calledheat distortion temperature, heat distortion point,heat deflection point, deflection temperature underload, tensile heat distortion temperature, HDT.

heat distortion point: See heat deflectiontemperature.

heat distortion temperature: See heat deflectiontemperature.

heterocyclic compounds: A class of cyclic com-pounds containing rings with some carbon atomsreplaced by other atoms such as oxygen, sulfur, andnitrogen.

hiding power: The capacity of a coating materialsuch as paint and, by extension, of the pigment in itto render invisible or cover up a surface on which itis applied as a film. For paints, hiding power is oftenexpressed in gallons per square foot. Also calledopacity.

high density polyethylene: A linear polyethylenewith density 0.94–0.97 g/cm3. Has good toughnessat low temperatures, chemical resistance, and dielec-tric properties and high softening temperature, butpoor weatherability. Processed by extrusion, blowand injection molding, and powder coating. Usedin houseware, containers, food packaging, liners,cable insulation, pipes, bottles, and toys. Also calledHDPE.

Glossary of Terms 421

high impact polystyrene: See impact polystyrene.

high molecular weight low density polyethylene:Thermoplastic with improved abrasion and stresscrack resistance and impact strength, but poor pro-cessibility and reduced tensile strength. Also calledHMWLDPE.

hindered amine light stabilizer: Amines, such aspiperidine derivatives, with a bulky, sterically hin-dered molecular structure. These light stabilizersphoto-oxidize readily to nitroxyl radicals that neu-tralize, via recombination, alkyl radicals formedduring the photodegradation of polymers such aspolyolefins and therefore retard this process. Alsocalled HALS.

HIPS: See impact polystyrene.

HMWLDPE: See high molecular weight lawdensity polyethylene.

HPUV: A test used to simulate the effect of fluo-rescent lighting and filtered sunlight. The HPUVtest uses two lamps simultaneously, a cool whitefluorescent lamp and a filtered sunlamp.

hue: See color.

Hunter color meter: See colorimeter.

hydrophilic starch surface: See hydrophilicsurface.

hydrophilic surface: The surface of a hydrophilicsubstance that has a strong ability to bind, adsorb, orabsorb water; a surface that is readily wettable withwater. Hydrophilic substances include carbohydratessuch as starch.Also called hydrophilic starch surface.

hydroxy compounds: A broad class of organiccompounds that contain a hydroxy (OH) group(s)that is not part of another functional groups such ascarboxylic groups. Also called hydroxyl-containingcompounds.

hydroxybenzophenone: See 2-hydroxybenzc-phenone.

hydroxybenzophenone(2-): An aromatic ketone,C6H5COC6H4OH, used as a UV absorber in plastics.

A solid at room temperature, insoluble in waterbut soluble in alcohols. Also called hydroxybenzo-phenone.

hydroxyl-containing compounds: See hydroxycompounds.

I

ignition resistant chemical additives: See flameretardant.

impact energy: The energy required to break aspecimen, equal to the difference between the energyin the striking member of the impact apparatus at theinstant of impact and the energy remaining after com-plete fracture of the specimen. Also called impactstrength. See also ASTM D256, ASTM D3763.

impact polystyrene: Impact polystyrene is athermoplastic produced by polymerizing styrene dis-solved in butadiene rubber. Impact polystyrene hasgood dimensional stability, high rigidity, and goodlow temperature impact strength, but poor barrierproperties, grease resistance, and heat resistance.Processed by extrusion, injection molding, ther-moforming, and structural foam molding. Used infood packaging, kitchen housewares, toys, smallappliances personal care items, and audio products.Also called IPS, high impact polystyrene, HIPS,impact PS.

impact property tests: Names and designations ofthe methods for the impact testing of materials. Alsocalled impact tests. See also impact toughness.

impact PS: See impact polystyrene.

impact strength: The energy required to break aspecimen, equal to the difference between the energyin the striking member of the impact apparatus at theinstant of impact with the specimen and the energyremaining after complete fracture of the specimen.

impact strength: See impact energy.

impact tests: See impact property tests.

impact toughness: The property of a material indi-cating its ability to absorb energy of a high-speed

422 The Effects of UV Light and Weather on Plastics and Elastomers

impact by plastic deformation rather than crack orfracture. See also impact property tests.

inoculum: A small amount of medium containingmicroorganisms from a pure culture which is used tostart a new culture or to introduce microorganismsinto a specimen.

ionomers: Thermoplastics containing a relativelysmall amount of pendant ionized acid groups. Havegood flexibility and impact strength in a wide tem-perature range, puncture and chemical resistance,adhesion, and dielectric properties, but poor weather-ability, fire resistance, and thermal stability. Pro-cessed by injection, blow and rotational molding,blown film extrusion, and extrusion coating. Usedin food packaging, auto bumpers, sporting goods,and foam sheets.

IPS: See impact polystyrene.

iron oxide: A dark red powder, Fe2O3, widely used,especially as a heat-stable, anticorrosive pigment incoatings. Produced synthetically or from iron ores.

irradience: The amount of radiant power per unitarea of irradiated surface at a point in time.Ameasureof radiation exposure, it is often expressed in the unitsof watt per square meter (W/m2). Also called radiantflux density.

ISO 105-A02: See DIN 54001.

ISO 105-B02: See DIN 54004.

ISO 105-B04: See DIN 54071.

ISO 105-B06: See DIN 54003.

ISO 877: See DIN 53388.

ISO 4665 part 2: An international standard describ-ing the methods of outdoor exposure of vulcanizedrubber to assess its resistance to weathering andozone cracking under atmospheric conditions withor without a glass cover. The specimens are mountedon a sloped rack facing the equator in direct sun,normally without backing, for up to 6 years. Strainis applied for the ozone cracking resistance test.Solar radiation is measured by a photoreceptor or by

Blue Wool Standards. Other climatic conditions arerecorded as well. The deterioration of the specimenis assessed visually and by measuring the change incolor or other properties.

ISO 4665 part 3: An international standard describ-ing the methods of exposure to the artificial daylightfrom a xenon-arc lamp during accelerated light resis-tance testing of vulcanized rubber. The lamp isequipped with a filter to reduce short wavelengthemission and is installed in an enclosure. The test iscarried out at a black panel temperature about 55◦Cand relative humidity of about 65% without waterspray or with intermittent water spray. The deterio-ration of the specimen is assessed visually and bymeasuring the change in color or other properties.Radiation dosage is determined by a photoreceptor,Blue Wool Standards (ISO 105-B01) and the grayscale (ISO 105-A02), or other physical standards.

ISO 4892: An international standard describing themethods of exposure to artificial light from a xenon-arc, enclosed carbon-arc, or open-flame carbon-arclamp during accelerated light resistance testing ofplastics and textiles. The lamp is equipped with afilter to reduce short wavelength emission and isinstalled in an enclosure. The test is carried out ata black panel temperature about 45–63◦C and rela-tive humidity of about 35–90% without water sprayor with intermittent water spray. The deteriorationof the specimen is assessed visually and by measur-ing the change in color or other properties. Radiationdosage is determined by a photoreceptor. Blue WoolStandards (ISO 105-B01) and the gray scale (ISO105-A02), or other physical standards. Also calledISO 4892/2 method A, ISO 4892/2 method B.

ISO 4892/2 method A: See ISO 4892.

ISO 4892/2 method B: See ISO 4892.

isophthalate polyester: An unsaturated polyesterbased on isophthalic acid.

Izod: See Izod impact energy.

Izod impact: See Izod impact energy.

Izod impact energy: The energy required to break aspecimen, equal to the difference between the energy

Glossary of Terms 423

in the striking member of the Izod-type impactapparatus at the instant of impact and the energyremaining after complete fracture of the specimen.Also called Izod impact, Izod impact strength, Izod.

Izod impact strength: See Izod impact energy.

J

J: See joule.

joule: A unit of energy in the SI system that is equalto the work done when the point of application of aforce of one newton (N) is displaced through distanceof one meter (m) in the direction of the force. Thedimension of joule is N m. Also called J.

K

kinetic strip test: An ozone resistance test for rub-bers that involves a strip-shaped specimen stretchedto 23% and relaxed to 0 at a rate of 30 cycles perminute, while subjected to ozone attack in the testchamber. The results of the test are reported with twodigits separated with a virgule. The number beforethe virgule indicates the number of quarters of thetest strip which showed the cracks. The number afterthe virgule indicates the size of the cracks in lengthperpendicular to the length of the strip.

L

langley: A unit of total solar radiation that is equalto one calorie of heat energy per square centimeterof irradiated surface (1 gram calorie/cm2/minute).

LCP: See liquid crystal polymers.

LDPE: See low density polyethylene.

light cycle: In weathering and light exposure testingthat simulates outdoor environments, a period whenthe specimen is irradiated, which alternates with theperiod of darkness.

light stability: See lightfastness.

light transmission: See transmittance.

lightfastness: The resistance of a material to deteri-oration as evident by a change in color, performance,mechanical properties, etc., as a result of exposure tosunlight or a artificial light source. Also called lightstability.

linear low density polyethylene: Linear poly-ethylenes with density 0.91–0.94 g/cm3. Has bettertensile, tear, and impact strength and crack resistanceproperties, but poorer haze and gloss than branchedlow density polyethylene. Processed by extrusionat increased pressure and higher melt temperaturescompared to branched low density polyethylene,and by molding. Used to manufacture films, sheets,pipes, electrical insulation, liners, bags, and foodwraps. Also called LLDPE, LLDPE resin.

linear polyethylenes: Linear polyethylenes arepolyolefins with linear carbon chains. They are pre-pared by copolymerization of ethylene with smallamounts of higher alfa-olefins such as 1-butene.Linear polyethylenes are stiff, tough, and have goodresistance to environmental cracking and low tem-peratures. Processed by extrusion and molding. Usedto manufacture films, bags, containers, liners, pro-files, and pipes.

liquid crystal polymers: Thermoplastic aromaticcopolyesters with highly ordered structure. Havegood tensile and flexural properties at high temper-atures, chemical, radiation and fire resistance, andweatherability. Processed by sintering and injectionmolding. Used to substitute ceramics and metals inelectrical components, electronics, chemical appa-ratus, and aerospace and auto parts. Also calledLCP.

lithopone red: A weather-resistant inorganic redpigment containing cadmium sulfoselenide, zincsulfide, barium sulfate, and zinc oxide. Used inplastics.

lithopone yellow: A weather-resistant inorganicyellow pigment (Color Index Number 77199:1) con-taining cadmium sulfide, zinc sulfide, barium sulfate,and zinc oxide. Used in plastics. Also called C.I.Pigment Yellow 37:1.

LLDPE: See linear low density polyethylene.

424 The Effects of UV Light and Weather on Plastics and Elastomers

LLDPE resin: See linear low density polyethylene.

low density polyethylene: A branched-chainthermoplastic with density 0.91–0.94 g/cm3. Hasgood impact strength, flexibility, transparency,chemical resistance, dielectric properties, and lowwater permeability and brittleness temperature,but poor heat, stress cracking and fire resistanceand weatherability. Processed by extrusion coating,injection and blow molding, and film extrusion. Canbe cross-linked. Used in packaging and shrink films,toys, bottle caps, cable insulation, and coatings.Alsocalled LDPE.

luminous transmittance: See transmittance.

M

macroscopic properties: See thermodynamicproperties.

magnesia: See magnesium oxide.

magnesium oxide: A while powder, MgO, pro-duced by calcining magnesium carbonate or hydrox-ide in several grades (technical, fused, rubber, etc.).Used as filler, thickening agent in polyesters, andinorganic rubber accelerator. Also called magnesia.

masking filler: A filler or pigment with low hidingpower added in small amounts to clear plastics tomask their natural tint (e.g., blue pigments are addedto mask the yellow tine). Also called color maskingagent.

masstone green vulcanizates: Vulcanized rubbercontaining no other pigments but a green one.

matte surface: A dull or low-gloss surface that ismore prone to light scattering than reflection.

MBT: See 2-mercaptobenzothiazole.

mechanical properties: Properties describing thereaction of physical systems to stress and strain.

melamine resins: Thermosetting resins prepared bythe condensation of formaldehyde with melamine.

Have good hardness, scratch and fire resistance, clar-ity, colorability, rigidity, dielectric properties, andtensile strength, but poor impact strength. Moldinggrades are filled. Processed by compression, transfer,and injection molding, impregnation, and coating.Used in cosmetic containers, appliances, tableware,electrical insulators, furniture laminates, adhesives,and coatings.

mercaptobenzothiazole(2-): A nitrogen- andsulfur-containing polyheterocyclic organic thiolused as vulcanization accelerator for rubber.Requires zinc oxide as an activator. Its vulcanizateshave a good aging resistance. A yellowish pow-der with distinctive odor. Combustible. Also calledMBT.

mercury cadmium red: An inorganic red pigmentcontaining mercury and cadmium sulfides; usedmainly in rubber; has good light and heat resistance.

methylfluorosilicones: Silicone rubbers containingpendant fluorine and methyl groups. Have goodchemical and heat resistance. Used in gasoline lines,gaskets, and seals. Also called FMQ.

methylphenylsilicones: Silicone rubbers contain-ing pendant phenyl and methyl groups. Have goodresistance to heat, oxidation, and radiation, andcompatibility with plastics.

methylsilicone: Silicone rubbers containing pen-dant methyl groups. Have good heat and oxida-tion resistance. Used in electrical insulations andcoatings. Also called MQ.

methylvinylfluorosilicone: Silicone rubbers con-taining pendant vinyl, methyl, and fluorine groups.Can be additionally cross-linked via vinyl groups.Have good resistance to petroleum products atelevated temperatures.

methylvinylsilicone: Silicone rubbers containingpendant methyl and vinyl groups. Can be addition-ally cross-linked via vinyl groups.Vulcanized to highdegrees of cross-linking. Used in sealants, adhesives,coatings, cables, gaskets, tubing, and electrical tape.

microbiological attack: See biodegradation.

Glossary of Terms 425

micrometer: A unit of length equal to 1 × 10−6

meter. Its symbol is the Greek small letter µ or µm.

microtensile specimen: Asmall specimen as speci-fied in ASTM D1708 for determining tensile proper-ties of plastics. It has a maximum thickness 3.2 mmand a minimum of length 38.1 mm. Tensile prop-erties determined with this specimen include yieldstrength, tensile strength, tensile strength at break,and elongation at break.

migration: A moss-transfer process in which thematter moves from one place to another usually in aslow and spontaneous fashion. In plastics and coat-ings, migration of pigments, fillers, plasticizers, andother ingredients via diffusion or floating to the sur-face or through interface to other materials results invarious defects called blooming, chalking, bronzing,flooding, bleeding, etc.

mildew resistance: The ability of a material suchas plastics or nonmetallic coatings to resist fungusgrowth and deterioration caused by fungi such ascommon mold, including polymer degradation anddiscoloration. Also called fungus resistance.

mineral salt medium: A corrosive medium such asan aqueous solution, containing mineral or inorganicsalts such as sodium chloride (NaCl). Used in mate-rial testing, especially of anticorrosive properties.

modified polyphenylene ether: Thermoplasticpolyphenylene ether alloys with impact polystyrene.Have good impact strength and resistance to heatand fire, but poor resistance to solvents. Processed byinjection and structural foam molding and extrusion.Used in auto parts, appliances, and telecommuni-cation devices. Also called MPE, MPO, modifiedpolyphenylene oxide.

modified polyphenylene oxide: See modifiedpolyphenylene ether.

modulus of rupture: See flexural strength.

modulus of rupture in bending: See flexuralstrength.

molding defects: Structural and other defects inmaterial caused inadvertently during molding by

using wrong tooling, process parameters, ingredi-ents, etc. Also called molding flaw. See also design,etc. Usually preventable.

molding flaw: See molding defects.

molecular weight: The sum of the atomic weightsof all atoms in a molecule. Also called MW.

molecular weight distribution: The relativeamounts of polymeric molecules of different weightsin a specimen. Note: The molecular weight distribu-tion can be expressed in terms of the ratio betweenweight- and number-average molecular weights.Also called polydispersity, MWD, molecular weightratio.

molecular weight ratio: See molecular weight dis-tribution.

Monastral Blue: A blue copper phthalocyaninepigment with excellent light stability and high stabil-ity to vulcanization and aging; non-bleeding. Usedin paints, rubbers, plastics such as PVC, and textilessuch as rayon. Since it has a low hiding power smallamounts of it (2–10 ppm) are added to clear plasticsto neutralize slightly yellow tint.

MPE: See modified polyphenylene ether.

MPO: See modified polyphenylene ether.

MQ: See methylsilicone.

mulch film: A film, usually dark-colored PVC film,used instead of mulch in agriculture (e.g., to pre-vent fruit rotting and runners and weed growth incultivation of strawberries).

MW: See molecular weight.

MWD: See molecular weight distribution.

N

nanometer: Aunit of length equal to 1×10−9 meter.Often used to denote the wavelength of radiation,especially in the UV and visible spectral region.Alsocalled nm.

426 The Effects of UV Light and Weather on Plastics and Elastomers

neoprene rubber: Polychloroprene rubbers withgood resistance to petroleum products, heat andozone, weatherability, and toughness.

nickel complex light stabilizer: Light stabilizersfor plastics comprising nickel complexes such asnickel acetylacetonate, dithiolate, or pyridylbenzim-idazole complexes. Their stabilization mechanismdiffers but most act as UV absorbers.

nitrile rubber: Rubbers prepared by free-radicalpolymerization of acrylonitrile with butadiene. Havegood resistance to petroleum products, heat, andabrasion. Used in fuel hoses, shoe soles, gaskets, oilseals, and adhesives.

nitroarylamine: A class of aromatic amines con-taining benzene ring(s) with nitro (NO2 group sub-stituent(s), such as nitroaniline (O2NC6H4NH2).Used as organic intermediates (e.g., in dye synthesis)and antioxidants in propellants and plastics.

nm: See nanometer.

nonelastomeric thermoplastic polyurethanes:See rigid thermoplastic polyurethanes.

nonelastomeric thermosetting polyurethane:Curable mixtures of isocyanate prepolymers ormonomers. Have good abrasion resistance and low-temperature stability, but poor heat, fire, and solventresistance and weatherability. Processed by reac-tion injection and structural foam molding, casting,potting, encapsulation, and coating. Used in heatinsulation, auto panels and trim, and housings forelectronic devices.

notch effect: The effect of the presence of a speci-men notch or its geometry on the outcome of a testsuch as an impact strength test of plastics. Notch-ing results in local stresses and accelerates failure inboth static and cycling testing (mechanical, ozonecracking, etc.).

notched Izod: See notched Izod impact energy.

notched Izod impact: See notched Izod impactenergy.

notched Izod impact energy: The energy requiredto break a notched specimen, equal to the difference

between the energy in the striking member of theIzod-type impact apparatus at the instant of impactand the energy remaining after complete fracture ofthe specimen. Note: Energy depends on geometry(e.g., width, depth, shape) of the notch, on the cross-sectional area of the specimen, and on the place ofimpact (on the side of the notch or on the oppositeside). In some tests a notch is made on both sidesof the specimen. Also called notched Izod impactstrength, notched Izod impact, notched Izod.

notched Izod impact strength: See notched Izodimpact energy.

nylon: Thermoplastic polyamides often preparedby ring-opening polymerization of lactam. Havegood resistance to most chemicals, abrasion, andcreep, good impact and tensile strengths, barrierproperties, and low friction, but poor resistance tomoisture and light. Have high mold shrinkage. Pro-cessed by injection, blow, and rotational molding,extrusion, and powder coating. Used in fibers, autoparts, electrical devices, gears, pumps, appliancehousings, cable jacketing, pipes, and films.

nylon 6: Thermoplastic polymer of caprolactam.Has good weldability and mechanical properties butrapidly picks up moisture which results in strengthlosses. Processed by injection, blow, and rotationalmolding and extrusion. Used in fibers, tire cord, andmachine parts.

nylon 11: Thermoplastic polymer of 11-amino-undecanoic acid. Has good impact strength,hardness, abrasion resistance, processability, anddimensional stability. Processed by powder coating,rotational molding, extrusion, and injection molding.Used in electric insulation, tubing, profiles, bearings,and coatings.

nylon 12: Thermoplastic polymer of lauric lac-tam. Has good impact strength, hardness, abrasionresistance, and dimensional stability. Processed bypowder coating, rotational molding, extrusion, andinjection molding. Used in sporting goods and autoparts.

nylon 46: Thermoplastic copolymer of2-pyrrolidone and caprolactam.

Glossary of Terms 427

nylon 66: Thermoplastic polymer of adipic acid andhexamethylenediamine. Has good tensile strength,elasticity, toughness, heat resistance, abrasionresistance, and solvent resistance, but low weather-ability and color resistance. Processed by injectionmolding and extrusion. Used in fibers, bearings,gears, rollers, and wire jackets.

nylon 610: Thermoplastic polymer of hexa-methylenediamine and sebacic acid. Has decreasedmelting point and water absorption and good reten-tion of mechanical properties. Processed by injectionmolding and extrusion. Used in fibers and machineparts.

nylon 612: Thermoplastic polymer of 1,12-dodecanedioic acid and hexamethylenediamine. Hasgood dimensional stability, low moisture absorption,and good retention of mechanical properties. Pro-cessed by injection molding and extrusion. Used inwire jackets, cable sheath, packaging film, fibers,bushings, and housings.

nylon 666: Thermoplastic polymer of adipic acid,caprolactam, and hexamethylenediamine. Has goodstrength, toughness, abrasion and fatigue resistance,and low friction, but high moisture absorption andlow dimensional stability. Processed by injectionmolding and extrusion. Used in electrical devicesand auto and mechanical parts.

nylon MXD6: Thermoplastic polymer of m-xylyleneadipamide. Has good flexural strength andchemical resistance, but decreased tensile strength.

O

olefin resins: See polyolefins.

olefinic resins: See polyolefins.

olefinic thermoplastic elastomers: Blends ofEPDM or EP rubbers with polypropylene orpolyethylene, optionally cross-linked. Have lowdensity, good dielectric and mechanical proper-ties, and processibility, but low oil resistance andhigh flammability. Processed by extrusion, injectionand blow molding, thermoforming, and calendering.Used in auto parts, construction, wire jackets, andsporting goods. Also called TPO.

opacity: See hiding power.

optical characteristics: See optical properties.

optical properties: The effects of a material ormedium on light or other electromagnetic radiationpassing through it, such as absorption, reflection, etc.Also called optical characteristics.

optical transmittance: See transmittance.

organic compounds: Chemical compounds basedon carbon chains and rings and also containinghydrogen that can be entirely or partially substi-tuted with oxygen, nitrogen and other elements,Alsocalled organic substances.

organic compounds: See halogen compounds.

organic substances: See organic compounds.

outgassing rate: See degassing rate.

oxazolines: Heterocyclic compounds containingfive-membered rings in which one carbon is replacedwith an oxygen atom and another with a nitrogenatom. Oxazolines are colorless liquids soluble inorganic solvents and water. Used as intermediatesin the synthesis of surfactants.

ozone: An allotropic form of oxygen, O3. Unstablegas formed naturally in air by lightning or in thestratosphere by the UV portion of solar radiation,or formed as a result of combustion of fossil fuels(i.e., in exhaust gases from automobiles). O3 is anactive oxidizing agent that accelerates deteriorationof rubber.

P

PA: See polyamides.

PABM: See polyaminobismaleimide resins.

paraffinic plasticizer: Plasticizers for plastics com-prising liquid or solid long-chain alkanes or paraffins(saturated linear or branched hydrocarbons).

parts per hundred: A relative unit of concentra-tion, parts of one substance per 100 parts of another.Parts can be measured by weight, volume, count,or any other suitable unit of measure. Used often to

428 The Effects of UV Light and Weather on Plastics and Elastomers

denote the composition of a blend or mixture, such asplastics, in terms of the parts of a minor ingredient,such as plasticizer, per 100 parts of a major, such asresin. Also called phr.

parts per hundred million: A relative unit of con-centration, parts of one substance per 100 millionparts of another. Parts can be measured by weight,volume, count, or any other suitable unit of mea-sure. Used often to denote a very small concentrationof a substance, such as an impurity or a toxin, in amedium, such as air. Also called pphm.

PBI: See polybenzimidazoles.

PBT: See polybutylene terephthalate.

PC: See polycarbonates.

PCT: See polycyclohexylenedimethylene tereph-thalate.

PCTG: See glycol-modified polycyclohexylene-dimethylene terephthalate.

PE copolymer: See polyethylene copolymer.

PEEK: See polyetheretherketone.

PEI: See polyetherimides.

PEK: See polyetherketone.

pendant aromatic rings: Aromatic (conjugatedunsaturated rings such as those of benzene, C6H6)rings attached to the main chain of a polymermolecule.

Penicillium funiculosum: A species of commonmold belonging to the genus Penicillium. Used aloneor in artificial mixtures with other fungi to pre-pare cultures for the testing of mildew resistance ofmaterials such as plastics, or fungicidal activity ofantimildew agents or fungicides.

pentaerythritol: A polyol, C(CH2OH)4, preparedby the reaction of acetaldehyde with excessformaldehyde in an alkaline medium. Used as aplasticizer and as a monomer in alkyd resins.

percentage light transmittance: See transmit-tance.

perfluoroalkoxy resins: Thermoplastic polymersof perfluoroalkoxyethylenes. Has good creep, heat,and chemical resistance and processibility, but lowcompressive and tensile strengths. Processed bymolding, extrusion, rotational molding, and powdercoating. Used in films, coatings, pipes, containers,and chemical apparatus linings. Also called PFA.

PES: See polyethersulfone.

PET: See polyethylene terephthalate.

PETG: See polycyclohexylenedimethylene ethy-lene terephthalate.

PFA: See perfluoroalkoxy resins.

phase transition: See phase transition properties.

phase transition point: The temperature at whicha phase transition occurs in a physical system suchas a material. Note: An example of phase transi-tion is glass transition. Also called phase transitiontemperature, transition point, transition temperature.

phase transition properties: Properties of physicalsystems such as materials associated with their tran-sition from one phase to another (e.g., from liquid tosolid phase). Also called phase transition.

phase transition temperature: See phase transi-tion point.

phenolic resins: Thermoset polymers of phenolswith excess or deficiency of aldehydes, mainlyformaldehyde, to give resole or novolak resins,respectively. Heat-cured resins have good dielec-tric properties, hardness, thermal stability, rigidity,and compressive strength but poor chemical resis-tance and dark color. Processed by coating, pot-ting, compression, transfer, or injection moldingand extrusion. Used in coatings, adhesives, pottingcompounds, handles, electrical devices, and autoparts.

photo bleaching: See photochemical bleaching.

Glossary of Terms 429

photo-Fries rearrangement: See photochemicalFries rearrangement.

photochemical bleaching: Complete loss of colorof the material as a result of photodegradation ofcolored substances present in its surface layer. Alsocalled photobleaching.

photochemical degradation: Degradation as aresult of light-induced reactions such as photolysis.Also called photodegradation.

photochemical Fries rearrangement: Rearrange-ment of phenolic esters to o- and/or p-phenolicketones induced by light. Also called photo-Friesrearrangement.

photodegradation: See photochemical degra-dation.

photo-oxidation: Oxidation of a substance such aspolymer, initiated by light, especially the UV portionof it.An important part of polymer photodegradation.Usually proceeds via formation of peroxides, whichreadily decompose to highly reactive free radicals.Inhibited or retarded in polymers by antioxidants andlight stabilizers.

phr: See parts per hundred.

phthalocyanine: Anitrogen-containing heterocyclicorganic compound, (C6H4C2N)2(C6H4C2NH)2N4,belonging to the group of benzoporphyrins andcomprising four isoindole groups jointed by fournitrogen atoms. Readily forms salt complexes withcopper, chromium, iron, etc., that are important greenand blue dyes and pigments. These pigments havehigh light and chemical stability. Used in coatings,plastics, and textiles.

PI: See polyimides.

plasticizer: A substance incorporated into a mate-rial such as a plastic or rubber to increase its softness,processability, and flexibility via solvent or lubri-cating action or by lowering its molecular weight.Plasticizers can lower melt viscosity, improve flow,and increase low-temperature resilience of the mate-rial. Most plasticizers are nonvolatile organic liquids

or low-melting point solids such as dioctyl phtha-late or stearic acid. They have to be nonbleeding,nontoxic, and compatible with the material. Some-times plasticizers play a dual role as stabilizers orcross-linkers.

plastics: See polymers.

PMMA: See polymethyl methacrylate.

PMP: See polymethylpentene.

polyacrylates: See acrylic resins.

polyallomer: Crystalline thermoplastic blockcopolymers of ethylene, propylene, and other olefins.Have good impact strength and flex life and lowdensity.

polyamide thermoplastic elastomers: Copoly-mers containing soft polyether and hard polyamideblocks having good chemical, abrasion, and heatresistance, impact strength, and tensile properties.Processed by extrusion and injection and blow mold-ing. Used in sporting goods, auto parts, and electricaldevices. Also called polyamide TPE.

polyamide TPE: See polyamide thermoplasticelastomers.

polyamides: Thermoplastic aromatic or aliphaticpolymers of dicarboxylic acids and diamines, ofamino acids, or of lactams. Have good mechani-cal properties, chemical resistance, and antifrictionproperties. Processed by extrusion and molding.Used in fibers and molded parts. Also called PA.

polyaminobismaleimide resins: Thermoset poly-mers of aromatic diamines and bismaleimides havinggood flow and thermochemical properties and flameand radiation resistance. Processed by casting andcompression molding. Used in aircraft parts andelectrical devices. Also called PABM.

polyarylamides: Thermoplastic crystalline poly-mers of aromatic diamines and aromatic dicarboxylicanhydrides. Have good heat, fire, and chemicalresistance, property retention at high temperatures,dielectric and mechanical properties, and stiffness,

430 The Effects of UV Light and Weather on Plastics and Elastomers

but poor light resistance and processibility. Pro-cessed by solution casting, molding, and extrusion.Used in films, fibers, and molded parts.

polyarylsulfone:Thermoplastic aromatic polyether-polysulfone having good heat, fire, and chemicalresistance, impact strength, resistance to environ-mental stress cracking, dielectric properties, andrigidity. Processed by injection and compressionmolding and extrusion. Used in circuit boards, lamphousings, piping, and auto parts.

polybenzimidazoles: Mainly polymers of 3,3′,4′-tetraminonbiphenyl(diaminobenzidine) and diphenylisophthalate. Have good heat, fire, and chemicalresistance. Used as coatings and fibers in aerospaceand other high-temperature applications. Also calledFBI.

polybutylene terephthalate: Thermoplastic poly-mer of dimethyl terephthalate and butanediol. Hasgood tensile strength, dielectric properties, andchemical and water resistance, but poor impactstrength and heat resistance. Processed by injec-tion and blow molding, extrusion, and thermoform-ing. Used in auto body parts, electrical devices,appliances, and housings. Also called PBT.

polycarbodiimide: Polymers containing –N=C=N– linkages in the main chain, typically formedby catalyzed polycondensation of polyisocyanates.They are used to prepare open-celled foams withsuperior thermal stability. Sterically hindered poly-carbodiimides are used as hydrolytic stabilizers forpolyester-based urethane elastomers.

polycarbonate: See polycarbonates.

polycarbonate-polyesteralloys: High-performancethermoplastics processed by injection and blowmolding. Used in auto parts.

polycarbonate resins: See polycarbonates.

polycarbonates: Polycarbonates are thermoplas-tics prepared by either phosgenation of dihydricaromatic alcohols such as bisphenol A or by trans-esterification of these alcohols with carbonates(e.g., diphenyl carbonate). Polycarbonates consistof chains with repeating carbonyldioxy groups and

can be aliphatic or aromatic. They have very goodmechanical properties, especially impact strength,low moisture absorption, and good thermal andoxidative stability. They are self-extinguishing andsome grades are transparent. Polycarbonates haverelatively low chemical resistance and resistance tostress cracking. Processed by injection and blowmolding, extrusion, thermoforming at relatively highprocessing temperatures. Used in telephone parts,dentures, business machine housings, safety equip-ment, nonstaining dinnerware, food packaging, etc.Also called polycarbonate, PC, polycarbonate resins.

polychlorotrifluoroethylene: Thermoplastic poly-mer of chlorotrifluoroethylene. Has good trans-parency, barrier properties, tensile strength, andcreep resistance, modest dielectric properties andsolvent resistance, and poor processibility. Processedby extrusion, injection and compression molding,and coating. Used in chemical apparatus, low-temperature seals, films, and internal lubricants.Alsocalled CTFE.

polycyclohexylenedimethylene ethylene tereph-thalate: Thermoplastic polymer of cyclohexylene-dimethylenediol, ethylene glycol, and terephthalicacid. Has good clarity, stiffness, hardness, and low-temperature toughness. Processed by injection andblow molding and extrusion. Used in containersfor cosmetics and foods, packaging film, medi-cal devices, machine guards, and toys. Also calledPETG.

polycyclohexylenedimethylene terephthalate:Thermoplastic polymer of cyclohexylenedi-methylenediol and terephthalic acid. Has good heatresistance. Processed by molding and extrusion.Alsocalled PCT.

polydispersity: See molecular weight distribution.

polyester resins: See polyesters.

polyester thermoplastic elastomers: Copolymerscontaining soft polyether and hard polyester blockshaving good dielectric strength, chemical and creepresistance, dynamic performance, appearance, andretention of properties in a wide temperature range,but poor light resistance. Processed by injection,blow, and rotational molding, extrusion casting, and

Glossary of Terms 431

film blowing. Used in electrical insulation, medicalproducts, auto parts, and business equipment. Alsocalled polyester TPE.

polyester TPE: See polyester thermoplasticelastomers.

polyesters: Abroad class of polymers usually madeby the condensation of a diol with dicarboxylicacid or anhydride. Polyesters consist of chains withrepeating carbonyloxy group and can be aliphaticor aromatic. There are thermosetting polyesterssuch us alkyd resins and unsaturated polyesters andthermoplastic polyesters such as PET. The prop-erties, processing methods, and applications ofpolyesters vary widely. Also called polyester resins.

polyetheretherketone: Semi-crystalline thermo-plastic aromatic polymer. Has good chemical, heat,fire, and radiation resistance, toughness, rigidity,bearing strength, and processibility. Processed byinjection molding, spinning, cold forming, and extru-sion. Used in fibers, films, auto engine parts, aero-space composites, and electrical insulation. Alsocalled PEEK.

polyetherimides: Thermoplastic cyclized poly-mers of aromatic diether dianhydrides and aromaticdiamines. Have good chemical, creep, and heatresistance and dielectric properties. Processed byextrusion, thermoforming, and compression, injec-tion, and blow molding. Used in auto parts, jetengines, surgical instruments, industrial apparatus,food packaging, cookware, and computer disks.Alsocalled PEI.

polyetherketone: Thermoplastic having good heatand chemical resistance and thermal stability. Usedin advanced composites, wire coating, filters, inte-grated circuit boards, and bearings.Also called PEK.

polyethersulfone: Thermoplastic aromatic poly-mers having good heat and fire resistance, trans-parency, dielectric properties, dimensional stability,rigidity, and toughness, but poor solvent and stresscracking resistance, processibility, and weatherabil-ity. Processed by injection, blow, and compressionmolding and extrusion. Used in high-temperatureapplications, electrical devices, medical devices,

housings, and aircraft and auto parts. Also calledPES.

polyethylene copolymer: Thermoplastic polymersof ethylene with other olefins such as propylene. Pro-cessed by molding and extrusion. Also called PEcopolymer.

polyethylene terephthalate: Thermoplastic poly-mer of ethylene glycol with terephthalic acid. Hasgood hardness, wear and chemical resistance, dimen-sional stability, and dielectric properties. High-crystallinity grades have good tensile strength andheat resistance. Processed by extrusion and injectionand blow molding. Used in fibers, food packag-ing (films, bottles, trays), magnetic tapes, and photofilms. Also called PET.

polyimides: Thermoplastic aromatic cyclized poly-mers of trimellitic anhydride and aromatic diamine.Have good tensile strength, dimensional stability,dielectric and barrier properties, and creep, impact,heat, and fire resistance, but poor processibility.Processed by compression and injection molding,powder sintering, film casting, and solution coat-ing. Thermoset uncyclized polymers are heat curableand have good processability. Processed by transferand injection molding, lamination, and coating. Usedin jet engines, compressors, sealing coatings, autoparts, and business machines. Also called PI.

polymer chain unsaturation: See chemicalunsaturation.

polymers: Polymers are high-molecular weightorganic or inorganic compounds the molecules ofwhich comprise linear, branched, cross-linked, orotherwise shaped chains of repeating moleculargroups. Synthetic polymers are prepared by polymer-ization of one or more monomers. The monomersare low-molecular weight substances with one ormore reactive bonds or functional groups.Also calledresins, plastics.

polymethyl methacrylate: Thermoplastic polymerof methyl methacrylate having good transparency,weatherability, impact strength, and dielectric prop-erties. Processed by compression and injection mold-ing, casting, and extrusion. Used in lenses, sheets,

432 The Effects of UV Light and Weather on Plastics and Elastomers

airplane canopies, signs, and lighting fixtures. Alsocalled PMMA.

polymethylpentene: Thermoplastic polymer of4-methyl-1-pentene having low density, good trans-parency, rigidity, dielectric and tensile properties,and heat and chemical resistance. Processed byinjection and blow molding and extrusion. Used inlaboratory ware, coated paper, light fixtures, autoparts, and electrical insulation. Also called PMP.

polyolefin resins: See polyolefins.

polyolefins: Polyolefins are a broad class ofhydrocarbon-chain elastomers or thermoplasticsusually prepared by the addition (co)polymerizationof alkenes such as ethylene. There are branchedand linear polyolefins and some are chemically orphysically modified. Unmodified polyolefins haverelatively low thermal stability and a nonporous,nonpolar surface with poor adhesive properties. Pro-cessed by extrusion and injection, blow, and rota-tional molding. Polyolefins are used more and havemore applications than any other polymers. Alsocalled olefinic resins, olefin resins, polyolefin resins.

polyphenylene ether nylon alloys: Thermoplas-tics having improved heat and chemical resistanceand toughness. Processed by molding and extrusion.Used in auto body parts.

polyphenylene sulfide: High-performance engi-neering thermoplastic having good chemical, water,fire, and radiation resistance, dimensional stabil-ity, and dielectric properties, but decreased impactstrength and poor processibility. Processed byinjection, compression, and transfer molding andextrusion. Used in hydraulic components, bearings,electronic parts, appliances, and auto parts. Alsocalled PPS.

polyphenylene sulfide sulfone: Thermoplastic hav-ing good heal, fire, creep, and chemical resistanceand dielectric properties. Processed by injectionmolding. Used in electrical devices. Also calledPPSS.

polyphthalamide: Thermoplastic polymer of aro-matic diamine and phthalic anhydride. Has goodheat, chemical, and fire resistance, impact strength,

retention of properties at high temperatures, dielec-tric properties, and stiffness, but decreased lightresistance and poor processibility. Processed bysolution casting, molding, and extrusion. Used infilms, fibers, and molded parts. Also called PPA.

polypropylene: Thermoplastic polymer of propy-lene having low density and good flexibility andresistance to chemicals, abrasion, moisture, andstress cracking, but decreased dimensional stability,mechanical strength, and light, fire, and heat resis-tance. Processed by injection molding, spinning, andextrusion. Used in fibers and films for adhesive tapesand packaging. Also called PP.

polystyrene: Polystyrenes are thermoplastics pro-duced by polymerization of styrene with or withoutmodification (e.g., by copolymerization or blend-ing) to make impact resistant or expandable grades.They have good rigidity, high dimensional stabil-ity, low moisture absorption, optical clarity, highgloss, and good dielectric properties. Unmodifiedpolystyrenes have poor impact strength and resis-tance to solvents, heat, and UV radiation. Processedby injection molding, extrusion, compression mold-ing, and foam molding. Used widely in medicaldevices, house wares, food packaging, electronics,and foam insulation. Also called polystyrenes, PS,polystyrol.

polystyrenes: See polystyrene.

polystyrol: See polystyrene.

polysulfones: Thermoplastics, often aromatic andwith ether linkages, having good heat, fire, and creepresistance, dielectric properties, transparency, butpoor weatherability, processibility, and stress crack-ing resistance. Processed by injection, compression,and blow molding and extrusion. Used in appliances,electronic devices, auto parts, and electric insulators.Also called PSO.

polytetrafluoroethylene: Thermoplastic polymerof tetrafluoroethylene having good dielectric prop-erties, chemical, heat, abrasion, and fire resis-tance, antiadhesive properties, impact strength,and weatherability, but decreased strength, pro-cessibility, barrier properties, and creep resistance.Processed by sinter molding and powder codling.

Glossary of Terms 433

Used in nonstick coatings, chemical apparatus, elec-trical devices, bearings, and containers. Also calledPTFE.

polyurethane resins: See polyurethanes.

polyurethanes: Polyurethanes (Pus) are a broadclass of polymers consisting of chains with a repeat-ing urethane group, prepared by the condensationof polyisocyanates with polyols (e.g., polyesteror polyether diols). PUs may be thermoplastic orthermosetting, elastomeric or rigid, cellular or solid,and offer a wide range of properties depending ontheir composition and molecular structure. ManyPUs have high abrasion resistance, good retention ofproperties at low temperatures, and good foamabil-ity. Some have poor heat resistance, weatherability,and resistance to solvents. PUs are flammable andcan release toxic substances. Thermoplastic PUsare not cross-linked and are processed by injec-tion molding and extrusion. Thermosetting PUs canbe cured at relatively low temperatures and givefoams with good heat insulating properties. Theyare processed by reaction injection molding, rigidand flexible foam methods, casting, and coating. PUsare used in load bearing rollers and wheels, acous-tic clamping materials, sporting goods, seals andgaskets, heat insulation, potting, and encapsulation.Also called PUR, PU, urethane polymers, urethaneresins, urethanes, polyurethane resins.

polyvinyl chloride: Thermoplastic polymer ofvinyl chloride, available in rigid and flexible forms.Has good dimensional stability, fire resistance, andweatherability, but decreased heat and solvent resis-tance and high density. Processed by injection andblow molding, calendering, extrusion, and pow-der coating. Used in films, fabric coatings, wireinsulation, toys, bottles, and pipes. Also called PVC.

polyvinyl fluoride: Crystalline thermoplastic poly-mer of vinyl fluoride having good toughness, flex-ibility, weatherability, and low temperature andabrasion resistance. Processed by film techniques.Used in packaging, glazing, and electrical devices.Also called PVF.

polyvinylidene chloride: Stereoregular thermo-plastic polymer of vinylidene chloride having good

abrasion and chemical resistance and barrier prop-erties. Processed by molding and extrusion. Used infood packaging films, bag liners, pipes, upholstery,fibers, and coatings. Also called PVDC.

polyvinylidene fluoride: Thermoplastic polymerof vinylidene fluoride having good strength, proces-sibility, wear, fire, solvent, and creep resistance, andweatherability, but decreased dielectric propertiesand heat resistance. Processed by extrusion, injec-tion, and transfer molding and powder coating. Usedin electrical insulation, pipes, chemical apparatus,coatings, films, containers, and fibers. Also calledPVDF.

PP: See polypropylene.

PPA: See polyphthalamide.

pphm: See parts per hundred million.

ppm: A unit for measuring small concentrations ofa material or substance as the number of its parts(arbitrary quantity) per million parts of mediumconsisting of another material or substance.

PPS: See polyphenylene sulfide.

PPSS: See polyphenylene sulfide sulfone.

prevulcanization: See scorching.

process characteristics: See processing para-meters.

process conditions: See processing parameters.

process media: See processing agents.

process parameters: See processing parameters.

process pressure: See processing pressure.

process rate: See processing rate.

process speed: See processing rate.

process time: See processing time.

process velocity: See processing rate.

processing additives: See processing agents.

434 The Effects of UV Light and Weather on Plastics and Elastomers

processing agents: Agents or media used in themanufacture, preparation, and treatment of a mate-rial or article to improve its processing or properties.The agents often become a part of the material. Alsocalled process media, processing aids, processingadditives.

processing aids: See processing agents.

processing defects: Structural and other defectsin a material or article caused inadvertently dur-ing manufacturing, preparation, and treatment pro-cesses by using wrong tooling, process parameters,ingredients, part design, etc. Usually preventable.Also called processing flaw, defects, flaw. See alsocracking.

processing flaw: See, processing defects.

processing methods: Method names and designa-tions for material article manufacturing, preparation,and treatment processes. Note: Both common andstandardized names are used. Also called processingprocedures.

processing parameters: Measurable parameterssuch as temperature prescribed or maintained dur-ing material or article manufacture, preparation, andtreatment processes. Also called process character-istics, process conditions, process parameters.

processing pressure: Pressure maintained in anapparatus during material or article manufacture,preparation, and treatment processes. Also calledprocess pressure. See also pressure.

processing procedures: See processing methods.

processing rate: Speed of the process in manu-facture, preparation, and treatment of a material orarticle. It usually denotes the change in a processparameter per unit of time or the throughput speedof material in a unit of weight, volume, etc., per unitof time. Also called process speed, process velocity,process rate.

processing time: Time required for the completionof a process in the manufacture, preparation, andtreatment of a material or article. Also called processtime, cycle time.

promoter: Sec accelerator.

PS: See polystyrene.

PSO: See polysulfones.

PTFE: See polytetrafluoroethylene.

PU: See polyurethanes.

PUR: See polyurethanes.

PVC: See polyvinyl chloride.

PVDC: See polyvinylidene chloride.

PVDF: See polyvinylidene fluoride.

PVF: See polyvinyl fluoride.

Q

QUV accelerated weathering tester: See fluores-cent UV lamp-condensation apparatus.

QFS-40 lamp: A fluorescent UV-B lamp with peakemission at 313 nm that provides high UV radia-tion output for accelerated indoor lightfastness andweatherability testing of materials such as plastics,nonmetallic coatings, and textiles. The lamp doesnot match closely the sunlight spectrum in the shortwavelength region.Also called FS-40 (UV-B) lamps,FS-40, F40 UVB, F40-UVB, FS-401 lamp.

quartz innerfilter: An inner filter made from quartzglass in a xenon-arc lamp that in combination with asoda-lime or borosilicate glass outer filter selectivelyscreens radiation output, especially in the short UVwavelength region, to simulate window glass-filtereddaylight or sunlight, respectively, in an acceleratedlight exposure testing apparatus.

quinacridone red: Alight-fast, chemically resistantorganic red pigment used in paints, inks, and plastics.Properties of quinacridone pigments are similar tothose of phthalocyanine pigments.

QUV: See fluorescent UV lamp-condensationapparatus.

Glossary of Terms 435

R

Ra: See roughness average.

radiant flux density: See irradience.

reaction injection molding system: Liquidcompositions, mostly polyurethane-based, of ther-mosetting resins, prepolymers, monomers, or theirmixtures. Have good processibility, dimensional sta-bility, and flexibility. Processed by foam moldingwith in-mold curing at high temperatures. Used inauto parts and office furniture, Also called RIM.

relative humidity: The ratio of the actual vaporpressure of the air to the saturation vapor pressure.Also called RH.

relative viscosity: The ratio of solution viscosity tothe viscosity of the solvent.

resins: See polymers.

resorcinol-modified phenolic resins: Thermoset-ting polymers of phenol, formaldehyde, and resor-cinol having good heat and creep resistance anddimensional stability.

RH: See relative humidity.

rigid thermoplastic polyurethanes: Right ther-moplastic polyurethanes are not chemically cross-linked. They have high abrasion resistance, goodretention of properties at low temperatures, butpoor heat resistance, weatherability, and resistanceto solvents. Rigid thermoplastic polyurethanes areflammable and can release toxic substances. Pro-cessed by injection molding and extrusion. Alsocalled rigid thermoplastic urethanes, nonelastomericthermoplastic polyurethanes.

rigid thermoplastic urethanes: See rigid thermo-plastic polyurethanes.

Rim: See reaction injection molding system.

roughness average: A height parameter of surfaceroughness equal to the average absolute deviation ofsurface profile from the mean line, calculated as theintegrated area of peaks and valleys above and below

the mean line, respectively, divided by the length ofthis line. And called Ra.

rutile TiO2: See rutile titanium oxide.

rutile titanium oxide: One of the naturally occur-ring crystal forms of titanium dioxide. Used as awhite or opacifying pigment in a wide range of mate-rials including coatings and plastics. Rutile titaniumdioxide has a higher refractive index and opacitythan anatase titanium dioxide, another crystal form ofthis oxide. The pigment is nonmigrating, heat resis-tant, chemically inert, and lightfast.Also called rutileTiO2.

S

SAE J576: A Society of Automotive Engineersrecommended practice for evaluating the suitabil-ity of plastics intended for molded optical partssuch as lenses and reflectors of motor vehicle light-ing devices. The suitability is determined by theextent of change of optical properties after out-door conventional weathering (Arizona, Florida).The properties determined after exposure are lumi-nous transmittance, chromaticity coordinates, haze,and appearance.

SAE J1545: A Society of Automotive Engineersrecommended practice for instrumented color dif-ference measurement against reference standards forexterior finishes such as topcoat paints, interior tex-tiles, and colored exterior and interior hard trimsused in motor vehicles. The color is measured witha spectrophotometer or colorimeter that meets tospecified requirements. The color difference is deter-mined using lightness, chroma, and hue differencescales.

SAE J1885: A Society of Automotive Engineersrecommended practice for accelerated exposure ofautomotive interior trim components to determinetheir colorfastness using a water-cooled xenon-arclamp apparatus. The lamp is equipped with quartzinner and borosilicate outer filters. The amount ofheat, relative humidity, and irradiance are controlledto simulate the extreme conditions that may existinside a motor vehicle.Alternating irradiation is usedwith a 3.8-hour light cycle (black panel temperature89◦C, relative humidity 50%) and a 1.0-hour dark

436 The Effects of UV Light and Weather on Plastics and Elastomers

cycle (38◦C, 95%). The fading of the specimens isevaluated visually using gray scale or instrumentallyby measuring color difference values.

SAE J1960: A Society of Automotive Engineersstandard test method for accelerated exposure ofautomotive exterior materials to determine theircolorfastness using a water-cooled xenon-arc lampapparatus. The lamp is equipped with quartz innerand borosilicate outer filters. The amount of heat,moisture (humidity, condensation, or rain), andirradiance are controlled to simulate the extremeconditions that may exist outside a motor vehi-cle. Alternating irradiation is used with a 2.0-hourlight cycle (black panel temperature 70◦C, relativehumidity 50%), including 20 minutes with waterspray, and a 1.0-hour dark cycle (38◦C, 95%) withcondensation. The fading of the specimens is eval-uated visually using gray scale or instrumentally bymeasuring color difference values.

SAE J1961: A Society of Automotive Engineersstandard test method for accelerated outdoor expo-sure of automotive exterior materials using a solarFresnel-reflector apparatus to simulate extreme envi-ronmental conditions encountered outside a vehicledue to sunlight, heat, and moisture (as humidity, con-densation, or rain). The flat Fresnel mirrors of theapparatus focus direct sunlight onto an air-cooledspecimen area. The apparatus can be either backed orunbacked and is equipped with a water spray device.Spraying, when used, is done during the night onlyfor 3 minutes at a time with 12-minute dry inter-vals. The report includes exposure time and radiantexposure.

SAE J1976: A Society of Automotive Engineersstandard test method for outdoor weathering ofexterior automotive materials such as coatings fordetermination of their weatherability. The methodspecifies the exposure racks, black boxes, and instru-mentation. In ProcedureA, test racks with or withoutbacking are positioned at a fixed angle of 5 from thehorizontal facing due south. In Procedure B, speci-mens are exposed in a similarly positioned unheatedblack. The conditions of the test are recorded by mea-suring maximum and minimum temperatures andrelative humidity values, hours of wetness, and totaland UV radiant energy.

SAE J2020: A Society of Automotive Engineersstandard test method for accelerated exposure ofautomotive exterior components using a fluorescentUV lamp and condensation apparatus to simulateextreme environmental conditions on the outside ofan automobile due to sunlight, heat, humidity, etc.,to predict the performance of exterior materials suchas topcoat paint. The condensation in the apparatusis achieved by evaporation of water from a heatedpan and exposure of the back sides of the specimensto the cooling effect of ambient air. The specimensare irradiated for 8 hours at 70°C, alternating with4-hour condensation exposure at 50◦C.

SAE J2212: A Society of Automotive Engineersrecommended practice for accelerated exposure ofautomotive interior trim components to determinetheir colorfastness using an air-cooled xenon-arclamp apparatus. The lamp is equipped with a Suprax1/3 filter system. The amount of heat, relative humid-ity, and irradiance are controlled to simulate theextreme conditions that may exist inside a motorvehicle. Alternating irradiation (irradiance 80 W/m2

at 300–400 nm wavelength) is used with a light cycle(chamber temperature 62◦C, relative humidity 50%)and a dark cycle (38◦C, 95%). The fading of thespecimens is evaluated visually using gray scale orinstrumentally by measuring color difference values.

SAE J2230: A Society of Automotive Engineersstandard test method for accelerated exposure ofautomotive interior trim materials using outdoorunderglass sun-tracking temperature and humidityapparatus in which the temperature is controlled ina 24-hour cycle and the humidity is controlled dur-ing the dark (night) portion of the cycle. The test isdesigned to simulate extreme environmental condi-tions encountered inside a vehicle due to sunlight,heat, and humidity to determine the colorfastnessof interior materials such as textiles. The speci-men cabinet is covered with 3-mm thick temperedsafety glass, maintained facing direct sunlight, andequipped with heaters, humidifiers, UV radiometers,sensors, and a controller. The temperature is main-tained at 70◦C during the day and at 38◦C (at 75%relative humidity) during the night. The fading of thespecimens is evaluated visually using gray scale orinstrumentally by measuring color difference values.

SAN: See styrene-acrylonitrile copolymer.

Glossary of Terms 437

SAN copolymer: See styrene-acrylonitrilecopolymer.

SAN resin: See styrene-acrylonitrile copolymer.

scorching: Premature vulcanization of rubber dur-ing processing (e.g., on a calender). Resistance ofrubber to scorching is tested by heating it whilesubjecting to shear (e.g., in Mooney viscometer)for a certain period of time. Also called scorch,prevulcanization.

service life: The period of time required for thespecified properties of the material to deteriorateunder normal use conditions to the minimum allow-able level with the material retaining its overallusability.

shelf life: Time during which a physical system,such as a material, retains its storage stability underspecified conditions. Also called storage life.

short wavelength cutoff: Selectively filtering theradiation from artificial light sources to cut it offin the short UV wavelength region below approxi-mately 300 nm to simulate sunlight.Also called solarcutoff.

shortwave UV radiation: On earth’s surface, elec-tromagnetic radiation in the 315–280 nm wavelengthregion (UV-B) of the solar spectrum. In outer space,radiation in the 280–100 nm wavelength region(UV-C). Also called shortwave UV.

shortwave UV: See shortwave UV radiation.

silicone: These are rigid thermoplastic and liquidsilicones and silicone rubbers consisting of alter-nating silicon and oxygen atom chains with organicpendant groups, prepared by hydrolytic polyconden-sation of chlorosilanes, followed by cross-linking.Silicone rubbers have good adhesion, flexibility,dielectric properties, weatherability, barrier prop-erties, and heat and fire resistance, but decreasedstrength. Rigid silicones have good flexibility,weatherability, soil repelling properties, dimen-sional stability, but poor solvent resistance. Pro-cessed by coating, casting, injection compression,and transfer molding. Used in coatings, electronic

devices, diaphragms, medical products, adhesives,and sealants. Also called siloxane.

siloxane: See silicone.

silver streaks: Scars or surface defects on injectionmoldings caused by the high velocity injection ofa stream of molten material into the mold ahead ofthe normally advancing material front and its prema-ture solidification. Also similar appearance defectsresulting from exposure or stress. Also called silverstreaking, splay marks.

SMA: See styrene-maleic anhydride copolymer.

SMA PTB alloy: See styrene-maleic anhydridecopolymer PBT alloy.

softening point: Temperature at which the mate-rial changes from rigid to soft or exhibits a suddenand substantial decrease in hardness. Also calledsoftening temperature, softening range.

softening range: See softening point.

softening temperature: See softening point.

solar cutoff: See short wavelength cutoff.

solar radiation: Electromagnetic radiation withwavelengths ranging from 1 × 10−9 cm to 30 kmemitted by the sun. The intensity of solar radi-ation in the short UV wavelength region of thespectrum changes from outer space to the earth’s sur-face because of the absorption of UV light belowapproximately 295 nm by the ozone layer of theatmosphere.

splay marks: See silver streaks.

stability: The ability of a physical system, such asa material, to resist a change or degradation underexposure to outside forces, including mechanicalforce, heat, and weather. See also degradation.

starch: A polysaccharide, consisting of amyloseand amylopectin, found in plants such as pota-toes. Gels in water. Used in adhesives, textile sizes,

438 The Effects of UV Light and Weather on Plastics and Elastomers

thickeners, and in the manufacture of biodegrad-able polymers such as polyesters. The grades includetechnical and edible.

starch-modified low density polyethylene: Bio-degradable thermoplastic starch-grafted low densitypolyethylene.

starch-modified polypropylene: Biodegradable ther-moplastic starch-grafted polyurethane.

starch-modified polyurethane: Biodegradable ther-moplastic starch-grafted polyurethane.

static strip test: An ozone resistance test for rubbersthat involves a strip-shaped specimen mounted as atest board, stretched to 15%, and subjected to ozoneattack in the test chamber. The results of the test arereported using two digits separated with a virgule.The number before the virgule indicates the numberof quarters of the test strip which showed the cracks.The number after the virgule indicates the size of thecracks in length perpendicular to the length of thestrip.

storage life: See shelf life.

storage stability: The resistance of physical sys-tem, such as a material, to decomposition, deterio-ration of properties, or any type of degradation instorage under specified conditions.

strain: The per unit change, due to force, in the sizeor shape of a body with respect to its original sizeor shape. Note: Strain is nondimensional but is oftenexpressed in terms of length per unit of length orpercentage.

stress cracking: Appearance of external and/orinternal cracks in the material as a result of stressthat is lower than its short-term strength.

stress pattern: Distribution of applied or residualstress in a specimen, usually throughout its bulk.Applied stress is a stress induced by an outside force(e.g., by loading). Residual stress or stress memorymay be a result of processing or exposure. The stresspattern can be made visible in transparent materialsby polarized light.

styrene-acrylonitrile copolymer: SAN resins arethermoplastic copolymers of about 70% styrene and30% acrylonitrile with higher strength, rigidity, andchemical resistance than polystyrene. Characterizedby transparency, high heat deflection properties,excellent gloss, hardness, and dimensional stability.Have low continuous service temperature and impactstrength. Processed by injection molding, extrusion,injection-blow molding, and compression molding.Used in appliances, housewares, instrument lensesfor automobiles, medical devices, and electronics.Also called SAN, SAN resin, SAN copolymer.

styrene-butadiene block copolymer: Thermoplas-tic amorphous block polymer of butadiene andstyrene having good impact strength, rigidity, gloss,compatibility with other styrenic resins, water resis-tance, and processibility. Used in food and displaycontainers, toys, and shrink wrap.

styrene-butadiene copolymer: Thermoplastic poly-mers of butadiene and >50% styrene having goodtransparency, toughness, and processibility. Pro-cessed by extrusion, injection and blow molding,and thermoforming. Used in film wraps, disposablepackaging, medical devices, toys, display racks, andoffice supplies.

styrene-maleic anhydride copolymer: Thermo-plastic copolymer of styrene with maleic anhydridehaving good thermal stability and adhesion, butdecreased chemical and light resistance. Processedby injection and foam molding and extrusion. Usedin auto parts, appliances, door panels, pumps, andbusiness machines. Also called SMA.

styrene-maleic anhydride copolymer PBT alloy:Thermoplastic alloy of styrene-maleic anhydridecopolymer and polybutylene terephthalate havingimproved dimensional stability and tensile strength.Processed by injection molding. Also called SMAPTB alloy.

styrene plastics: See styrenic resins.

styrene polymers: See styrenic resins.

styrenic resins: Styrenic resins are thermoplas-tics prepared by the free-radical polymerization ofstyrene alone or with other unsaturated monomers.

Glossary of Terms 439

The properties of styrenic resins vary widely withtheir molecular structure, attaining the high perfor-mance level of engineering plastics. Processed byblow and injection molding, extrusion, thermoform-ing, film techniques, and structural foam molding.Used heavily for the manufacture of automotiveparts, household goods, packaging, films, tools, con-tainers, and pipes. Also called styrene resins, styrenepolymers, styrene plastics.

styrenic thermoplastic elastomers: Linear orbranched copolymers containing polystyrene endblocks and elastomer (e.g., isoprene rubber) mid-dle blocks. Have a wide range of hardnesses, tensilestrength, and elongation, and good low-temperatureflexibility, dielectric properties, and hydrolytic sta-bility. Processed by injection and blow molding andextrusion. Used in coatings, sealants, impact modi-fiers, shoe soles, medical devices, tubing, electricalinsulation, and auto parts. Also called TES.

sun hour: One sun hour is an accumulated hour dur-ing which the sun is shining with an intensity of 0.823langleys per min (g cal/cm2/min).

sunshine carbon lamp: Open-flame carbon-arclamp equipped with glass filters (e.g., Corex D) tobetter match sunlight. Sunshine lamp emits moreradiant energy in the short UV (260–320 nm) wave-length region than the sun on the earth’s surfaceand therefore can produce unrealistic light exposureresults. However, radiation from the sunshine lamp ismore realistic than that from the enclosed carbon-arclamp.

Suntest: See Suntest CPS.

Suntest CPS: The Suntest CPS (Controlled PowerSystem) is an accelerated weathering chamber oftable-top size with automated control and monitor-ing of temperature and irradiance from an air-cooledxenon-arc tamp with three filter systems: Max UV(high output in short UV wavelength region), Suprax(best sunlight match), and window glass, Cyclingof light and dark periods and a water immersionmodule are available. Produced by Heraeus DSETLaboratories, Inc., Phoenix, Arizona. Also calledSuntest.

Super-Maq: A large apparatus for accelerated out-door weathering equipped with sun-tracking Fresnelmirror-reflecting solar concentrator and water spray.Super-Maq allows testing of the complete compo-nents. Produced by Heraeus DSET Laboratories,Inc., Phoenix, Arizona.

superficial surface oxidation: Oxidation of thematerial surface that is relatively insignificant andis restricted to the thin surface layer of the material.

surface checks: See checking.

surface roughness: Relatively fine spaced surfaceirregularities, the heights, widths, and directions ofwhich establish the predominant surface pattern.

surface tack: Stickiness of a surface of a materialsuch as wet paint when touched.

syndiotactic: A polymer molecule in which pen-dant groups and atoms attached to the main chainare arranged in a symmetrical and recurring fashionrelative to it in a single plane.

synergistic effect: The boosting effect of one sub-stance on the property of another so that the totaleffect of both substances in a mixture is greaterthan the sum of the effects of each substanceindividually synergistic effect of zinc (e.g., thebis(dibutyldithiocarbamate) on the UVabsorption byzinc oxide).

T

tautomeric: Pertaining to tautomerism (i.e., iso-merism in which migration of a hydrogen atomresults in two or more structures called tautomersthat are in equilibrium). For example, enol and ketotautomers of acetoacetate.

tensile elongation: See elongation.

tensile heat distortion temperature: See heatdeflection temperature.

tensile properties: Properties describing the reac-tion of physical systems to tensile stress and strain.See also tensile property tests.

440 The Effects of UV Light and Weather on Plastics and Elastomers

tensile property tests: Names and designations ofthe methods for tensile testing of materials. Alsocalled tensile tests. See also tensile properties.

tensile strain: The relative length deforma-tion exhibited by a specimen in tension. See alsoelongation.

tensile strength: The maximum tensile stress that aspecimen can sustain in a test carried to failure. Note:The maximum stress can be measured at or after thefailure or reached before the fracture, depending onthe viscoelastic behavior of the material. Also calledtensile ultimate strength, ultimate tensile strength,UTS, tensile strength at break, ultimate tensile stress.See also ASTM D638.

tensile strength at break: See tensile strength.

tensile stress: Tensile stress (or tension) is the stressstate leading to expansion; that is, the length of amaterial tends to increase in the tensile direction.In the uniaxial manner of tension, tensile stress isinduced by pulling forces across a bar, specimen,etc. Tensile stress may be increased until the reachof tensile strength, namely the limit state of stress.

tensile tests: See tensile property tests.

tensile ultimate strength: See tensile strength.

terephthalate polyester: Thermoset unsaturatedpolymer of terephthalic anhydride.

TES: See styrenic thermoplastic elastomers.

test methods: Names and designations of materialtest methods. Also called testing methods.

test variables: Terms related to the testing of mate-rials such as test method names.

testing methods: See text methods.

tetrafluoroethylene-propylene copolymer: Ther-mosetting elastomeric polymer of tetrafluoroethy-lene and propylene having good chemical and heatresistance and flexibility. Used in auto parts.

thermal properties: Properties related to theeffects of heat on physical systems such as materialsand heat transport. The effects of heat include theeffects on structure, geometry, performance, aging,stress strain behavior, etc.

thermal stability: The resistance of a physical sys-tem, such as a material, to decomposition, deterio-ration of properties, or any type of degradation instorage under specified conditions.

thermodynamic properties: A quantity that iseither an attribute of the entire system or is a functionof position, which is continuous and does not varyrapidly over microscopic distances, except possiblyfor abrupt changes at the boundaries between phasesof the system. Also called macroscopic properties.

thermoplastic polyesters: Aclass of polyesters thatcan be repeatedly made soft and pliable on heatingand hard (flexible or rigid) on subsequent cooling.

thermoplastic polyurethanes: A class ofpolyurethanes including rigid and elastomeric poly-mers that can be repeatedly made soft and pliableon heating and hard (flexible or rigid) on subsequentcooling.Also called thermoplastic urethanes, TPUR,TPU.

thermoplastic urethanes: See thermoplasticpolyurethanes.

thermoplastic vulcanizate: A thermoplastic elas-tomer with a chemically cross-linked rubbery phase,produced by dynamic vulcanization.

three-membered heterocyclic compounds: Aclassof heterocyclic compounds containing rings thatconsist of three atoms.

three-membered heterocyclic oxygen compounds:A class of heterocyclic compounds containing ringsthat consist of three atoms, one or two of which is anoxygen.

tinctorial strength: Measure of the effectivenesswith which a unit quantity of a pigment or colorantto change the color of a material. Also called tintstrength.

Glossary of Terms 441

tint: See color.

tint strength: See tinctorial strength.

titanium dioxide: A white pigment and opacifyingagent, TiO2, with the greatest hiding power. Existsin two crystal forms: rutile, (with a higher refractiveindex and opacity) and anatase (with a lower refrac-tive index and opacity). Manufactured in bulk bya sulfation process from the mineral ilmenite or bya chlorination process from the mineral rutile. Thepigment is nonmigrating, heat resistant, chemicallyinert, and lightfast. Used widely in paints, rubber,plastics, paper, synthetic fibers, cosmetics, enamelfrits, floor coverings, etc.

total solar irradience: The amount of radiantpower of sunlight integrated over all its wavelengthsper unit area of irradiated surface at point in time. Ameasure of radiation exposure, it is often expressedin the units of watt per square meter (W/m2).

toughness: Property of a material indicating its abil-ity to absorb energy by plastic deformation ratherthan crack or fracture.

TPO: See olefinic thermoplastic elastomers.

TPU: See thermoplastic polyurethanes.

TPU: See urethane thermoplastic elastomers.

TPUR: See thermoplastic polyurethanes.

transition point: See phase transition point.

transition temperature: See phase transitionpoint.

transmittance: The ratio of the light intensity trans-mitted by a body to the incident light intensity.Also called percentage light transmittance, lighttransmission, luminous transmittance, optical trans-mittance, transmittancy, transparency, transparence.

transparency: See transmittance.

transparent pigment: Pigments such as someorganic pigments having low hiding power.

tribasic lead maleate: Asalt of maleic acid. Highlyeffective as heat stabilizer for polymeric materials.Limited to use in applications where toxicity and lackof clarity can be tolerated.

turbidity: The cloudiness in a liquid caused by asuspension of colloidal liquid droplets or fine solids.

U

UHMWPE: See ultrahigh molecular weight poly-ethylene.

ultimate elongation: See elongation.

ultimate tensile strength: See tensile strength.

ultimate tensile stress: See tensile strength.

ultrahigh molecular weight polyethylene: Ther-moplastic linear polymer of ethylene with molecularweight in the millions. Has good wear and chemicalresistance, toughness, and antifriction properties, butpoor processibility. Processed by compression mold-ing and ram extrusion. Used in bearings, gears, andsliding surfaces. Also called UHMWPE.

ultramarine blue: An inorganic blue pigment withgood alkali and heat resistance, low hiding power,poor acid resistance, and weatherability. Prepared byheating a mixture of sulfur, clay, alkali, and a reduc-ing agent. Used in coatings, inks, rubber, and laundryblues. In low concentration can neutralize yellow tintof white or clear materials.

unbacked exposure rack: A rack for holding spec-imens or specimen panels during exposure testingthat is not enclosed from the back.

units of measurement: Systematic and nonsystem-atic units for measuring physical quantities, includ-ing metric and US pound-inch systems. Also calledunits.

urea resins: Thermosetting polymers of formalde-hyde and urea having good clarity, colorability,scratch, fire, and solvent resistance, rigidity, dielec-tric properties, and tensile strength, but decreasedimpact strength and chemical, heat, and moisture

442 The Effects of UV Light and Weather on Plastics and Elastomers

resistance. Must be filled for molding. Processedby compression and injection molding, impregna-tion, and coating. Used in cosmetic containers,housings, tableware, electrical insulators, countertoplaminates, adhesives, and coatings.

urethane polymers: See polyurethanes.

urethane resins: See polyurethanes.

urethane thermoplastic elastomers: Block poly-ether or polyester polyurethanes containing soft andhard segments. Have good tensile strength, elon-gation, adhesion, and broad hardness and servicetemperature ranges, but decreased moisture resis-tance and processibility. Processed by extrusion,injection molding, film blowing, and coating. Used intubing, packaging film, adhesives, medical devices,conveyor belts, auto parts, and cable jackets. Alsocalled TPU.

urethanes: See polyurethanes.

UTS: See tensile strength.

UV: See UV radiation.

UV absorber: A low-molecular weight organiccompound such as hydroxybenzophenone deriva-tives that is capable of absorbing significant amountof radiant energy in the UV wavelength region, thusprotecting the material such as a plastic in which it isincorporated from the damaging (degrading) effectof the energy. The absorbed energy is dissipated bythe UVabsorber without significant chemical changevia tautomerism of hydrogen bonds. Also called UVstabilizer.

UV filter: Glass filters that selectively transmit(UV-bandpass filters) or block (longpass filters) UVlight. Also called UV filters.

UV filters: See UV filter.

UV light: See UV radiation.

UV radiation: Electromagnetic radiation in thewavelength range 13–400 nm below the short wave-length limit of visible light. The sun is the mainnatural source of UV radiation on the earth.Artificial

sources are many, including fluorescent UV lamps.UV radiation causes polymer photodegradation andother chemical reactions. Note: UV light comprises asignificant portion of the natural sunlight.Also calledultraviolet light, UV, UV light, UV radiation.

UV stabilizer: See UV absorber.

UV wavelength: Any wavelength in the 13–400 nmwavelength region of electromagnetic radiation.

UV-A radiation: A portion of UV radiation in the315–400 nm wavelength range. Causes polymerdamage.

UV-B radiation: A portion of UV radiation in the280–315 nm wavelength range. Includes the shortestwavelengths of sunlight found at the earth’s surface.Causes severe polymer damage; absorber by windowglass.

UV-C radiation: A portion of UV radiation in the100–280 nm wavelength range. A part of sunlightspectra found only in outer space because of theabsorption by the earth’s atmosphere. Germicidal.

UV-CON: See fluorescent UV lamp-condensationapparatus.

UVA-340 lamp: Afluorescent lamp with peak emis-sion at 340 nm that provides high UV-A radia-tion output for accelerated indoor lightfastness andweatherability testing of materials such as plastics,nonmetallic coatings, and textiles. The lamp matchesclosely the sunlight spectrum in the UV wavelengthregion.

UVB-313 lamp: Afluorescent lamp with peak emis-sion at 313 nm that provides high UV-B radia-tion output for accelerated indoor lightfastness andweatherability testing of materials such as plastics,nonmetallic coatings, and textiles. The lamp does notmatch closely the sunlight spectrum in the short UVwavelength region. Used for testing of automotivematerials. Its output is more stable and higher thanthat of the FS-40 lamp.

Glossary of Terms 443

V

veneer: In the rubber industry, a thin film appliedon a rubber article to protect it against oxygen andozone attack. Acts as a migration barrier or is usedfor decorative purposes.

Vicat softening point: The temperature at which aflat-ended needle of prescribed geometry will pen-etrate a thermoplastic specimen to a certain depthunder a specified load using a uniform rate of tem-perature rise. Note: The Vicat softening point isdetermined according to the ASTM D1525 test forthermoplastics such as polyethylene that have nodefinite melting point. Also called Vicat softeningtemperature.

Vicat softening temperature: See Vicat softeningpoint.

vinyl ester resins: Thermosetting acrylated epoxyresins containing styrene reactive diluent. Curedby catalyzed polymerization of vinyl groups andcross-linking of hydroxy groups at room or ele-vated temperatures. Have good chemical, solvent,and heat resistance, toughness, and flexibility, butshrink during cure. Processed by filament winding,transfer molding, pultrusion, coating, and lamina-tion. Used in structural composites, coatings, sheetmolding compounds, and chemical apparatus.

vinyl resins: Thermoplastics polymers of vinylcompounds such as vinyl chloride or vinyl acetate.Have good weatherability, barrier properties, andflexibility, but decreased solvent and heat resistance.Processed by molding, extrusion, and coating. Usedin films and packaging.

vinyl thermoplastic elastomers: Vinyl resin alloyshaving good fire and aging resistance, flexibility,dielectric properties, and toughness. Processed byextrusion. Used in cable jackets and wire insulation.

vinylidene fluoride-hexafluoropropylene copoly-mer: Thermoplastic polymer of vinylidene fluo-ride and hexafluoropropylene having good antistick,dielectric, and antifriction properties, and chemi-cal and heat resistance, but decreased mechanicalstrength and creep resistance and poor processibil-ity. Processed by molding, extrusion, and coating.

Used in chemical apparatus, containers, films, andcoatings.

vinylidene fluoride-hexafluoropropylene-tetra-fluoroethylene terpolymer: Thermosetting elas-tomeric polymer of vinylidene fluoride, hexafluo-ropropylene, and tetrafluoroethylene having goodchemical and heat resistance and flexibility. Used inauto parts.

vulcanizate: Rubber that has been irreversiblytransformed from predominantly plastic to predom-inantly elastic material by vulcanization (chemicalcuring or cross-linking) using heat, vulcanizationagents, accelerants, etc.

vulcanizate cross-links: Chemical bonds formedbetween polymeric chains in rubber as a result ofvulcanization.

W

warpage: See warping.

warping: Dimensional distortion or deviation fromthe intended shape of a plastic or rubber article as aresult of nonuniform internal stress (e.g., caused byuneven heat shrinkage). Also called warpage.

water swell: Expansion of material volume as aresult of water absorption.

watt: One watt is 0.07 gram calories per minute.

weatherometer: An apparatus for acceleratedindoor testing of weatherability of materials such asplastics. Equipped with carbon- or xenon-arc lampshaving glass filters to simulate the sunlight and witha water spraying device. Most models allow control-ling and monitoring temperature and humidity insidethe apparatus as well as alternating dark and lightcycles of exposure.

wet bulb depression: The difference between thetemperatures shown by the wet and dry thermome-ters of a psychrometer, an instrument for measuringthe content of moisture (humidity) in the air.

whiting: A finely divided form of calcium car-bonate (CaCO3) obtained by milling high-calcium

444 The Effects of UV Light and Weather on Plastics and Elastomers

limestone, marble, shell, or chemically precipitatedcalcium carbonate. Used as an extender filler inplastics and rubbers.

X

xenon arc lamp: An inert gas xenon-filled quartztube with two electrodes to produce an electric arcdischarge that emits radiation in the 200–1200 nmwavelength region. Can be air- or water-cooled.Equipped with glass filters to selectively block shortwavelength UV light to simulate sunlight. Usuallythere are two filters—inner and outer—one of whichis made of borosilicate glass. In the water-cooledlamps, cooling demineralized water flows betweenthe inner and outer filters. Used in the apparatusfor accelerated indoor testing of weatherability andlightfastness of materials, these lamps produce morerealistic degradation than carbon arc lamps. Alsocalled xenon lamp.

xenon arc weatherometer: An apparatus for accel-erated indoor testing of weatherability of materialssuch as plastics. Equipped with one or three water-or air-cooled xenon arc lamps with borosilicate glassfilters to simulate sunlight and with a water spray-ing device. Produces more realistic degradation thatcarbon arc weatherometers. Most models allow con-trolling and monitoring temperature and humidityinside the apparatus as well as alternating dark andlight cycles of exposure. Among the manufacturesofxenon arc weatherometers is Atlas Electric DevicesCo., Chicago, Illinois. The Atlas Ci65 model has atwo-tier inclined specimen rack with the xenon-arclamps located vertically at the central axis of theracks. Also called Ci65 xenon arc weatherometer,Atlas Ci65 xenon arc weatherometer.

xenon lamp: See xenon arc lamp.

Xenotest 1200: A computerized chamber for accel-erated weatherability testing of materials manufac-tured by Heraeus DSET Laboratories, Inc., Pheonix,Arizona. Equipped with three air-cooled xenon-arclamps, an optical filter system for selectively block-ing UV light, rotating specimen holders, a samplespray system, specimen back side cooling for dewsimulation, rain water heating system, and con-trol systems for irradiance, temperature, speed, andhumidity of inside air.

Y

yellowing: Developing of yellow color in near-white or near-transparent materials such as plasticsor coatings as a result of degradation on exposureto light, heat aging, weathering, etc. It is usuallymeasured in terms of yellowness index.

yellowness index: A measure of the tendency ofmaterials such as plastics to become yellow as aresult of long-term exposure to light, irradiation, etc.

Z

zinc oxide: An amorphous white powder, ZnO,used as a pigment in plastics and coatings, as anactivator of rubber vulcanization accelerators, andas reinforcing filler. Having the greatest UV lightabsorbing power of all commercially available pig-ments, it can act as a UV stabilizer, especiallyin synergistic mixtures with organics such as zincbis(dibutyldithiocarbamate).

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149. Novatec Novaloy 9000, supplier marketingliterature, Novatec Plastics & Chemicals Co.

150. Supplier Written Correspondence, KleerdexCompany, 1994.

151. Bayblend FR Resins for Business Machinesand Electronics, supplier marketing literature (55-D808(5)J 313 10/88), Mobay Corporation, 1988.

152. Pulse 1745 Polycarbonate/ABS Resin ForComputer And Business Equipment, supplier mar-keting literature (301-00425-793 SMG), DowChemical Company, 1993.

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155. Chapman, G., New Technologies And Appli-cations For Starch Containing Degradable Plastics,supplier technical report, Ecostar International L.P.

156. MaterBi, Novamont.com 2005.

157. Rapidcoat, 2005. http://www.rapidcoat.com/Guidelines.htm

158. Powder Coaters Manual, 2005. http://www.coatings.de/pcmanual/manual/kap1-2.pdf

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Trade Name Index

Advanced Elastomer SystemsSantoprene—Chapter 62

American CyanamidTMXDI (META)—Chapter 76

ArkemaKynar—Chapter 12

AtoglasPlexiglas—Chapter 5

AusimontDutral-TER—Chapter 72

BASFCapron—Chapter 20Elastollan—Chapter 66Luran—Chapter 1, 4, 49Polystyrol—Chapter 45Styrolux—Chapter 64Terluran—Chapter 1Ultradur—Chapter 29Ultraform—Chapter 3Ultramid—Chapter 20, 22, 24Ultrason—Chapter 48

BayerBayblend—Chapter 55

Chevron PhillipsMarlex—Chapter 39Ryton—Chapter 44K-Resin—Chapter 50

CyroAcrylite—Chapter 5Cyrolon—Chapter 5

DowCalibre—Chapter 27Engage—Chapter 62Pellethane—Chapter 66Pulse—Chapter 55Styron—Chapter 46Tyril—Chapter 49Tyrin—Chapter 61

Dow CorningSilastic—Chapter 77

DuPontDelrin—Chapter 3Hypalon—Chapter 70Hytrel—Chapter 63Kapton—Chapter 33Kevlar—Appendix 1Neoprene—Chapter 73Nordel—Chapter 72Rynite—Chapter 30Surlyn—Chapter 17Tedlar—Chapter 16, Appendix 1Teflon—Chapter 9, Appendix 1Tefzel—Chapter 15Zytel—Chapter 23

EastmanTenite—Chapter 7

EliokemChemigum—Chapter 67

EMS GrivoryGrilamid—Chapter 21

ExxonVistalon—Chapter 72

GE PlasticsCycolac—Chapter 1, 2Cycoloy—Chapter 28Geloy—Chapter 2, 4Lexan—Chapter 27Noryl—Chapter 18Ultem—Chapter 35

GoodyearNatsyn—Chapter 75

HoneywellAclar—Chapter 13

Japan Synthetic Rubber CompanyJSR BR—Chapter 74

454 The Effects of UV Light and Weather on Plastics and Elastomers

Laporte AlphaGaryEvoprene—Chapter 65

LNP Engineering PlasticsGeneral Purpose Polystyrene—Chapter 45Nylon 6/6—Chapter 22Nylon 6—Chapter 20Polycarbonate—Chapter 27Polyethylene—Chapter 37Polypropylene—Chapter 42Polysulfone—Chapter 47

LuciteTufcoat—Chapter 6

MitsubishiIupital—Chapter 3Rayon—Chapter 4Reny—Chapter 25

Mitsui ChemicalsTPX—Chapter 43

NOVA ChemicalsStyrosun—Chapter 46

NovacorNAS—Chapter 5Zylar—Chapter 5

NovamontMater-Bi—Chapter 57

NovatecKydex—Chapter 54Novaloy—Chapter 53

NoveonEstane—Chapter 66

PolimeriDutral—Chapter 71

PolyOneForprene—Chapter 62Geon—Chapter 51

RecticelColo-Fast—Chapter 59, 76

Shell ChemicalKraton—Chapter 65

Solvay Advanced PolymersIXEF—Chapter 26Torlon—Chapter 34

Solvay PlasticsUdel—Chapter 47

Solvay SolexisHalar—Chapter 12, 14Hylar—Chapter 12Solef—Chapter 12

TiconaCelanex—Chapter 29Celcon—Chapter 3GUR—Chapter 40Hostaform—Chapter 3Vectra—Chapter 31

UbeNylon 6—Chapter 20Upilex—Chapter 33Upimol—Chapter 33

United CoatingsElastuff—Chapter 76

VictrexVictrex PEEK—Chapter 36

WestlakeArdel—Chapter 32

Plastics Design Library

Founding Editor: William A. Woishnis

Fluorinated Coatings and Finishes Handbook: TheDefinitive User’s Guide and Databook, LaurenceW. McKeen, 978-0-8155-1522-7, 400 pp., 2006

Fluoroelastomers Handbook: The Definitive User’sGuide and Databook, Albert L. Moore, 0-8155-1517-0, 359 pp., 2006

Reactive Polymers Fundamentals and Applica-tions: A Concise Guide to Industrial Polymers,J.K. Fink, 0-8155-1515-4, 800 pp., 2005

Fluoropolymers Applications in Chemical Process-ing Industries, P. R. Khaladkar, and S. Ebnesajjad,0-8155-1502-2, 592 pp., 2005

The Effect of Sterilization Methods on Plastics andElastomers, 2nd Ed., L. K. Massey, 0-8155-1505-7, 408 pp., 2005

Extrusion: The Definitive Processing Guide andHandbook, H. F. Giles, Jr., J. R. Wagner, Jr.,and E. M. Mount, III, 0-8155-1473-5, 572 pp.,2005

Film Properties of Plastics and Elastomers, 2nd Ed.,L. K. Massey, 1-884207-94-4, 250 pp., 2004

Handbook of Molded Part Shrinkage and Warpage,J. Fischer, 1-884207-72-3, 244 pp., 2003

Fluoroplastics, Volume 2: Melt-Processible Fluoro-plastics, S. Ebnesajjad, 1-884207-96-0, 448 pp.,2002

Permeability Properties of Plastics and Elastomers,2nd Ed., L. K. Massey, 1-884207-97-9, 550 pp.,2002

Rotational Molding Technology, R. J. Crawford andJ. L. Throne, 1-884207-85-5, 450 pp., 2002

Specialized Molding Techniques & Application,Design, Materials and Processing, H. P. Heim,and H. Potente, 1-884207-91-X, 350 pp., 2002

Chemical Resistance CD-ROM, 3rd Ed., PlasticsDesign Library Staff, 1-884207-90-1, 2001

Plastics Failure Analysis and Prevention, J. Moalli,1-884207-92-8, 400 pp., 2001

Fluoroplastics, Volume 1: Non-Melt ProcessibleFluoroplastics, S. Ebnesajjad, 1-884207-84-7,365 pp., 2000

Coloring Technology for Plastics, R. M. Harris, 1-884207-78-2, 333 pp., 1999

Conductive Polymers and Plastics in IndustrialApplications, L. M. Rupprecht, 1-884207-77-4,302 pp., 1999

Imaging and Image Analysis Applications for Plas-tics, B. Pourdeyhimi, 1-884207-81-2, 398 pp.,1999

Metallocene Technology in Commercial Applica-tions, G. M. Benedikt, 1-884207-76-6, 325 pp.,1999

Weathering of Plastics, G. Wypych, 1-884207-75-8,325 pp., 1999

Dynamic Mechanical Analysis for Plastics Engi-neering, M. Sepe, 1-884207-64-2, 230 pp., 1998

Medical Plastics: Degradation Resistance and Fail-ure Analysis, R. C. Portnoy, 1-884207-60-X,215 pp., 1998

Metallocene Catalyzed Polymers, G. M. Benediktand B. L. Goodall, 1-884207-59-6, 400 pp.,1998

Polypropylene: The Definitive User’s Guide andDatabook, C. Maier and T. Calafut, 1-884207-58-8, 425 pp., 1998

Handbook of Plastics Joining, Plastics DesignLibrary Staff, 1-884207-17-0, 600 pp., 1997

Fatigue and Tribological Properties of Plasticsand Elastomers, Plastics Design Library Staff,1-884207-15-4, 595 pp., 1995

Chemical Resistance, Vol. 1, Plastics Design LibraryStaff, 1-884207-12-X, 1100 pp., 1994

456 The Effects of UV Light and Weather on Plastics and Elastomers

Chemical Resistance, Vol. 2, Plastics Design LibraryStaff, 1-884207-13-8, 977 pp., 1994

The Effect of UV Light and Weather on Plastics andElastomers, 1st Ed., Plastics Design Library Staff,1-884207-11-1, 481 pp., 1994

The Effect of Creep and Other Time Related Fac-tors on Plastics and Elastomers, Plastics DesignLibrary Staff, 1-884207-03-0, 528 pp., 1991

The Effect of Temperature and Other Factors onPlastics, Plastics Design Library Staff, 1-884207-06-5, 420 pp., 1991