Polymers in simple

POLYMER

WHAT IS POLYMER? POLYMER IS A MARCOMOLECULE WHICH

ARE JOINED TOGTHER BY SMALL MOLECULE.

EXAMPLE: POLYETHYLENE HEAT n CH2=CH2 (CH-CH2)

ETHYLENE CATALYST POLYETYLENE

CHARACTERISTICS OF POLYMER

LOW DENSITY

GOOD MOULDABILITY

GOOD CORROSION RESISTANCE

POOR TENSILE STRENGTH

LOW MECHANICAL PROPERTIES

POOR TEMPERATURE RESISTANCE

CLASSIFICATION OF POLYMER

POLYMERS ARE MAINLY CLASSIFIED INTO TWO TYPES

NATURAL POLYMER SYNTHETIC POLYMER

NATURAL POLYMER

NATURAL POLYMER ARE THE POLYMER EXIST AS NATURAL RESOURCE

SUCH AS CELLOUSE WHICH IS THE MAIN CONSITUTENT OF WOOD AND PAPER.

EXAMPLES:CELLOUSE AMINO ACIDS etc..,

SYNTHETIC POLYMER

POLYMER MADE BY ARTIFICIALLY USING CHEMICAL ARE CALLED AS SYNTHETIC POLYMERS.

EXAMPLE:BAKELITE NEOPRENE NYLON

POLYVINYL CHOLRIDE POLYSTYRENE

NYLON 6-6

IT IS OTBTAINED BY POLYMERIZATION OF HEXAMETHYLENE DIAMINE AND ADIPIC ACID.

PROPERTIES

NYLON 6:6 IS LESS SOFT AND STIFF MATERIAL.

THEY BEHAVE AS PLASTIC AS WELL AS FIBER.

THAY HAVE GOOD MECHANICAL STRENGTH.

HIGH ABRASION RESISTANCE.

USES

USED IN FIBERS IN MAKING SCOKS,DRESSES etc.,

USED IN MOULDING PURPOSE FOR MAKING GEAR.

USED FOR MAKING FILAMENTS IN TOOTH BRUSHES.

EPOXY RESIN

IT IS PREPARED BY CONDENSING EPICHLOROHYDRIN WITH BISPHENOL.

PROPERTIES

HIGHLY CHEMICAL RESISTANCE TO WATER,ACIDICS,ALKALIS AND OTHER CHEMICALS.

THEY ARE FLEXIBLE AND TOUGH. POSSES VERY GOOD HEAT RESISTANCE. POSSES EXCELLENT ADHESION

QUALITY.

USES

EPOXY RESIN ARE USED AS SURFACE COATINGS AND ADHESIVE.

USED AS LAMINATING MATERIAL IN ELECTRICAL EQUIPMENTS.

USED FOR THE PRODUCTION OF COMPONENTS FOR AIRCRAFTS AND AUOTMOBLIES.

MECHANISM OF ADDITION POLYMERIZATION

IT CAN BE EXPLAINED BY THE TWO FOLLOWING METHODS

FREE RADICAL

MECHANISM IONIC RADICAL

MECHANISM

FREE RADICAL

IT OCCURS IN THREE STEPS INITIATION PROPAGATION TERMINATION

INTIATION PRODUCTION OF FREE RADICAL BY

HOMOLYTIC DISSOCIATION. I 2R0

INTIATOR FREE RADICAL

ADDITION OF FREE RADICAL TO THE FIRST MONOMER.

PROPAGATION GROWTH OF CHAIN INTIATING

SPECIES

TERMINATION COUPLING INVOLVES COUPLING OF FREE RADICAL

ONE CHAIN END TO ANOTHER.

DISPROPORTIONATION INVOLVES TRANSFER OF HYDROGEN

ATOM OF ONE RADICAL CENTRE TO ANOTHER,FORMING SATURATED AND UNSATURATED MOLECULE.

IONIC MECHANISN

IT IS INITIATED BY A POSITIVE ION AND NEGATIVE ION.

CATIONIC

POLYMERIZATION ANIONIC POLYMERIZATION

CATIONIC POLYMERISATION

IT TAKES PLACE WHEN ELECTRON DONATING GROUPS LIKE PRESENT IN MONOMER.

THESE GROUPS STABILISE THE CABONIUM ION FORMATION.

STYRENEINTIATOR USED TO INTIATE THE REACTION

ARELEWIS ACIDS()

INTIATOR

PROPAGATION IT INOLVES THE GROWTH OF CHAIN

INITIATING SPECIES.

TERMINATION IT INVOLVES THE REMOVAL OF

CATALYST BY THE ADDITION OF PROTON

ANIONIC POLYMERIZATION

IT TAKE PLACE WHEN ELECTRON WITHDRAWING

GROUP LIKE ()PRESENT IN MONOMER.

THESE GROUP STABILISE CARBANION FORMATION.

ACRYLONITRILEINITIATOR USED TO INITIATE THE

REACTION ARE LEWIS BASES LIKE()

INTIATIONIT INVOLVES THE FORMATION OF CHAININITIATING SPECIES.

PROPAGATION IT INVOLVES THE GROWTH OF CHAIN

INTIATING SPECIES.

TERMINATION IT OCCURS BY ADDING AMMONIA.

Presented by dhayanidhi.e gokul.s amarnath.aMUTHAYAMMAL ENGINEERING COLLEGE RASIPURAM NAMAKKAL