Experimental Testing On Hybrid Composite Materials

Sathish.S1,a , Ganapathy.T2,b , Bhoopathy.T3,c

Department of Mechanical Engineering

1,2,3 PG Scholar, Sri Krishna College of Engineering & Technology, Coimbatore, Tamilnadu, India

asathi175@gmail.com , bganaskctmech@yahoo.in , cbpmech08@gmail.com

Keywords: Sisal, Jute, Glass, Epoxy and Hybrid Composite

Abstract. In recent trend, the most used fiber reinforced composite is the glass fiber composite. The

glass-fiber composites have high strength and mechanical properties but it is costlier than sisal and

jute fiber. Though the availability of the sisal and jute fiber is more, it cannot be used for high

strength applications. A high strength-low cost fiber may serve the purpose. This project focuses on

the experimental testing of hybrid composite materials. The hybrid composite materials are

manufactured using three different fibers - sisal, glass and jute with epoxy resin with weight ratio of

fiber to resin as 30:70. Four combinations of composite materials viz., sisal-epoxy, jute-epoxy,

sisal-glass-epoxy and sisal-jute-epoxy are manufactured to the ASTM (American Society for

Testing and Materials) standards. The specimens are tested for their mechanical properties such as

tensile and impact strength in Universal Testing machine. The results are compared with that of the

individual properties of the glass fiber, sisal fiber, jute fiber composite and improvements in the

strength-weight ratio and mechanical properties are studied.

Introduction

The natural fiber reinforced composites are growing rapidly due to their mechanical properties, low

cost, processing advantages and low density. The availability of natural fibers such as sisal and jute

in Asia is more and also has some advantages over traditional reinforcement materials in terms of

cost, density, renewability, recyclability, abrasiveness and biodegradability. The performance of the

fiber reinforced composites mainly depends on the fiber matrix and the ability to transfer the load

from the matrix to the fiber. Polymeric materials reinforced with synthetic fibers such as glass,

carbon and aramid provide advantages of high stiffness and strength to weight ratio as compared to

conventional construction materials, i.e. wood, concrete and steel. In spite of these advantages, the

widespread use of synthetic fiber-reinforced polymer composite has a tendency to decline because

of their high initial costs and also production of synthetic composites requires a large quantum of

energy and quality of environment suffered because of the pollution generated during the

production and recycling of these synthetic materials.

Objective of the Project

• To find the feasibility of weight and cost reduction of the ‘hybrid composite’ by

reinforcing it with sisal, glass & jute fiber.

• To treat the natural fibers to remove the impurities and increase the properties

• To fabricate the specimens to the ASTM standards using compression molding process for

the following combinations.

1. Sisal + Epoxy

2. Jute + Epoxy

3. Sisal + glass + Epoxy

4. Sisal + jute + Epoxy

Applied Mechanics and Materials Vols. 592-594 (2014) pp 339-343 Submitted: 24.04.2014Online available since 2014/Jul/15 at www.scientific.net Revised: 08.05.2014© (2014) Trans Tech Publications, Switzerland Accepted: 16.05.2014doi:10.4028/www.scientific.net/AMM.592-594.339

All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,www.ttp.net. (ID: 130.207.50.37, Georgia Tech Library, Atlanta, USA-09/12/14,16:17:50)

• To study the strength and properties of the hybrid composite (glass fiber-sisal fiber-jute

fiber) through mechanical tests.

• To compare the results with that of the individual fiber composite.

Work Methodology

Selection of Materials. In this work we have used the synthetic and natural fiber reinforced

plastics. The hybrid composites are used to find out the impact test. The sisal/E-glass reinforced

epoxy is thus used as hybrid composites. The purpose of using E-glass fiber with sisal fiber is to

improve the mechanical properties of natural fiber.

Procedure for Alkali Treatment

• Fiber is dipped in distilled water for 24 hrs and then dried in direct sun light.

• Secondly it is dipped in NaOH solution for 24hrs and then it is dried.

• Finally it is placed in oven for 6hrs.

• This treated fiber is then converted into mat i.e., fabric material.

Fig. 1 Sisal fiber Fig. 2 Sisal fiber in NaOH

Fig. 3 Dried sisal fiber Fig. 4 Sisal fiber in hot air oven

Manufacturing Method

There are various methods to fabricate the composites. They are hand lay-up process, pultrusion

process, filament winding process, resin transfer molding, sheet molding compound, reaction

injection molding. Here we use the compression molding process for the fabrication of hybrid

composites.

Compression Molding Method. Procedure for compression molding

• With the dies apart, the prepared polymer ‘dough’ is placed into the cavity.

• With the die closed, the article is formed and the small amount of flashing on each side will

be removed later.

340 Dynamics of Machines and Mechanisms, Industrial Research

• When the die is closed, heat and pressure are maintained until the condensation

polymerization process is completed.

• The hot compression molding process is used to form components from phenolic, urea and

melamine thermosetting polymers, as well as alkyl resins.

Fig. 5 Compression molding process

Fig. 6 Specimen piece of Hybrid Fig. 7 Specimen piece of jute fiber

Composite (sisal + jute)

The specimen piece manufactured by compression molding process before cutting as per ASTM

standard.

Experimental Tests

The hybrid composite materials sisal-glass-epoxy, sisal-jute-epoxy and sisal-epoxy, jute-epoxy are

to be tested for their mechanical properties. Tensile test, Impact test, Flexural test can be done on

the specimens produced from composites. Here, the specimens cut to ASTM standards from the

manufactured composites are tested to find out the values of tensile strength and impact strength.

The tensile test for two specimen pieces are performed by the universal testing machine Instron

1195 and impact test are performed using Izod impact testing machine.

Universal Testing Machine. The tensile strength of a material is the maximum amount of

tensile stress that it can take before failure. During the test a uni-axial load is applied through both

the ends of the specimen. The dimension of the specimen is (250x25x3) mm. The tensile test is

performed in the universal testing machine (UTM) Instron 1195 and results are analyzed to

calculate the tensile strength of composite samples.

Applied Mechanics and Materials Vols. 592-594 341

Izod Impact Testing Machine. The impact test is for the purpose of knowing the material’s

ability to resist the impact load and the service life of the material. The impact test designed to give

information on how a specimen of a known material will respond to a suddenly applied stress, e.g.

shock. A method for determining behavior of material subjected to shock loading in bending,

tension, or torsion. The Izod test is most commonly used to evaluate the relative toughness or

impact toughness of materials and as such is often used in quality control applications where it is a

fast and economical test. It is used more as a comparative test rather than a definitive test.

Results and Discussion

The specimens are tested for their tensile and impact strength and the following results are obtained.

Fig. 8 Specimen after tensile test

Table 1. Results for four combinations

Combinations Tensile Strength[N/mm

2] Impact Strength[J/mm

2]

Specimen1 Specimen2 Specimen1 Specimen2

Sisal + Epoxy 20.16 21.23 2.734 2.418

Jute + Epoxy 23.36 22.28 3.384 2.937

Sisal + Glass +

Epoxy 49.987 53.55 6.105 6.593

Sisal + Jute +

Epoxy 27.89 25.97 4.641 4.823

The specimens of four different combinations tested for their tensile and impact strength showed

significant results with sisal-glass combination taking the lead in both tests. Though the fibers sisal

and jute have closer tensile strength jute has maximum 23.36 N/mm2. Tensile strength of individual

combination and that with glass fiber makes considerable difference.

As far as impact strength is considered, sisal lags with least value followed by jute. While

combined, sisal-glass stays ahead of sisal-jute by reaching a maximum of 6.593 J/mm2.

342 Dynamics of Machines and Mechanisms, Industrial Research

Conclusion

Based on the results we obtained at the following conclusions. The sisal, jute and glass fibers with

epoxy resin are used to produce the hybrid composite materials with weight ratio of fibers to resin

as 30:70. The use of natural fibers resulted in the reduction of cost and it has no harmful

environmental impact as these are easily biodegradable. In tensile test and impact test, among the

four hybrid composites, sisal-glass-epoxy has high elongation and hence high tensile strength.

Since, it shows results comparable with Glass Fiber Composite, it can be used for similar

applications. By comparing the tensile and impact strength of the composites with that of the other

combinations, sisal-glass-epoxy hybrid shows better properties.

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