Effect of Salicylic Acid / Ethanol Treatment on Tensile Properties and Morphology Analysis of Recycled High Density Polyethylene / Wood Fiber Composites

Effect of Isophthalic Acid-Maleic Anhydride (IAMA) as a Compatibilizer

on Tensile Properties and Swelling Behavior of Ethylene Vinyl Acetate

(EVA)/ Natural Rubber (NR)/ Potash Feldspar Composites

S. H. Ho 1, a, Supri A. Ghani 2, b, P.L. Teh3, c

1, 3School of Materials Engineering, Universiti Malaysia Perlis (UniMAP), Kompleks Taman Muhibah, Jejawi 2, 02600, Perlis, Malaysia

2Faculty of Engineering Technology, Universiti Malaysia Perlis (UniMAP), Main Campus, Pauh

Putra, Perlis, Malaysia

aEmail: [email protected] bEmail: [email protected] cEmail: [email protected]

Keywords: Feldspar, ethylene vinyl acetate, natural rubber, isophathalic acid, maleic anhydride

Abstract: The effect of isophathalic acid-maleic anhydride (IAMA) as a compatibilizer on the

tensile properties and swelling behavior of ethylene vinyl acetate /natural rubber/ feldspar

(EVA/NR/PF) composites were studied. The EVA/NR/PF composites with and without IAMA

were prepared using Brabender Plasticoder at 160ºC with 50rpm rotor speed. The results indicated

that EVA/NR/PF/IAMA showed higher value of tensile strength and M100 but lower elongation at

break and percentage mass swell compared to EVA/NR/PF composites.

Introduction

Thermoplastic elastomers (TPEs) are defined as materials which combining amorphous

elastomeric components and polyolefin semi-crystalline thermoplastic. Ethylene vinyl acetate

(EVA) consists of copolymer of ethylene and vinyl acetate. TPEs can be processed by thermoplastic

processing equipment and it shows rubber-like properties [1].

EVA is produced by free-radical polymerization in a high-pressure polyethylene (HPPE)

process [2]. The properties of EVA are low temperature resistance, excellent flexibility, optical

properties and impact resilience. EVA is widely used in electrical cable sheathing and packing film

[3]. EVA contents affect the thermal and rheological properties [4].

Poor interfacial adhesion caused by the incompatibility of the matrix can be improved by the

addition of the compatibilizers. The function of maleic anhydride (MAH) as compatibilizers can

improve the poor adhesion between the matrixes [5]. Kord [5] studied the influence of maleic

anhydride on the flexural, tensile and impact characteristics of sawdust flour reinforced

polypropylene composite. He found that with addition of maleic anhydride, the interface adhesion

of sawdust flour and polypropylene phases were improved.

Obele et al. [6] studied the effects of maleic anhydride on the mechanical properties and

morphology of wheat straw fibre reinforced polypropylene. The results indicated that with the

increased in wheat straw fiber content, tensile strength, elongation at break and impact strength

decreased. Besides, the mechanical properties were improved with the incorporation of maleic

anhydride. In this paper, the effect of IAMA as a compatibilizer on tensile properties and swelling

behaviour of ethylene vinyl acetate (EVA)/ natural rubber (NR)/ feldspar (PF) composites were

investigated.

Materials

The EVA used was obtained from The Polyolefin Company (Singapore) Pte.Ltd. EVA contains

18.1 wt% VA. The natural rubber (SMR-L) was purchased from Rubber Research Institute of

Applied Mechanics and Materials Vol. 679 (2014) pp 76-80 Submitted: 12.08.2014Online available since 2014/Oct/08 at www.scientific.net Accepted: 13.08.2014© (2014) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMM.679.76

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: 58.27.57.125-09/10/14,04:16:33)

Malaysia (RRIM). Potash Feldspar was obtained from Commercial Minerals (M) Sdn. Bhd.,

Penang, Malaysia. The chemical composition and physical properties of potash feldspar are given in

Table 1. Maleic anhydride and Isophthalic acid were supplied by Zarm Scientific & Supplier Sdn.

Bhd. Penang, Malaysia.

Table 1: Chemical and physical properties of potash feldspar

Chemical Composition Value (%)

SiO 67.0

Al2O3 19.0

CaO 0.11

Na2O 2.3

P2O5 0.18

SO3 0.028

K2O 11.0

Fe2O3 0.12

NiO 0.025

Rb2O 0.28

Ignition loss 0.2

Physical Properties

Mean particle size (µm) 13.6

Surface area (m2/g) 0.73

Density (g/m3) 2.0

The compounding was carried out by melt blending in Brabender Plasticoder. Before the

compounding process starts, the Brabender Plasticorder was set at the temperature of 160˚C and

rotor speed of 50 rpm. The EVA was loaded into the mixing chamber and preheats for 3 minute.

After that, NR was added. The mixing was continued until a constant torque was obtained. Then,

the potash feldspar with IA and MA were added. The total mixing time was 10 minutes. The soften

blend were removed from the chamber and pressed into thick round pieces. The formulations of of

EVA/NR/PF composites and EVA/NR/PF/IAMA composites are shown in Table 2.

Table 2: Formulations of EVA/NR/PF composites and EVA/NR/PF/IAMA composites with

different filler loading

Composite Code EVA/NR

(phr)

Potash Feldspar

(phr)

IA-MA

(phr)

EVA/NR 70/30 - -

EVA/NR/FP-5 70/30 5 - EVA/NR/FP -10 70/30 10 - EVA/NR/FP -15 70/30 15 - EVA/NR/FP -20 70/30 20 -

EVA/NR/FP -25 70/30 25 -

EVA/NR/FP-5/IAMA 70/30 5 6*

EVA/NR/FP-10/IAMA 70/30 10 6*

EVA/NR/FP-15/IAMA 70/30 15 6*

EVA/NR/FP-20/IAMA 70/30 20 6*

EVA/NR/FP-25/IAMA 70/30 25 6*

*IA-MA was added 6 phr in the composites

Results and Discussion

Figure 1 shows the effect of filler loading on tensile strength of EVA/NR/PF and

EVA/NR/PF/IAMA composites. From Figure 1, it can be clearly seen that as the filler loading

increases, the tensile strength decreases for both EVA/NR/PF and EVA/NR/PF/IAMA composites.

Applied Mechanics and Materials Vol. 679 77

This was due to poor interaction and incompatibility of the matrixes. However, EVA/NR/PF/IAMA

composites exhibited higher tensile strength than EVA/NR/PF composites. The good interaction of

hydrogen atoms from ethylene vinyl acetate and C-O of IAMA which formed the hydrogen bonding

enhanced tensile strength and stiffness of the EVA/NR/PF/IAMA composites. The stress transfer at

the filler-polymer interphase was improved. The vinyl group of EVA structure and –COOH groups

from IAMA grafted onto EVA and NR phases which improved the compatibility and interfacial

adhesion between the EVA and NR phases. At a similar observation from Santhoskumar et al. [7]

that improvement in tensile properties had shown with the addition of MAH in Ultra High

Molecular Weight Polyethylene (UHMWPE) - Ethyl Vinyl Acetate (EVA) blends. Ling Zhang et al.

[8] studied aluminium hydroxide filled ethylene vinyl acetate (EVA) composites: effect of the

interfacial compatibilizer and the particle size. They observed that the adhesion of EVA/Alumina

trihydrate (ATH) composites was dramatically increased with the addition of interfacial modifier

which results in the improvement in flammability and tensile strength.

Figure 1: Tensile strength vs filler loading of EVA/NR/PF and EVA/NR/PF/IAMA composites with

different filler loading

Figure 2 shows the effects of filler loading on modulus at 100% elongation (M100) of

EVA/NR/PF composites and EVA/NR/PF/IAMA composites. The M100 for both the EVA/NR/FP

and EVA/NR/PF/IAMA composites shows an increasing trend as the increasing of the filler

loading. This was due to the addition of feldspar increases the stiffness and reduces the ductility of

the composites. The M100 for EVA/NR/PF/IAMA composites indicated higher value compared to

EVA/NR/PF composites. This was due to the increase in the crosslink density and hydrogen

bonding the composites became stiff with the addition of IAMA.

Figure 2: Modulus at 100% elongation vs filler loading of EVA/NR/PF and EVA/NR/PF/IAMA

composites with different filler loading

0

1

2

3

4

5

6

7

8

5 10 15 20 25

Ten

sile

Str

en

gth

(M

Pa)

Filler Loading (phr)

EVA/NR/PF EVA/NR/PF/IAMA

0

0.2

0.4

0.6

0.8

1

1.2

1.4

5 10 15 20 25

M1

00

(M

Pa)

Filler Loading (phr)

EVA/NR/PF EVA/NR/PF/IAMA

78 Engineering and Technology Research

Figure 3 shows the effect of filler loading on the percentage mass swell for EVA/NR/PF

composites and EVA/NR/PF/IAMA composites. From Figure 3, the results indicated that the

percentage mass swell for both composites decreases as the increases of the filler loading. As the

filler loading increased, the resistance for the toluene to penetrate into the composites was greater.

The filler tend to block the penetration of toluene. Besides, the percentage mass swell for

EVA/NR/PF/IAMA composites are lower if compared to EVA/NR/PF composites. As the filler

loading increased, the cross-link density increase which restricted the toluene to swell the

composites. At a similar observation from Supri et al. [9], He reported that the molar sorption of the

LDPE/NR/WHF and LDPE/NR/WHF/PVA composites decreased as the water hyacinth fiber

(WHF) increased. The result indicated that the molar sorption of LDPE/NR/WHF/PVA composites

was slightly lower than LDPE/NR/WHF composites as the WHF loading increased.

Figure 3: Percentage mass swell vs filler loading of EVA/NR/PF composites and

EVA/NR/PF/IAMA composites with different filler loading

Conclusion

As the filler loading increases, tensile strength, elongation at break and percentage mass

swell decreased while M100 increased. The addition of IAMA as compatibilizer for EVA/NR/PF

composites slightly increased the tensile strength, modulus at 100% elongation but slightly

decreased percentage mass swell.

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0

50

100

150

200

250

5 10 15 20 25

Swe

llin

g (%

)

Filler Loading (phr)

EVA/NR/PF EVA/NR/PF/IAMA

Applied Mechanics and Materials Vol. 679 79

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80 Engineering and Technology Research

Engineering and Technology Research 10.4028/www.scientific.net/AMM.679 Effect of Isophthalic Acid-Maleic Anhydride (IAMA) as a Compatibilizer on Tensile Properties and

Swelling Behavior of Ethylene Vinyl Acetate (EVA)/Natural Rubber (NR)/Potash Feldspar Composites 10.4028/www.scientific.net/AMM.679.76