Synergistic Effect of EG and Cloisite 15A on the Thermomechanical Properties and Thermal Conductivity of EVA/PCL Blend

Tebello Abel Tsotetsi,Zikhona Linda Linganiso,Mokgaotsa Jonas Mochane,Thandi Patricia Gumede,Tshwafo Elias Motaung

doi:10.1590/1980-5373-mr-2016-0277

Tebello Abel Tsotetsi, Zikhona Linda Linganiso + Show 3 more

Open Access

https://doi.org/10.1590/1980-5373-mr-2016-0277

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Abstract

The purpose of this study was to investigate the synergy of expanded graphite (EG) and Cloisite 15A (C15A) on the thermal conductivity and thermomechanical properties of ethylene-vinyl acetate copolymer/poly ( ɛ-caprolactone) (EVA/PCL) blend. Scanning electron microscopy (SEM) results showed that the blend had a phase separation, in which the PCL phase (appeared as droplets) was dispersed uniformly in the EVA matrix in all samples. The results from SEM and X-ray diffraction (XRD) showed that as the EG content increases, graphite sheets increase, leading to a high probability of re-stacking and poor dispersion as well, however the synergy rendered an increase in the storage modulus for the composite containing low content of EG (5phr) in both the EG and clay containing samples. The addition of EG showed a slight increase in thermal stability,but the presence of C15A decreased the onset of degradation of EVA/PCL blend. However, at high temperatures the synergistic effect of EG and C15A showed better thermal stability for EVA/PCL blend than EG alone. The addition and increase in EG content improved thermal conductivity of the EVA/PCL blend in both the clay containing and EG containing samples, however the clay-containing samples showed lower values compared to EG only.

Highlights

Blending of more than two polymers to achieve distinct properties that separate materials do not possess is one of the most applicable techniques widely practiced
Synergistic Effect of expanded graphite (EG) and Cloisite 15A on the Thermomechanical Properties and Thermal Conductivity of ethylene–vinyl acetate copolymer (EVA)/PCL Blend flakes protruding like a scaled worm
The dynamic mechanical analysis showed an increase in the storage modulus for the composite containing low content of EG (5phr) in both the non-clay and clay containing samples

Summary

Introduction

Blending of more than two polymers to achieve distinct properties that separate materials do not possess is one of the most applicable techniques widely practiced. Most of the polymer blends are immiscible or incompatible on a molecular scale for thermodynamic reasons such as small combinatorial entropy and positive enthalpy of mixing. The effectiveness of immiscible blends is strongly influenced by phase morphology i.e. shape and size as well as the properties of each polymer component[1,2,3]. Polymer blending has the following advantages: cheap, processable, and distinct properties can be achieved depending on the composition and preparation methods[4,5]. Biodegradable polymers receive increased attention because of their biodegradability and thermoplastic properties. Ethylene–vinyl acetate copolymer (EVA) is a commodity plastic material resulting from the copolymerization of ethylene and vinyl acetate (VAc)

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