Effect of organo-smectite clays on the mechanical properties and thermal stability of EVA nanocomposites

Abstract

Ethylene vinyl acetate (EVA) nanocomposites containing hydrophobic organo-clays were prepared by a solution blending method to investigate the role of organic modifiers stabilized in the interlayer space of host clays on the thermal stability and mechanical strength of EVA. The smectite clays such as Mt. (Na-montmorillonite), Mica (Na‑fluorine mica), and Ht (Na-hectorite) were used as the host with different particle sizes, but hydrophobically modified by intercalating the long chained alkylammonium surfactants like cetyltrimethylammonium (CTA) bromide, and dimethyldistearylammonium (DMDSA) bromide to form organo-clays. Thus, prepared organo-clays were dispersed homogeneously in a toluene solution of EVA, and then the toluene was evaporated to obtain the organo-clay/EVA nanocomposites. According to the powder XRD analyses for all the nanocomposites, the CTA-clays were better exfoliated and dispersed in EVA matrix than the DMDSA-ones. Among three CTA-clay/EVA nanocomposites, the CTA-Mica/EVA one was determined to be the best in terms of thermal stability compared to the other two nanocomposites, CTA-Mt/EVA and CTA-Ht/EVA. The thermal stability of the CTA-Mica/EVA nanocomposite was significantly improved by ~38 °C, compared to that of the pristine EVA. Upon increasing the CTA-Mica loading concentration up to 12 wt% in EVA matrix, the Young's modulus and tensile strength of the EVA nanocomposites were increased up to 54% in maximum. It is, therefore, suggested that the CTA-Mica is a potential nanofiller for enhancing the thermal stability and mechanical properties of EVA.