Effect of modification of montmorillonite on the cellular structure and mechanical properties of ethylene vinyl acetate/clay nanocomposite foams

Abstract

Nanocomposite foams, based on ethylene vinyl acetate copolymer, were prepared by melt blending of ethylene vinyl acetate with organically modified montmorillonite and at a high curing pressure of the blends. The organically modified montmorillonites were obtained by the modification of montmorillonite with octadecyl trimethyl ammonium chloride, dimethyl octadecyl hydroxy ethyl ammonium nitrate and dioctadecyl dimethyl ammonium chloride as the intercalating agent. The intercalation effect of montmorillonite layers by the tetraalkylammonium cations was characterized by X-ray diffraction. The state of organically modified montmorillonite in the blends was studied using transmission electron microscopy and the cellular microstructure of the foamed samples was observed by scanning electron microscope. The effects of tetraalkylammonium modification of montmorillonite on the cellular structure and the mechanical properties of the ethylene vinyl acetate-based foams were investigated. It was found that organically modified montmorillonites with different alkyl chains played important role in the formation of the microstructure and the mechanical properties of the ethylene vinyl acetate/organically modified montmorillonite nanocomposite foams. With the alkyl chains, it was possible to obtain ethylene vinyl acetate nanocomposite foams with significantly lowered density and improved mechanical properties.