Polystyrene/Phosphonium Organoclay Nanocomposites by Melt Compounding

Abstract

Abstract Polystyrene-montmorillonite nanocomposites were prepared by melt compounding, using several ammonium and phosphonium organoclays. Melt processing was carried out in a twin screw extrusion system, specially modified to produce improved dispersion and longer residence time. The effect of molecular weight of polystyrene on clay dispersion and property enhancement was evaluated. Nanocomposite structure was characterized by wide angle x-ray diffraction (WAXD) and transmission electron microscopy (TEM). Thermal stability and mechanical and barrier properties were also determined. The quality of dispersion of organically modified montmorillonite depended on the molecular weight of the polystyrene resin. Barrier properties were measured and compared to predictions of permeability models available in the literature. Clay dispersion and property enhancement were explained in relation to the surface characteristics of the organoclays, and the work of adhesion at the polystyrene-clay interface was correlated with the tensile modulus of the nanocomposites.