Effect of miscibility on barrier and mechanical properties of PS/poly(ethylene-co-acrylic acid) composite latex

The effects of miscibility enhancement between polystyrene (PS) and poly(ethylene-co-acrylic acid) (EAA) on dynamic mechanical properties, barrier property, and tensile strength were investigated. Ethylene-modified latexes were prepared by the emulsion polymerization of styrene using EAA, [Mn: 18 800; acid number: 140], as a polymeric emulsifier. The EAA-grafted-PS in-situ-formed during the emulsion polymerization lead to the improvement of miscibility between PS and EAA. The dynamic mechanical properties of the ethylene-modified PS films exhibited a single glass transition temperature (Tg) value, thus conforming to the law of miscibility. The grafted and anchoring EAA molecules onto PS particles resulted in significant increase of chemical resistance. Additionally, the tensile strength property was improved for the ethylene-modified PS system due to the enhanced compatibility between PS and EAA, compared with simple blends.