Morphology, thermal behavior, rheological, and mechanical properties of polypropylene/polystyrene blends based on elongation flow

Binary blends comprised of polypropylene (PP) and polystyrene (PS) were prepared by a novel eccentric rotor extruder based on elongation flow. The morphology, thermal behavior, rheological and mechanical properties were investigated. As the enhanced mixed dispersion based on the novel extruder, the dispersed PS phase were uniformly dispersed in the PP matrix when the PS not more than 40%, and a distinct cocontinuous phase structure emerged when the PS content was 50%. The size of the dispersed PS phase related to the PS content and the processing flow filed influenced the crystallization behavior and the thermal stability of the blends. The PS droplet with small size could act as a nucleating agent for PP to improve the crystallinity, and PS droplet with large size could promote the thermal and heat transfer between the PS droplets and PP matrix which decreased the thermal stability. The rheological results showed that the compounding with PS into the PP matrix increased the storage and loss modulus as well as the complex viscosity of the materials. When the PS content not more than 20%, the blends showed good impact resistance, and PP/PS blends 30% PS showed good tensile and flexural properties. This study gives a new perspective for the structure and properties of the binary PP/PS blends prepared based on elongation flow.