Polypropylene/Polystyrene Blends Prepared By Diffusion And Subsequent Polymerization In Polypropylene Pellets After Injection Molding

PP/PS quasi-nanoblend pellets were synthesized by diffusion and subsequent polymerization of styrene in iPP pellets via a two-step procedure and then processed by injection molding. The PS distributions along the thickness direction of the molded bars were investigated by Micro-FTIR, showing almost homogeneous distribution no matter whether the PS distribution in the blend pellets is homogeneous. The morphology of the molded bars was investigated by FESEM, revealing two types of particles (small spherical and bigger irregular-shaped complex aggregates) and good interfacial adhesion between particles and matrix. The particles are mainly in nano and submicron sizes, and only few particles approach 1 mu m. The mechanical properties of the molded bars were evaluated by uniaxial tensile testing, showing a significant reinforcing effect without significantly loosing ductility. The yield strength of all the blends increase 20-27% compared to neat PP and the elongations at break are all over 300%. The remarkable mechanical properties of the molded bars were correlated with their morphology. (C) 2016 Wiley Periodicals, Inc.