Phase Morphologies and Mechanical Properties of High-Impact Polystyrene (HIPS) and Polycarbonate Blends Compatibilized with Polystyrene and Polyacrylate Block Copolymer

摘要

Phase morphology and mechanical properties of blends of high-impact poly- styrene (HIPS) and polycarbonate (PC) blends compatibilized with a polystyrene (PS) and polyarylate (PAr) (PS-PAr) block copolymer were investigated. Over a broad range of composition from 50/50 through 30/70, HIPS/PC blends formed cocontinuous structures induced by the flow during the extrusion or injection-molding processes. These cocontinu- ous phases had heterogeneity between the parallel and perpendicular directions to the flow. The micromorphology in the parallel direction to the flow consisted of stringlike phases, which were highly elongated along the flow. Their longitudinal size was long enough to be longer than 180 j.l.m, while their lateral size was shorter than 5 j.l.m, whereas that in the perpendicular direction to the flow showed a cocontinuous phase with regular spacing due to interconnection or blanching among the stringlike phases. The PS-PAr block copolymer was found to successfully compatibilize the HIPS/PC blends. The lateral size of the string- like phases could be controlled both by the amount of the PS-P Ar block copolymer added and by the shear rate during the extrusion or injection-molding process without changing their longitudinal size. The HIPS/PC blend compatibilized with 3 wt % of the PS-PAr block copolymer under an average shear rate of 675 s 1 showed a stringlike phase whose lateral size was reduced almost equal to the rubber particle size in HIPS. The tensile modulus and yield stress of the HIPS/PC blends could be explained by the addition rule of each compo- nent, while the elongation at break was almost equal to that of PC. These mechanical , properties of the HIPS/PC blends can be explained by a parallel connection model inde- r pendent of the HIPS and PC phases. On the other hand, the toughness factor of the HIPS/PC blends strongly depended on the lateral size of the stringlike phases and the rubber particle size in the HIPS. It was found that the size of the string phases and the , rubber par4cle should be smaller than 1.0 IJIn to attain a reasonable energy absorbency by blendng HIPS and PC.