Novel methods for synthesis of high-impact polystyrene with bimodal distribution of rubber particle size

By using in situ prepolymerization and radiation curing, high-impact polystyrene (HIPS) with a bimodal distribution of the size of the rubber particles (bimodal HIPS) was synthesized in the presence of ultrafine full-vulcanized powdered styrene-butadiene rubber (UFPSBR) and polybutadiene rubber (BR). TEM photographs indicated that UFPSBR was dispersed uniformly as a single particle with a diameter of about 100 nm. On the other hand, bimodal HIPS with different rubber particle size distributions could also be obtained by blending HIPS and UFPSBR grafting styrene (UFPSBR-g-St) with different grafting yields. The bimodal HIPS with the smallest rubber particle size, at about 100 nm, could be prepared by blending the monomodal HIPS containing big rubber particles with polystyrene/UFPSBR. (c) 2008 Wiley Periodicals, Inc.