The study of various styrene-butadiene copolymers as compatibilisers in bulk blends of polystyrene/polybutadiene

blends, produced by compositional quenching, were used to examine the effectiveness of different styrene-butadiene copolymers as interfacial agents in blends of polystyrene (PS) with polybutadiene (PB). Each polymer blend was compression molded for various times to allow particle ripening and was then tested for impact strength. The most effective compatibiliser proved to be a long, asymmetric diblock, which could entangle in both homopolymer phases. Diblocks with short PS segments were inadequate as interfacial agents, presumably because their short PS blocks were easily pulled from the matrix. Random copolymers with a composition near 50/50 were successful as interfacial agents, but the impact strength declined with a decrease in PS composition of the copolymer. A commercial multiblock copolymer, Phillips K-Resin(R), also proved to be reasonably effective compatibiliser, giving better impact strength than the HIPS control. (C) 1998 Elsevier Science Ltd. All rights reserved.