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ABSTRACT:The toughness of high-impact polystyrene based on ␥-radiation-vulcanized natural rubber (NR) was effectively enhanced by the addition of a block copolymer at the NR/polystyrene interface. An NR/polychloroprene (CR) composite latex particle was produced by the heterocoagulation technique for its use as a model in a compatibilization study. A nonionic surfactant (Tween 80), whose molecule bore poly(ethylene oxide) (PEO), was adsorbed onto the CR particle and allowed to form a complex between PEO and an indigenous surfactant (protein-lipid) on the NR particle surface. The presence of CR-Tween on the outer layer of the obtained composite polymer particle was characterized by the particle size, potential, and glass-transition temperature. That the film cast from the heterocoagulated latex showed better oil resistance than the NR film confirmed the NR/CR core-shell structure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 9 -13, 2003

Polyisoprene-block-polystyrene-block-polyisoprene (ISI) was synthesized by the iniferter route and its use, as compared to a commercial polystyrene-blockpolyisoprene-block-polystyrene (SIS), in the enhancement of the toughness of highimpact polystyrene (HIPS), prepared by the ␥-radiation vulcanized natural rubber (RVNR) latex/phase transfer/bulk polymerization technique, was investigated. Addition of 5% SIS was adequate as an interfacial agent, which effectively increased the unnotched Izod impact energy of HIPS, whereas use of 10% of ISI was required. A long polyisoprene block with two polystyrene segments of SIS was favorable for compatibilization of HIPS. Transmission electron micrographs revealed the uniform distribution of the block copolymer at the shell region of the rubber particle.

γ‐Radiation vulcanized natural rubber (RVNR)/phase transfer/suspension polymerization technique was used to prepare high‐impact polystyrene (HIPS) in bead form. The high notched Izod impact resistance of HIPS based on RVNR was observed and compared with that of unmodified PS. The impact resistance of HIPS based on RVNR was further enhanced by addition of 10% of polystyrene‐block‐polyisoprene‐block‐polystyrene copolymer. A mesh structure of all crosslinked rubber particles containing polystyrene and long crazes in HIPS were observed under electron microscopy. Copyright © 2003 Society of Chemical Industry