Properties of polystyrene modified with a thermoplastic elastomer
Polimery 1994, No 7-8, 453
The mechanical and thermal properties as well as microstructure of polystyrene prepared by radical polymerization of styrene in bulk in the presence of 10% Wod:-copoly(styrene/butadiene/styrene) (SBS) or 10% epoxidized block-copoly(styrene/epoxybutadiene/styrene) [E(SBS)] were compared. In the thus-prepared systems of PS/SBS or PS/E(SBS) the content of crosslinked copolymer was 17 or 19%, respectively. Block copolymers were also present in the non-crosslinked (soluble in toluene) fraction. There is a good correlation between impact strength (reinforcement effect) and physical structure of the investigated systems as determined by the method of transmission electron microscopy (ТЕМ). In the system of PS/SBS, particles of the disperse phase with diameters in the range of 0.05—0.2 pm are spherical or oval and have a shell rich in SBS copolymer (acore-and-shell structure). In the system of PS/E(SBS), particles of the disperse phase have the shape of irregular rods with length in the range of 0.05— 0.3 pm and a thickness of 0.05 pm and do not contain sub inclusions of polystyrene. Differences in the physical structure of these systems are due to differences in mutual compatibility of PS with block copolymers of SBS type and with those of E(SBS) type. PS modified with the epoxidized block copolymer E(SBS) (a new polymer system) exhibits much better adhesive properties (twice as high adhesion to steel) than PS modified with the block copolymer SBS.
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