Toughening of SAN Copolymers by an SAN Emulsion Grafted Rubber

摘要

A series of styrene/acrylonitrile (SAN) copolymers have been blended with an SANgrafted butadiene rubber to form ABS type materials. The major focus has been the effects of composition of the SAN matrix copolymer, for a fixed SAN graft, on blend toughness, deformation behaviour and morphology. The AN content varied from 0 to 40% in the matrix copolymers, while the AN content of the emulsion-made graft was fixed at 22.5%. Maximum strength and toughness were observed for compositions based on SAN matrices containing 34% AN. Mechanical dilatometry revealed no major changes in deformation mechanism as the AN content of the matrix changed. Most of the deformation was due to dilatational processes, presumably crazing. Transmission electron photomicrographs, on the other hand, showed differences in rubber particle dispersion. The morphology revealed by scanning electron microscopy of fracture surfaces distinguished the ductile and less ductile blends. Issues relating to the miscibility of the component polymers and adhesion are discussed. (JES)