PREPARATION AND PROPERTIES OF SAN EPDM/CPE TERNARY BLENDS/

Melt blends of poly(styrene-co-acrylonitrile) (SAN) with ethylene-prop ylene-diene (EPDM) terpolymer and/or chlorinated polyethylene (CPE) ha ve been prepared in a twin-screw compounding machine. The morphologica l textures of the blends were determined from scanning electron micros copy; mechanical and rheological properties were measured using an Ins tron, Rheometrics dynamics spectrometer (RDS) and Rheometrics mechanic al spectrometer (RMS). Scanning electron microscopy revealed that the blend is heterogenous. The use of an EDPM alone failed to give any sig nificant increase in the toughness of brittle SAN. However, a combinat ion of the two rubber (EDPM and CPE) modifiers produced a synergistic toughening mechanism. Tensile strength and flexural strength decrease almost linearly with increasing amount of EDPM and/or CPE, but elongat ion at break increases. (C) 1998 Elsevier Science Ltd. All rights rese rved.