BLENDS OF POLY(VINYL CHLORIDE) WITH ACRYLONITRILE-CHLORINATED POLYETHYLENE-STYRENE COPOLYMER .1. MISCIBILITY, PHASE-BEHAVIOR, AND THERMAL-PROPERTIES

Blends of poly(vinyl chloride) (PVC) and acrylonitrile-chlorinated pol yethylene-styrene (ACS) copolymer were prepared by melt blending. Misc ibility, phase behavior, and thermal stability were studied using diff erential scanning calorimetry (DSC), scanning electron microscopy (SEM ), and thermogravimetric analysis (TGA). The DSC study showed that the blends have three glass transition temperatures (T-g). The blends exh ibit a three-phase structure; a chlorinated polyethylene (CPE) rubbery phase was found to be dispersed in a continuous matrix consisting of both PVC-rich and SAN-rich phases. The interfaces between any two of t he three phases are well bonded. PVC is immiscible with CPE in ACS but partially miscible with poly(styrene-co-acrylonitrile) (SAN with 25% AN content) in ACS. From the T-g data, the SAN appears to dissolve mor e in the PVC-rich phase than does the PVC in the SAN-rich phase. The a pparent polymer-polymer interaction parameter [(chi(12))(app)] for the pair PVC/SAN was calculated to be 0.0055 at 170 degrees C. TGA analys is revealed that there exists interaction during the degradation of th e two polymers in the blends.