MISCIBILITY IN BLENDS OF STEREOREGULAR POLY(METHYL METHACRYLATE)S WITH CHLORINATED POLYETHYLENES AND CHLORINATED POLY(VINYL CHLORIDE)S

Critical miscibility Phenomena in binary blends of atactic, isotactic, or syndiotactic poly(methyl methacrylate)s (a-, i-, and s-PMMA) with chlorinated polyethylene (CPE) or chlorinated poly(vinyl chloride) (CPVC), each with systematically varying degrees of chlorination, were studied by measuring the glass transitions by differential scanning calorimetry. These systems show lower critical solution temperatures (LCSTs). The reversibilities of phase separation above the LCST and homogenization below the LCST in the systems were confirmed. The respective miscibility diagrams, i.e., miscibility as a function of temperature and composition expressed in chlorine weight percent, typically display ''miscibility windows.'' Both CPE and CPVC are more miscible with s- and a-PMMA than with i-PMMA. The miscibility behavior of the PMMA/CPE system differs from that of the PMMA/CPVC system reflecting the influence of the microstructures of CPE and CPVC.