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) (CP VC), each with systematically varying degrees of chlorination, were st udied by measuring the glass transitions by differential scanning calo rimetry. These systems show lower critical solution temperatures (LCST s). The reversibilities of phase separation above the LCST and homogen ization below the LCST in the systems were confirmed. The respective m iscibility diagrams, i.e., miscibility as a function of temperature an d composition expressed in chlorine weight percent, typically display ''miscibility windows.'' Both CPE and CPVC are more miscible with s- a nd a-PMMA than with i-PMMA. The miscibility behavior of the PMMA/CPE s ystem differs from that of the PMMA/CPVC system reflecting the influen ce of the microstructures of CPE and CPVC.