EFFECT OF ZINC-CHLORIDE ON THERMAL-DECOMPOSITION OF POLYMETHACRYLIC AND POLYACRYLIC ESTERS

Zinc chloride reduces the rate of thermal and thermooxidative decompositions of polymethacrylic esters and increases the thermal decomposition rate of polyacrylic esters. Mechanisms of the thermal decompositions of polymethacrylates and polyacrylates in the presence of ZnCl2 have been suggested. For thermal decomposition polymethacrylic esters, the rate of depolymerization decreases due to the formation of cycles in a polymer chain by reaction of Zinc chloride with neighbouring ester groups. For thermooxidative decomposition of polymethacrylates, ZnCl2 decreases also the rate of initiation of depolymerization and causes decomposition of hydroperoxide groups by a heterolytic mechanism. The increase in thermal decomposition rate of polyacrylic esters results from the high activity of complexes of ester groups and ZnCl2 in decomposition reactions with formation of alcohol and CO2 through Cameron mechanism. © 1979.