DEGRADATION MECHANISM OF POLY(PROPYLENE CARBONATE) POLYOLS

Degradation of poly(propylene carbonate) polyols (PPC) was studied. It was revealed that the degradation consists of unzipping depolymerization and random chain breaking. The unzipping depolymerization results in a cyclic byproduct, propylene carbonate, and tends to occur in the presence of the residual polymerization catalyst, if not deactivated. It may be accelerated by raising the temperature or being exposed to light. The random chain breaking is seen as molecular weight decrease, CO_2 release, and unsaturated end group formation. The PPC resin was found to keep stable when stored under dark and cool conditions.