Nonisothermal crystallization behavior and kinetics of poly( L-lactide-co-propylene carbonate)

Poly(L-lactide-co-propylene carbonate) was synthesized via the terpolymerization of L-lactide, CO2 and propylene oxide using zinc carboxylates as catalyst. The nonisothermal crystallization behavior and kinetics of the samples with and without catalyst residual were investigated using differential scanning calorimetry. Both the peak of melt crystallization temperature (T-p) and the enthalpy of the cold crystallization process (Delta H) decrease with increasing PC content. Avrami-Jeziorny model, Owaza model and Mo model were used to describe the crystallization process. Avrami-Jeziorny analysis presents the crystallization kinetics, while neither the Ozawa nor the Mo model could successfully describe them. Kissinger's method was finally employed to calculate the activation energy for the transport of the macromolecular segments to the growing crystal surface. The results show that the existence of catalyst within polymer sample and increased PC content lead to an increase of energy barrier.