Nonisothermal Crystallization Kinetics of Poly(lactic acid) Formulations Comprising Talc With Poly(ethylene glycol)

The nonisothermal crystallization behavior of poly(lactic acid) (PLA) in the presence of talc with poly(ethylene glycol) (PEG) was performed by using differential scanning calorimetry (DSC) and polarized optical microscopy. It was evidenced that talc together with PEG had a synergistic effect on enhancing the crystallization rate of PLA, despite the fact that the two additives had an opposite effect on the size and density of the spherulites. The nonisothermal crystallization data were analyzed by using three different kinetics models, namely, the Avrami, Ozawa, and Mo models. It was found that the Avrami method and the Mo model could describe the experimental data of the nonisothermal crystallization fairly well for all the specimens, whereas the Ozawa analysis failed to provide an adequate description of the nonisothermal crystallization of the PLA formulations comprising talc with PEG. The difference in the values of the Avrami exponent between neat PLA and its mixtures with talc and PEG suggested that the nonisothermal crystallization of the mixtures corresponds to a three-dimensional growth with heterogeneous nucleation. The activation energy for nonisothermal crystallization of PLA formulations was evaluated based on the differential isoconversional method of Friedman. POLYM. ENG. SCI., 50:2298-2305, 2010. (C) 2010 Society of Plastics Engineers