Non-isothermal crystallization kinetics of sucrose palmitate reinforced poly(lactic acid) bionanocomposites

Poly(lactic acid) (PLA) bionanocomposites containing sucrose palmitate (SP), which is a non-toxic food additive, were prepared by a simple solution-casting approach. In the current work, the investigation of non-isothermal cold crystallization kinetics of PLA and PLA-SP bionanocomposites was performed using a differential scanning calorimeter under the dynamic heating regime of 2.5, 5, 7.5 and 10 degrees C/min. Avrami model was employed to study the effect of SP on cold crystallization kinetics of PLA. For PLA-SP bionanocomposites, Avrami coefficients obtained in the range of similar to 2.5-4 and decreasing trend of the t(1/2) values indicated the faster crystallization mechanism in comparison to neat PLA. The nucleation and growth mechanism involved in the non-isothermal crystallization of PLA and PLA-SP bionanocomposites were further analyzed by Tobin model. Kissinger method has been employed to determine the crystallization activation energy (Delta E) for neat PLA and PLA-SP bionanocomposite. The nucleation as well as the growth of spherulites in neat PLA and PLA-SP bionanocomposites was observed using polarized optical microscopy. After incorporation of SP in the PLA matrix, an increase in the overall crystallization rate for PLA was reflected by the decline in the nucleation induction period and subsequent enhancement in the primary nucleation sites.