Crystallization morphology and crystallization kinetics of poly(lactic acid): effect of N-Aminophthalimide as nucleating agent

The effect of N-Aminophthalimide compound (NA-S) as nucleating agent on crystallization behavior and morphology of poly(lactic acid) was studied. With polarized optical microscope (POM), the unique phenomena of nucleation and epitaxial crystallization of PLA/NA-S system were observed. Dynamic morphology of crystallization was also studied by POM to investigate the relationship between growth behavior of PLA and nucleating agent. Isothermal and non-isothermal crystallization behavior of PLA were studied by differential scan calorimeter (DSC). When nucleating agent was added, a new peak appeared in wide angle X-ray diffraction (WAXD) compared with pure PLA, indicating the nucleating effect of NA-S on crystallization of PLA. All the results indicate that the nucleating agent of NA-S shows obvious nucleating effect on isothermal crystallization above 120 A degrees C and in non-isothermal crystallization after it is added in PLA, that is, the induction crystallization time is reduced, the crystallization rate and nucleation density of PLA are increased.