Promoting Effect of Synergetic Nucleating Agent on Crystallization Behavior of Polylactic Acid

ABSTRACT Modulating the crystallization behavior of polylactic acid (PLA) is significant for expanding its application range. In this article, a synergetic nucleating agent of talc and D ‐sorbitol combination is incorporated into PLA via melt blending to enhance the crystallization of PLA. Then, differential scanning calorimetry (DSC) is employed to study the nonisothermal and isothermal crystallization behaviors, and the analysis of isothermal crystallization kinetics is carried out according to the Avrami equation, which has confirmed that the synergetic nucleating agent can promote the increase of the crystallinity from 3.5% to 43.8% and enhance the crystallization rate. Meanwhile, the analysis of Lauritzen–Hoffman's secondary nucleation theory reveals an obvious decline in the nucleation constant and fold surface free energy of PLA chains, which means a superior nucleating efficiency. Furthermore, the results of polarized optical microscopy (POM) demonstrated that the addition of the synergetic nucleating agent resulted in a greater number of spherical crystals with smaller sizes simultaneously visible in the field of view, indicating the synergetic nucleating agent promotion effect on PLA crystallization.