The Preparation of Crystalline and Heat Resistance PLA in the Presence of Fully Biodegradable Macromolecular Nucleating Agent

In this study, branched poly(lactic acid) (PLA) was synthesized through melt blending, which was blended with linear PLA (L-PLA) to enhance the crystallization. Nonisothermal and isothermal crystallization studies demonstrated that nucleated PLA exhibited a crystallization temperature and melt crystallinity of 119.0 °C and 48.0%, respectively, at the highest degree of entanglement of branched PLA (B-PLA). Following a simple annealing treatment, the Vicat softening temperature (VST) and heat deflection temperature (HDT) of nucleated PLA reached 157.2 and 94.3 °C, respectively. The presence of dipole interactions among molecular chain segments during the initial stages of nucleation was revealed via in situ infrared spectroscopy, which facilitated the adsorption of L-PLA onto B-PLA, thereby allowing branched segments to serve as nucleation sites for L-PLA. This comprehensive analysis elucidated the influence of B-PLA on the crystallization behavior of L-PLA and established a correlation between its degree of entanglement and nucleation efficacy. It could be concluded that nucleated PLA retains its biodegradability while demonstrating improved crystallization and heat resistance.