The inherent weak crystallization capacity has an impact on the processability and serviceability of poly(lactic acid) (PLA) and limits its application. D-mannitol (DM) and xylitol (Xy), acting as a nucleation accelerant, were melt-blended with poly(L-lactic acid) (PLLA) and the nonisothermal crystallization behavior was investigated. At 1% dosage, the crystallization temperatures of polyol-modified PLLAs are 10–15°C higher than those of neat PLLA in the cooling rate range of 5–20°C. The theoretical half-time of crystallization (t_1/2) of the Jeziorny model remains constant over the cooling rate range of 10–20°C min⁻¹, in contrast to the greatly reduced t_1/2 reported for heterogeneous nucleating agents. Xy is more effective than DM in promoting crystallization. It increases the crystallinity of PLLA to ~40% within the 1%–5% dosage; and the activation energy of nonisothermal crystallization calculated by the Friendman method follows the order of magnitude: neat PLLA ˃ PLLA/DM ˃ PLLA/Xy. Polyols promote the crystallization of PLLA by a mechanism different from heterogeneous nucleation, providing an efficient and biosafety approach to improve the performance of PLA.

中文翻译：

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多元醇促进聚（L-乳酸）的非等温结晶

固有的弱结晶能力影响了聚乳酸（PLA）的加工性和使用性并限制了其应用。将作为成核促进剂的D-甘露醇 (DM) 和木糖醇 (Xy) 与聚 (L-乳酸) (PLLA) 熔融共混，并研究了非等温结晶行为。在 1% 的用量下，多元醇改性 PLLA 的结晶温度在 5-20°C 的冷却速率范围内比纯 PLLA 的结晶温度高 10-15°C。Jeziorny 模型的理论结晶半衰期 ( t _{1/2 ) 在 10–20°C min} ⁻¹的冷却速率范围内保持恒定，这与大大降低的t _{1/2形成对比}报道了异质成核剂。Xy 在促进结晶方面比 DM 更有效。在1%~5%的用量范围内，将PLLA的结晶度提高到~40%；Friendman 法计算的非等温结晶活化能遵循数量级：neat PLLA ˃ PLLA/DM ˃ PLLA/Xy。多元醇通过不同于异相成核的机制促进 PLLA 的结晶，提供了一种有效且生物安全的方法来提高 PLA 的性能。