Abstract The drawback of the application for poly( l -lactide) (PLLA) is the low crystalline rate and crystallinity obtaining via normal processing methods. Modifying crystallization of PLLA has been found to be an efficient way to improve its mechanical and heat resistance properties. In this wok, 4, 4′-diphenylmethane diisocyanate (M) and benzohydrazine (P) were employed into PLLA melt to in-situ form nucleating agents. The in-situ melting reaction was confirmed by a nuclear magnetic resonance spectroscopy. The crystallization behavior and crystalline morphology were investigated by a differential scanning calorimetry, a polarized optical microscopy and a field emission scanning electron microscope. The crystalline rate of PLLA was abruptly enhanced by adding (M+P) and melting reaction with PLLA. The crystallization half-time of PLLA dramatically decreased from 42.0 to 1.1 min at 130 °C by the in-situ formation of nucleating agents. The crystallinity of PLLA increased from 10.3 to 42.1 by adding 0.25% (M+P) and melting reaction for 8 min. Furthermore, the size of PLLA crystals was dramatically reduced because of the nucleating effect. Accompanied with improvement on crystallinity, the Vicat softening temperature of PLLA shifted from 57.4 °C to 93.7 °C by the in-situ reaction with 6.00% (M+P), and indicating heat resistance enhancement.

中文翻译：

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通过与二异氰酸酯和苯甲肼原位熔融反应形成成核剂，在聚（L-丙交酯）中实现高结晶速率和结晶度

摘要 聚(l-丙交酯) (PLLA) 应用的缺点是通过常规加工方法获得的结晶速率和结晶度低。已发现改变 PLLA 的结晶是改善其机械和耐热性能的有效方法。在该锅中，将 4, 4'-二苯基甲烷二异氰酸酯 (M) 和苯并肼 (P) 用于 PLLA 熔体中以原位形成成核剂。核磁共振光谱证实了原位熔融反应。通过差示扫描量热法、偏振光学显微镜和场发射扫描电子显微镜研究结晶行为和结晶形态。通过添加(M+P)和与PLLA的熔融反应，PLLA的结晶速率突然提高。由于成核剂的原位形成，PLLA 的结晶半衰期在 130°C 时从 42.0 分钟显着降低到 1.1 分钟。通过添加0.25% (M+P) 和熔融反应8 分钟，PLLA 的结晶度从10.3 增加到42.1。此外，由于成核效应，PLLA 晶体的尺寸显着减小。随着结晶度的提高，PLLA 的维卡软化温度从 57.4 °C 转变为 93.7 °C，与 6.00% (M+P) 进行原位反应，表明耐热性增强。