聚乳酸增韧改性与结晶性能调控及其机理

Polylactide (PLA) is one of the most important bio-based aliphatic polyesters, and possesses excellent biodegradability and biocompatibility as well as good rigidity and thermoplastic process ability. It has potential application in fields like medical devices, textile, and food packaging, etc. However, the poor impact resistance and slow crystallization rate of PLA limit its extensive applications. Therefore, in present study, the impact toughness and crystallization behavior of PLA are planned to be tailored simultaneously by the addition of poly (propylene carbonate) (PPC) and low molecular weight hydrazide compounds, so as to obtain fully biodegradable ternary blends with balanced properties. Systematic investigation would be performed on the variation of multi-phase structure, crystallization behavior and physical-mechanical properties with the blends composition and processing conditions. The correlation between the multi-phase behavior and crystallization regulation would be explored as well. In addition, the essence of interaction among different components would be well elucidated, and thus modification mechanisms for the impact toughness and crystallization behavior of PLA would be suggested. Finally, the structure-property relationship of this system would be established. It is expected that the present study could contribute to the research and development of related high-performance biodegradable polymer materials.

聚乳酸（PLA）是一种重要的生物基脂肪族聚酯，兼具生物降解性和生物相容性，同时具有较高的刚性和良好的热塑加工性，在医药卫生、纺织服装和食品包装等领域存在广泛应用价值。但是由于韧性差、结晶速率慢，一定程度上限制了其应用。本课题拟通过添加聚碳酸亚丙酯和酰肼类有机小分子成核剂，实现对PLA冲击韧性和结晶性能的同步有效调控，制备出综合性能优异的PLA基生物降解复合材料。将系统研究共混物相态结构、结晶行为和物理机械性能随共混物组成和加工工艺条件的变化，探索共混物多相相行为与结晶调控行为之间的相互影响，揭示共混体系内各组分间的相互作用本质，进而提出增韧改性和结晶调控机理，最终建立共混体系宏观性能与微观结构和制备条件之间的关系。本研究可为生物降解高分子材料的开发和高性能化提供理论依据和技术指导。

聚乳酸（PLA）是一种重要的生物基脂肪族聚酯，具有良好的生物降解性和生物相容性，在生物医药等领域具有广阔的应用前景。本课题以PLA为研究对象，以改善其结晶速率和冲击韧性为目的，通过添加酰肼类有机小分子（TMBH）和聚碳酸亚丙酯（PPC）对其进行结晶调控和增韧改性，系统研究了PLA共混物的结构与性能。结果表明：TMBH可以有效提高PLA的结晶能力，其成核效率与其在PLA基体中的溶解分散状态相关，受添加量和熔融退火温度的影响。原位变温红外光谱表明TMBH的成核效应源自于其与PLA分子间极性基团的相互作用，该作用加速了PLA分子间的骨架构象有序和分子内103螺旋结构的形成。PPC可以有效提高PLA的断裂伸长率，其增韧效果随含量的增加而逐渐增大；当PPC含量达到40 wt%时，PLA和PPC呈现两相双连续结构，受到外力作用时，PPC相作为应力集中点诱发PLA基体的塑性形变和剪切屈服，从而形成大量剪切带吸收能量发生脆韧转变。最后，通过对PLA/PPC/TMBH三元共混体系的研究，建立共混物宏观力学性能与其微观结构和组分配比的关系。研究结果可为PLA的共混改性和加工应用提供可靠依据，为聚合物的结构调控及其与性能的关系提供高效的研究方法。