聚乳酸/聚（3-羟基丁酸酯-co-4-羟基丁酸酯）/改性高岭土纳米复合材料的结晶、动态力学及流变行为

摘要

In order to improve the synthetical properties of polylactide (PLA)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)), PLA/P(3HB-co-4HB)/modified kaolin nanocomposites were prepared by melt blending method. The crystallization, dynamic mechanical properties, rheological behaviors and surface structure of the composites were studied respectively with differential scanning calorimeter (DSC), dynamic mechanical analysis (DMA), rotary rheometer and scanning electron microscope (SEM). The results indicate that the cold crystallization temperature of the composites decreases gradually, which reduces by 12.5℃, and the crystallization capacity is improved. In addition, crystallinity increases from 21.65% to 35.22% with an increase of 62.68%. DMA shows that the energy storage modulus E′ and glass transition temperature of the composites increase firstly and then decrease as the modified kaolin content is increased. At melting state, viscosity decreases when the sheer rate is increased, which shows that the composites are pseudoplastic fluid. When the addition of modified kaolin achieves 4%, the notched impact strength of the composites improves significantly. SEM observations show that a small amount of modified kaolin can disperse uniformly in PLA/P(3HB-co-4HB), and it can remarkably improve the toughness of the composites.%　　为提高聚乳酸(PLA)/聚(3-羟基丁酸酯-co-4-羟基丁酸酯)(P(3HB-co-4HB))基体的综合性能，采用熔融共混法制备聚乳酸/聚(3-羟基丁酸酯-co-4-羟基丁酸酯)/改性高岭土(modified kaolin)纳米复合材料。利用DSC、DMA、旋转流变仪、扫描电镜(SEM)等对复合体系的结晶、动态力学性能、流变行为、表面结构等进行了研究。结果表明：复合体系的冷结晶温度逐渐变小，降低了12.5℃，结晶能力有所提高。此外，结晶度由21.65%增加到35.22%，提高了62.68%。DMA结果显示，随着改性高岭土添加量的增多，复合体系的储能模量E′和玻璃化转变温度出现先增大后减小的变化。熔融态下，复合体系的黏度随剪切速率的增大而减小，属假塑性流体。当体系中改性高岭土添加量为4%时，材料的缺口冲击强度有明显的改善。利用 SEM 发现，少量改性高岭土可以均匀地分散在 PLA/P(3HB-co-4HB)基体中并能显著提高复合体系的韧性。