多相聚酯/核壳粒子共混体系双向协同增韧研究

The brittle-ductile transition takes place early for the core-shell particles toughening poly(butylene terephthalate) (PBT) blends with the addition of polycarbonate (PC). The toughness of PC/core-shell particles blends can be improved with the introduction of PBT. According to the phemomenon as mentioned above, the point of synergistic toughening mechanisms in double way was put forward. The toughener used in the project was reactive MBS-g-GMA core-shell particles and the synergistic toughening mechanisms were investigated. The degree of interchange esterification between PBT and PC, the change of PBT crystallization behavior, the relation between the physical ageing of PC and synergistic toughening was studied in detail. Vu-Khanh equation, Eyring equation and Ludwik-Davidenkov-Orowan btittle-ductile transition theory were used to associate the synergistic toughening mechanisms with the fracture behavior of the polyester blends. In the present study, the third component was introduced into the multi-phase polymer blends to modidy the chain structure of the matrix, state of aggregation, physical ageing. So the fracture characters of the blends was changed and the synergistic toughening was achieved for the polymers with crystallization and physical ageing properties. The reseach is beneficial to inrich the toughening theory of polymers and induct the exploitation of polyer alloys with higher toughness.

针对聚碳酸酯（PC）促进核壳粒子增韧聚对苯二甲酸丁二酯（PBT）共混体系脆韧转变提前发生和PBT促进核壳粒子增韧PC体系冲击韧性显著提高的现象，提出多相聚酯/核壳粒子共混体系双向协同增韧的观点。课题所用增韧剂为反应性核壳粒子MBS-g-GMA，探讨协同增韧机理。研究PBT与PC之间的酯交换反应程度、PBT结晶行为变化、PC物理老化行为改变与协同增韧的关系。利用Vu-Khanh方程、Eyring方程、Ludwik-Davidenkov-Orowan脆韧转变理论将多相共混体系协同增韧与共混物断裂行为变化相关联。在协同增韧作用下，通过设计MBS-g-GMA内部结构控制其空洞化能力制备出更高韧性的合金材料。本课题通过第三组分聚合物引入改变基体链结构、聚集态结构、物理老化等特性，从而改变增韧塑料断裂行为，实现对结晶性、物理老化特性塑料协同增韧，丰富高分子增韧理论，指导高韧工程塑料合金开发有重要意义

采用乳液聚合方法制备了MBS-g-GMA反应性核壳粒子用于PBT/PC共混物的增韧改性。主要研究了PBT、PC之间的酯交换反应程度、酯交换的抑制、酯交换促进剂与抑制剂对MBS-g-GMA增韧PBT/PC性能的影响；考察了PC对PBT结晶行为的改变；研究了PC物理老化行为与PBT协同增韧的关系；利用Vu-Khanh方程、Eyring方程、Ludwik-Davidenkov-Orowan脆韧转变理论分析了多相聚酯共混体系的断裂行为；研究了核壳粒子微观结构调控对共混物性能的影响。通过研究发现加工温度和PBT与PC的组成对二者的酯交换影响显著，共混物中磷酸类化合物的引入可以降低PBT/PC的酯交换程度。抑制酯交换不利于MBS-g-GMA对PBT/PC的增韧。酯交换促进剂的加入提高了MBS-g-GMA对PBT/PC的增韧能力。PC的加入降低了PBT的结晶速度和结晶能力，对晶型没有改变。PBT影响PC的物理老化能力，减弱了物理老化对PC断裂行为的影响。PC的主要贡献是在共混物受到冲击外力作用时，首先发生屈服形变。而界面层的PC由于与PBT之间的交换反应导致二者之间有较好的界面结合强度，因此促进PBT基体剪切屈服的提前发生，起到协同增韧作用。通过调控MBS-g-GMA核壳粒子的微观结构可以改变PBT/PC共混物的断裂行为，实现材料强度与韧性的平衡，获得冲击强度高于900J/m，屈服应力大于50MPa的共混材料。本课题通过第三组分聚合物引入改变基体性质，从而改变增韧塑料断裂行为，实现对塑料协同增韧，指导高韧工程塑料合金开发、丰富高分子增韧理论有重要实用价值和理论意义。