The toughness of the epoxy resins is modified by liquid crystalline copolyester PET-PHB.The morphologies of the fracture surface were observed by scanning electron microscope (SEM).The relationships between the morphologies and mechanical properties were discussed. The results revealed that the moduli, tensile and impact strengths of the modified epoxy resins are much higher than those of the unmodified epoxy resin. The maximum values have been reached in the tensile and impact strength of the modified epoxy resins by adding PET-PHB copolyester of 10%.At the same time,an uniformly network microstructure emerged on the fracture surface of the toughened epoxy resins, which is obviously different from that of the unmodified epoxy resin. It is believed that the formation of the uniformly network microstructure resulted in the significant improvement of impact and tensile strength of the epoxy resins.%采用熔融共混方法，用热致液晶PET-PHB共聚酯对环氧树脂进行增韧改性，并研究了共混体系的力学性能．借助扫描电镜，对材料断裂面的形态结构进行了分析，探讨了体系的形态结构与冲击性能之间的关系．研究结果表明，改性材料的弹性模量高于纯环氧树脂，其冲击强度及拉伸强度均有大幅度提高．当PET-PHB共聚酯的加入量为10%时，环氧改性材料的拉伸强度及冲击强度均为最大值．此时，改性材料的断面形态呈微观网络分布，明显不同于未改性环氧树脂脆性断裂的台阶型结构．
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