混合型固化剂对环氧树脂室温和低温力学性能的影响

研究了一种刚性和柔性胺混合型固化剂（芳香胺DETD和聚醚胺D-400）固化环氧树脂浇铸体的力学性能、材料断裂表面的微观形貌和玻璃化转变温度等性能。结果表明:当D-400加入量占固化剂总量的40%时，其室温拉伸强度呈现最大值，为82.52 MPa，弹性模量为2.30 GPa，与未加D-400的体系相比分别提高了6.3%和14.4%，其低温冲击强度提高了14%。对冲击断面形貌进行扫描电子显微分析表明:D-400的加入致使断口形貌变得粗糙，抗开裂能力得到提高。热分析实验结果显示，体系的玻璃化转变温度随着D-400含量的增加而降低。此外，还探讨了环氧树脂体系低温增韧机制。 

RT and cryogenic mechanical properties of epoxy resins cured with mixed curing agent

The mechanical properties，morphologies of the fractured surfaces and the glass transition temperature were investigated for the epoxy resins cured with a mixed curing agent (aromatic diamine DETD and amine-terminated polyether D-400). The results show that with the addition of 40% relative mass fraction of D-400，the epoxy resin at room temperature exhibits the highest tensile strength of 82.52 MPa and Young‘s modulus of 2.30 GPa. And the tensile strength of the composites is enhanced by 6.3% while Young’s modulus by 14.4%. In addition，the cryogenic impact strength is enhanced by 14% at this content. SEM analysis of tensile fracture surfaces shows that the fractography tends to be irregular with the increase of flexible amine content，indicating that the fracture resistance is increased. Thermal analysis of the specimens shows that the glass transition temperature decreases with increasing the relative content of D-400. Finally，the mechanism of toughened epoxy resins at cryogenic temperature is discussed.