端环氧基聚氨酯的合成及其与环氧树脂共混物的性能

Synthesis of Liquid Epoxy-terminated Polyurethane(ETPU)and Mechanical Properties of Epoxy Resin Blend with ETPU

合成了四种不同数均分子量的聚丙二醇型端环氧基聚氨酯(ETPU),标记为ETPU700、ETPU1000、ETPU1500及ETPU2000,并考察了其与环氧树脂共混物的物理机械性能。采用FT-IR与~1HNMR对端环氧基聚氨酯的结构进行了表征。ETPU/EP的力学性能随ETPU的分子量以及用量的变化而改变:对于ETPU1000、ETPU1500和ETPU2000,ETPU/EP的拉伸强度与冲击值先随ETPU添加量的增加而增加,当ETPU的添加量超过临界值——分别为3phr、5phr、1phr后,会导致拉伸强度与冲击值的下降;对于ETPU700,ETPU/EP的拉伸强度随ETPU添加量的增加而下降,超过临界添加量7phr后拉伸强度上升,而冲击值则随ETPU添加量的增加而缓慢增加。SEM分析表明ETPU/EP呈两相结构,橡胶颗粒粒径随ETPU添加量的上升而增大,且断面呈典型的韧性断裂。DMA测试结果表明ETPU/EP的T_g降低,Tanδ增大,说明ETPU/EP固化后的网络柔韧性增加。

Poly（ethylene glycol）-based epoxy-terminated polyurethanes （ETPU） with different number- average molecular weights, i.e. ETPUT00, ETPU1000, ETPU1500 and ETPU2000, were synthesized and then added in epoxy （EP） to enhance its toughness. The FT-IR evidenced the occurrence of oxazolidone as the result of the reaction between epoxy and isocyanate group. Mechanical property of the ETPU/EP composite varies with the molecular weight and content of the ETPU. For the ETPU1000/PE, ETPU1500/PE and ETPU2000/PE, each tensile strength and impact value increase first with the addition of ETPU reaching the maximum at each critical concentration, 5phr, 7phr and lphr, respectively, then decrease with higher concentration due to larger particles formation; On the contrary, for the ETPU700/PE, the tensile stress decreases with the addition of ETPU until a critical concentration of 7phr, followed by an increase with further content increase of EUPT, but the impact value increases monotonically with the addition of ETPU. SEM micrographs showed that these ETPU/EP^s exhibit a two-phase morphology and the rubber particles grow with the increase of ETPU content. DMA shows that the incorporation of ETPU lowers TK and raise Tan3, indicating the network of ETPU/EP more flexible.