硬段含量对快速固化聚氨酯修补胶性能的影响

制备了不同硬段含量(18%~34%)的快速固化聚氨酯修补胶(PRA)，考察了硬段含量对PRA的固化时间、力学性能、耐热性能、耐水性能和耐磨性能的影响。结果表明：当硬段含量由18%增加到34%时，PRA的氢键化程度增大，固化速度加快，拉伸强度、撕裂强度和剪切强度增大，断裂伸长率减小；随着硬段含量的增加，总体上PRA的起始分解温度提高，硬段热失重率增大，软段热失重率减小；硬段含量对PRA吸水率的影响很小，浸水7d后PRA的力学性能与浸水前相比有所下降；随着硬段含量的增加，PRA的磨耗体积先减小后增大，在硬段含量为26%和30%时磨耗体积较小；硬段含量为30%的PRA的综合性能较好，其固化时间为50s，拉伸强度为19.94MPa，断裂伸长率为460%，撕裂强度为70.72kN/m，剪切强度为1.87MPa，阿克隆磨耗体积为47mm³。

Effect of the hard segment content on the performance of fast-curing polyurethane repair adhesives

Fast-curing polyurethane repair adhesives (PRA) with different hard segment contents (18%-34%) were prepared. The effects of hard segment content on the curing time, mechanical properties, heat resistance, water resistance and wear resistance of PRA were investigated. The results show that when the hard segment content increases from 18% to 34%, the degree of hydrogen bonding in PRA increases, the curing speed increases, the tensile strength, tear strength and shear strength all increase, whilst the elongation at break decreases. With the increase of hard segment content, the initial decomposition temperature of PRA increases, the thermal weight loss rate of hard segments increases, and the thermal weight loss rate of soft segments decreases. The hard segment content had little effect on the water absorption ability of PRA. The mechanical properties of PRA decreased after immersion in water for seven days. With increasing hard segment content, the wear volume of PRA initially decreases and then increases, and the wear volume is small when the hard segment content is 26% and 30%. The optimal overall performance of PRA is obtained with a hard segment content of 30%. Its curing time is 50 s, the tensile strength is 19.94 MPa, the elongation at break is 460%, the tear strength is 70.72 kN/m, the shear strength is 1.87 MPa and the Akron wear volume is 47 mm³.