Abstract: Epoxy encapsulating materials grafted and modified with polyurethane（PU）was prepared by reaction of —NCO—terminated PU prepolymer with epoxy resin（EP）. The FTIR indicated that the reaction between —NCO—terminated PU prepolymer and the secondary hydroxy in epoxy resin has completed. Effect of PU content on viscosity of resin and the change of temperature in curing process was investigated. The impact strength and flexural strength of materials were all improved by add PU prepolymer content of 5% (mass fraction)，increased 30% and 200% compared with the neat epoxy resin respectively. The glass-transition temperature of materials wasn’t decreased. Lastly，toughen mechanism was analyzed by SEM.

摘要： 以异氰酸酯封端的聚氨酯预聚体（PU）与环氧树脂（EP）发生反应，制备了聚氨酯接枝改性环氧灌封材料。FTIR表明异氰酸酯封端的聚氨酯预聚体与环氧树脂中的仲羟基完全反应，同时考察了活性稀释剂用量对树脂黏度的影响及固化过程中温度的变化。聚氨酯预聚体的加入，使材料的冲击强度和弯曲强度都有所升高，当聚氨酯质量分数为5％时，材料的弯曲强度提高了30%，而冲击强度提高了近200%，玻璃化转变温度没有降低，SEM分析了其增韧机理。