玻璃纤维/环氧乙烯基酯树脂复合材料的层间增韧及其低温下低速冲击性能

采用真空辅助成型工艺(VARI)制备了四种无纺布(聚酰胺(PA)、聚氨酯弹性体橡胶(TPU)、乙烯-醋酸乙烯共聚物(EVA)、共聚酯(PEs))层间改性的玻璃纤维/环氧乙烯基酯树脂(GF/EVER)复合材料层合板。在温度为20℃下进行落锤冲击实验，对比分析了不同层间改性的GF/EVER复合材料层合板的低速冲击响应特性和抗冲击性能；利用超声C扫描和SEM分析了其冲击损伤机制。通过对复合材料层合板的冲击损伤面积、凹坑深度、最大接触力、冲击后剩余压缩强度(CAI)值的对比分析可知，经TPU和PEs无纺布层间改性的GF/EVER复合材料抗冲击性能较佳。不同的无纺布和基体树脂生成的界面相与纤维的结合程度不尽相同。层间改性的GF/EVER复合材料的冲击损伤机制为冲击正面表层基体树脂的开裂，其内部的分层和冲击背面的分层劈裂或纤维断裂；同时，进一步研究了经TPU和PEs改性的GF/EVER复合材料在低温下(?100℃和?45℃)的低速冲击性能，结果表明，随着温度的降低，GF/EVER复合材料的冲击损伤面积随之增大，CAI值随之减小，这可能是GF/EVER复合材料在低温下层间残余热应力和基体树脂脆化效应综合作用的结果。 

Interlaminar toughening of glass fiber/epoxy vinyl ester resin composite and its low-velocity impact properties at low temperature

Four kinds of glass fiber/epoxy vinyl ester resin(GF/EVER)composite laminates interlayer toughened by polyamide(PA),polyurethane(TPU),vinyl ester copolymer(EVA)and co-polyester(PEs)nonwoven fabrics were prepared by vacuum assisted resin infusion(VARI)process.The drop hammer impact test was carried out at temperature of 20℃,and the low-velocity impact response and impact resistance of the different GF/EVER composite laminates were compared and analyzed.The fracture mechanism was further studied by means of ultrasonic C-scan and SEM.The results indicate that the GF/EVER composite laminates modified by TPU and PEs nonwoven fabrics have better impact resistance through the comparison of impact damage area,dent depth,maximum contact force and residual compression strength(CAI).The interface phase and fiber binding degree of different non-woven fabrics and matrix resins are different.The impact damage mechanism of GF/EVER composite laminates is the cracking of matrix resin on the surface of impact surface,the delamination inside the composite laminate and the delamination cleavage or fiber fracture on the back of impact surface.Meanwhile,the low-velocity impact performance of GF/EVER composite laminates modified by TPU and PEs nonwoven fabrics was further studied under impact test at low temperature(-100℃,-45℃).The results show that the impact damage area will be increased and CAI will be decreased with the decrease of temperature.This may be the result of the combined action of the interlaminar residual thermal stress of GF/EVER composites and the embrittlement effect of matrix resin at low temperature.