聚乙二醇对环氧胶衣温度冲击开裂性能的影响

为开发一种满足航空环境要求的新型环氧胶衣,首先,研究了不同分子量、不同含量的聚乙二醇(PEG)改性环氧胶衣在室温下的冲击韧性及冲击断面形貌;然后,采用一种简单温度冲击试样模型,着重研究了PEG改性环氧胶衣在温度冲击(-50℃/30 min+90℃/30 min)下的开裂性能,并通过分析热膨胀及储能模量等的变化趋势对其进行了验证。结果表明:5wt% PEG-1000改性环氧胶衣的冲击强度比未改性环氧胶衣的提高了31.8%,达到最高值4.97 kJ·m-2;PEG-1000和PEG-2000改性环氧胶衣的冲击断面呈现出更明显的塑性变形形貌,胶衣的冲击韧性得到提高;15wt% PEG-400改性环氧胶衣在温度冲击下的宏观初始开裂性能达到最佳,平均初始开裂需要进行10.4次循环;改性环氧胶衣的耐开裂扩散性能基本上随着PEG分子量和含量的增加而提高,但裂纹宽度也会随PEG分子量的增加而扩大。 

Influences of polyethylene glycol on crack properties of epoxy gel coat under thermal shock

In order to develop a new type epoxy gel coat to meet the requirements of aeronautical environment, the impact toughness and impact fracture morphologies of epoxy gel coats modified with different molecular weights and different amounts of polyethylene glycol(PEG) at room temperature were investigated. Then, the crack properties of PEG modified epoxy gel coat under thermal shock(-50℃/30 min+90℃/30 min) were mainly investigated by using a simple thermal shock specimen model, and it was verified by analyzing the changing tendencies of thermal expansion and storage modulus etc. The results show that the impact strength of 5wt% PEG-1000 modified epoxy gel coat is enhanced by 31.8% comparing with that of unmodified epoxy gel coat, which reaches the highest value of 4.97 kJ·m^-2. More obvious plastic deformation morphologies appear on the impact fracture surfaces of PEG-1000 and PEG-2000 modified epoxy gel coats, and the impact toughness of gel coats increases. The macroscopic initial crack property of 15wt% PEG-400 modified epoxy gel coat under thermal shock reaches the best, average initial crack needs conducting 10.4 cycles. The properties of crack extension resistance for modified epoxy gel coat are basically improved with the increase of PEG molecular weight and content. However, the crack width will be amplified with the increase of PEG molecular weight.