密封用发泡硅橡胶的压缩老化及寿命评估

Compression aging and lifetime assessment of foamed silicone rubber for sealing

采用压缩热老化法对密封用发泡硅橡胶材料在180℃下进行不同时间的加速老化,对撕裂性能、质量损失率、微观形貌、红外光谱等进行测试分析,并以压缩回弹率作为重要参数对密封用发泡硅橡胶材料进行了寿命评估。并以压缩老化回弹率实验数据评估了发泡硅橡胶材料的使用寿命。结果表明,随着老化时间的增加(36 h内),撕裂强度略微增加,当老化时间大于72 h后,撕裂强度下降;随着时间的不断增加,质量损失率逐渐增大,在144 h内从0增加到5.5%;发泡硅橡胶表面分子链在180℃热老化下硅橡胶分子链的主链和侧链均发生了断裂,而内部分子链的主链以交联为主,侧链以断裂为主;随着老化时间的增加,发泡硅橡胶表面出现裂缝和气孔,而内部的泡孔由大逐步变小;在23、35、40℃下的使用寿命分别为15.65、7.01、5.11年。

A compression thermal aging method was employed to accelerate the aging of foamed silicone rubber for sealing at 180ºC over different time.The tearing performance,mass loss rate,microstructure and infrared spectroscopy of the aged rubber samples were analyzed,and their lifetime was evaluated by using compression rebound rate as an important parameter.The results indicated that the foamed silicone rubber exhibited a slight increase in the tear strength with an in⁃crease in aging time(within 36 h),followed by a decrease after aging for over 72 h.With a continuous increase in the ag⁃ing time,there is a gradual increase in the mass loss rate of the foamed silicone rubber from 0 to 5.5 wt%within 144 h.The infrared spectroscopic analysis indicated that the main and side chains on the surface molecular chain of the foamed silicone rubber were broken after thermal aging at 180℃.However,its main chains in the internal part were mainly cross⁃linked,but its side chains were mainly broken.The morphological observation indicated that there were cracks and pores appearing on the surface of the foamed silicone rubber with an increase in aging time,whereas the internal pores de⁃creased gradually from a large size to the small one.The service lifetime of the foamed silicone rubber material was evalu⁃ated by using experimental data on the compression aging rebound rate.The results showed that the service lifetimes were 15.65,7.01,and 5.11 years at 23,35,and 40℃,respectively.