硅橡胶密封圈自然贮存条件下的老化机理研究

Study of the Ageing Mechanism of Silicone Rubber Seals under Natural Storage

通过自然贮存老化试验,研究了硅橡胶密封圈的老化性能。对自然贮存17年和未老化的硅橡胶密封圈进行拉伸疲劳试验,并且使用衰减全反射红外光谱分析其老化机理。实验结果表明,随着应变幅值的增加,两种材料的疲劳寿命均呈显著降低的趋势,未老化的硅橡胶密封圈疲劳寿命比自然贮存17年的硅橡胶密封圈长。同时随着应变幅值的增加,两种材料疲劳寿命的差异逐渐减小。红外光谱测试结果表明,Si-C的伸缩振动峰、橡胶分子链中甲基和亚甲基对称和不对称伸缩振动强度降低,Si-O-Si的伸缩振动峰、O-H的伸缩振动峰、C-OH面内弯曲振动峰、C-O-C对称伸缩振动峰强度增加,说明硅橡胶密封圈在空气作用下发生缓慢的氧化作用,Si-C、C-H键断裂,产生Si-O和C-O键,从而导致其力学性能降低。

This paper investigates the ageing performance of silicone rubber seals through natural storage ageing tests.Tensile fatigue tests were carried out on silicone rubber seals that had been stored naturally for 17 years and were not aged,and the ageing mechanism was analysed by attenuated total reflection infrared spectroscopy.The results showed that the fatigue life of the two materials decreased significantly with the increase of strain amplitude,and the fatigue life of the unaged silicone rubber seal rings were longer than that of the natural storage for 17 years.At the same time,with the increase of strain amplitude,the difference of fatigue life of the two materials gradually decreased.The results of the infrared spectroscopy test showed that the stretching vibration peak of Si-C,the symmetric and asymmetric stretching vibration intensity of methyl and methylene in the rubber molecular chain decreased.The stretching vibration peak of Si-O-Si,the stretching vibration peak of O-H,the bending vibration peak in the C-OH plane,and the symmetric stretching vibration intensity of C-O-C increased,indicating that slow oxidation occurred under the action of air.The Si-C and C-H bonds broke and the Si-O and C-O bonds were produced,resulting in the decrease in mechanical properties.