苯基硅橡胶分子结构与耐高温性能关系的试验与模拟

通过试验与分子模拟相结合的方法研究了单苯基硅橡胶和二苯基硅橡胶分子结构对其耐高温性能的影响。结果表明，在400 ℃高温老化前期，二苯基硅橡胶体系和单苯基硅橡胶体系的硬度、力学性能及耐高温性能差别不明显，而经过10次400 ℃高温循环老化后，二苯基硅橡胶体系力学性能与质量保持率更高，耐高温性能更好。此外，分子模拟结果证实了在675 K下二苯基硅橡胶中苯基链段的Si—O解离能更高，二苯基硅橡胶体系的位阻效应更强，自由体积分数更小，与氧气接触的概率更低，在长期的高温环境中具有更高的热稳定性。

Experiment and simulation of the relationship between molecular structure and high temperature resistance of phenyl silicone rubber

The influence of the molecular structure of monophenyl and diphenyl silicone rubber on the high temperature resistance was studied by combining experiment and molecular simulation. The results showed that hardness, mechanical properties and high temperature resistance of the diphenyl silicone rubber system were not significantly different from those of the monophenyl silicone rubber system at the early aging stage of high temperature of 400 ℃, but after 10 aging cycles of high temperature of 400℃, mechanical properties and mass retention rate of the diphenyl silicone rubber system were higher, and high temperature resistance was better. In addition, the results of molecular simulation confirmed that Si—O of diphenyl silicone rubber has higher dissociation energy at 675 K, and the diphenyl silicone rubber system has stronger steric effect, smaller free volume fraction, lower probability of contact with oxygen, and higher thermal stability in long-term high temperature environment.