The impact of the colorants on the aging properties of HTV silicone rubber

The sheath and the shed in China are made of high temperature vulcanized (HTV) silicone rubber. The ferric oxide powder is widely used as red colorant, and it cannot disperse uniformly in the rubber for the reason that the ferric oxide powder is inorganic. In the paper, adding way and the amount of the ferric oxide powder are changed in the specimen-making process. Through hot air aging test, the changes of the specimen´s electrical performances, mechanical properties and microstructure are considered, so the influence of the colorant on the specimen´s property under hot air environment has been discussed. The results show that color masterbatch which is made of ferric oxide in advance, added in the rubber mixing process can improve the dispersion of the ferric oxide in the rubber, so that the ferric oxide can help reduce degradation of performance due to thermal-oxidative-aging. The radicals which are produced in silicone rubber´s aging process could be trapped by the iron ions, which can be oxidated by oxygen in the air soon, and the amount of iron ions are not changed before and after the reaction. Therefore, increasing the content of iron oxide has no significant effect to improve the heat aging performance of the silicone rubber.