1.Chemical composition


(1).Main chain and side base


The main chain is the main frame of silicone rubber, which has a decisive effect on the thermal aging of silicone rubber.The main chain consists of silicon-oxygen compounds and is arranged in a spiral. It has greater polarity and flexibility. Consequently, it is susceptible to the destruction of the main chain and the oxidation of the side group at high temperatures, which leads to a gradual softening of silicone rubber and loss of its consumer value.If the main chain of silicone rubber consists of different structures, their heat resistance is also very different.Introduction of phenylene, cyclodisilazane, auxiliary phenyleether, auxiliary benzene group, The carbon decaboryl group and other groups in the main chain can significantly suppress the possibility of a cyclization decomposition reaction and increase the overall thermal stability of the material.As for the side groups, when the side groups of vinyl silicone rubber are phenyl, methyl, ethyl, propyl and butyl, oxidation will occur sequentially in a high temperature environment, which will lead to a decrease in the heat resistance of the material. In addition, according to research, with an increase in the number of alkyl groups in the side chain, the heat resistance of silicone rubber also decreases.For example, the heat resistance of dimethylsilicon rubber is better than that of butylsilicon rubber.