Silicone rubber refers to the main chain is alternately composed of silicon and oxygen atoms, silicon atoms are usually connected with two organic groups of rubber. Ordinary silicone rubber is mainly composed of silicone chains containing methyl groups and a small amount of vinyl.

Thermal aging is the most important form of silicone rubber aging. The use environment of silicone rubber is in high temperature air, resulting in thermal aging due to the combination of heat and oxygen. In the process of hot oxygen aging, high temperature promotes the oxidation of silicone rubber, and oxygen promotes the thermal degradation of silicone rubber.

The structural changes of silicone rubber in the process of hot oxygen aging can be divided into two categories: first, hot oxygen aging reaction leads to molecular chain degradation; The other is cross-linking between molecular chains. The breakage of molecular chain causes the rubber to become sticky after aging. Crosslinked rubber will harden after aging, which will reduce the mechanical properties of rubber and eventually lead to failure. When the air is heated and the vulcanized silicone rubber is cross-linked, the reduction of elongation at break is much greater than the tensile strength.