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

Thermal aging is the most important form of silicone rubber aging. The use environment of silicone rubber is in high-temperature air, and the combination of heat and oxygen leads to thermal aging. During the thermal oxygen aging process, high temperature promotes the oxidation of silicone rubber, while oxygen promotes the thermal degradation of silicone rubber.

The structural changes of silicone rubber during thermal oxygen aging can be divided into two categories: firstly, the thermal oxygen aging reaction leads to the degradation of molecular chains; Another type is cross-linking between molecular chains. Molecular chain breakage causes rubber to become sticky after aging; After aging, cross-linked rubber will harden, causing a decrease in the mechanical properties of the rubber and ultimately leading to failure. Air heating, vulcanized silicone rubber cross-linking, and the decrease in elongation at break is much greater than the tensile strength.