According to the thermal aging mechanism of silicone rubber vulcanizate, there are several methods to improve its thermal aging performance, as follows:
(1) Change the composition of the side chains of silicone rubber, such as introducing phenyl, to prevent cross-linking or decomposition of molecular chains in silicone rubber due to the decomposition of the side chains. This is because phenyl is not easily oxidized and spatial hindrance is formed in the silicon chain, making it more difficult for the organic silicon chain to be decomposed. Moreover, due to its greater conjugation and steric hindrance effects, the thermal decomposition temperature is higher.
(2) By introducing large volume segments into the molecular chain of silicone rubber, the thermal stability of the crosslinking bond of the vulcanizate is improved, such as carbon, decyloxy, benzene, phenyl ether, and cyclic diamine groups.
(3) Add heat-resistant additives to the adhesive to prevent side chain oxidation crosslinking and main chain cyclization decomposition, such as iron oxide, dioxane, hexaphenylcyclotrisilane, etc.

1. Add metal oxide antioxidants
The oxidative aging mechanism of silicone rubber is mainly caused by the oxidation reaction of the side chains caused by free radicals. If this chain reaction is prevented, the oxidation process will stop. Fe2O3 is the most commonly used antioxidant, typically added in amounts of 3 to 5 parts. According to relevant research reports, composite metal oxides prepared by liquid phase co precipitation method can significantly improve the heat resistance of silicone rubber. Research has shown that iron tin composite metal oxides are more effective in improving the heat resistance of silicone rubber than single iron oxide and tin oxide. This is because the crystal structure of the prepared composite metal oxide has undergone changes, and their respective antioxidant effects have synergistic effects. It can inhibit oxidation and improve the heat resistance of silicone rubber.

2. Adding Silazane
Silazane can significantly improve the heat resistance of silicone rubber. The mechanism is that silazane can effectively inhibit the degradation of the main chain, eliminate trace moisture in silicone rubber, and make the heat resistance of silicone rubber reach 350 ℃. The higher the apparent activation energy and hydrolysis stability of silazane hydrolysis, the better the thermal stability of silicone rubber. The commonly used ones include: hexamethyldisilazane, hexamethylcyclotrislazane, etc.

3. Add silicone resin
Silicone resin is a highly cross-linked network structure polysiloxane, which is a thermosetting resin. Its main chain is composed of silicon oxygen bonds, with a structure similar to quartz and glass, and has excellent thermal oxidation stability. When heated at 205 ℃ for 42 hours, the weight loss of silicone resin is only 2% to 8%, and after heating at 350 ℃ for 24 hours, the weight loss is less than 20%.