Silicone rubber is a low unsaturation linear polysiloxane elastomer whose main chain is composed of silicon atom and oxygen atom alternately and whose side chain is methyl or vinyl. According to the vulcanization mechanism, it can be divided into three types: free radical crosslinked vulcanized silicone rubber, polycondensation room temperature vulcanized silicone rubber and addition reaction low temperature vulcanized silicone rubber.

(1) Vulcanization system of heat vulcanized silicone rubber
Heat vulcanized silicone rubber can be divided into organic peroxide, aliphatic azo compounds, inorganic compounds and high energy radiation curing methods. One of the most commonly used is the organic peroxide curing system. Because organic peroxides are generally stable at room temperature, they can decompose rapidly at higher vulcanization temperature (above 150 ℃) to produce vulcanization. Under the initiation of organic peroxide, the vulcanization reaction of the organic side chain group of rubber formed C-C bond crosslinking. The more content of side chain such as vinyl group, the easier vulcanization and the higher degree of crosslinking.

Organic peroxides for silicone rubber can be divided into two types: general purpose type and special purpose type. The former has higher activity and can cure all kinds of silicone rubber, while the latter has lower activity and can only cure vinyl silicone rubber.

The curing agent BP has fast curing speed, and is often used in molded products and continuous curing products, not thick wall products. DCBP has low decomposition temperature and only produces low vapor pressure products. It is especially suitable for hot air continuous vulcanization of extruded products. The compound has short storage time and is easy to scorch. The vulcanizing agents BP and dCBP are explosive, and the paste dispersion of silicone oil and other products (generally 50%) is commonly used for safe operation and dispersion.

The curing agent DTBP is easy to volatilize (boiling point 110 ℃), and it is suitable for molecular sieve adsorption function. It will not react with air or carbon black. It can be applied to conductive rubber and products difficult to mold.

The curing agent dbpmh is very volatile at the curing temperature, which can shorten the second stage curing time.

DCP is a special vinyl curing agent with low volatile decomposition products, which is suitable for curing under low external pressure.

TbpB is suitable for sponge products.

The decomposition time of various peroxides in silicone rubber at 140 ℃.