Silicone rubber is generally highly saturated structure, low vulcanization activity, so usually can not be vulcanized with sulfur, the most common and most commonly used vulcanizing agent for organic peroxide. Silicone rubber can also use high-energy rays for radiation vulcanization, radiation vulcanization and peroxide vulcanization mechanism is the same, are free radical reaction and crosslinking.

Dimethyl silicone rubber molecule does not contain vinyl, is saturated rubber, usually are used for the vulcanizing agent of highly reactive peroxide, peroxide free radicals to capture the hydrogen on the methyl of the silicone rubber to form macromolecular free radicals, and then macromolecular free radicals and then the combination of that is the formation of cross-linking, such as dibenzoyl peroxide as the vulcanizing agent.

According to the high and low peroxide vulcanizing activity, the commonly used peroxides are divided into two categories: general-purpose and vinyl-specific. General-purpose activity is higher, on a variety of silicone rubber can play a role in vulcanization, such as benzoyl peroxide (BP), 2?4-dichlorobenzoyl peroxide (DCBP), tert-butyl peroxybenzoate (TBPB), that is, belong to this type. Vinyl-specific activity is lower, only for vinyl-containing silicone rubber vulcanization, such as di-tert-butyl peroxide (DTBP), di-isopropyl peroxide (DCP and odorless DCP), 2?5-dimethyl-2?5-di-tert-butyl peroxyhexane (DBPMH) and so on belong to this type. This type. Dibenzoyl peroxide is often made into a 50% active ingredient silicone cream to ensure production safety and improve its dispersion in the rubber. Its decomposition products for benzene, benzoic acid and carbon dioxide, is volatile, in a section of the vulcanization must be pressurized, and because the decomposition products contain acidic substances, so the dosage should not be too much so as not to reduce the heat resistance of the products, this product is not suitable for the manufacture of thick-walled model products. Generally 100 parts of dimethyl silicone rubber with dibenzoyl peroxide silicone oil paste 4 to 6 parts, vinyl silicone rubber dosage of 0.5 to 2 parts.

2.4-Dichlorodibenzoyl peroxide compared with dibenzoyl peroxide, its decomposition temperature is lower than that of dibenzoyl peroxide, while the decomposition rate is higher, due to the decomposition temperature is low, so the charring performance is not good, so the dosage of this substance should be as little as possible. Its decomposition products are 2.4-dichlorobenzoic acid and 2.4-dichlorobenzene, which are relatively non-volatile, so it can avoid air bubbles without pressure when vulcanizing, and it is especially suitable for continuous vulcanization with hot air at atmospheric pressure of pressed products. The dosage is similar to dibenzoyl peroxide.

Dibenzoyl peroxide, 2.4-dichlorodibenzoyl peroxide belongs to aryl peroxide, it can not be used in carbon black-containing rubber, because carbon black interferes with the vulcanization of peroxide. Light-colored rubber has a strong tendency to scorch, and the acid in its decomposition products will damage the heat resistance of silicone rubber products in sealing systems.

Di-tert-butyl peroxide is effective for vinyl silicone rubber, not easy to burn and vulcanized rubber compression deformation is small, good physical and mechanical properties. Its disadvantage is that the vapor pressure is high, so the volatility is also high, in the rubber storage process is very easy to volatile. This product can be used for modeling products. And can be used for molding thick products of rubber and rubber containing carbon black. The dosage is generally 0.5~1 part.

Diisopropyl peroxide DCP and odorless DCP, and 2.5-dimethyl-2.5-di-tert-butyl peroxyhexane are not volatile, easy to use, low compression deformation of vulcanized rubber, and are especially stable in the vulcanized rubber of sealing products because they do not decompose the products with carboxyl group. They are suitable for molded thick products, products bonded with metal and injected products, as well as for rubber materials containing carbon black, with a wide range of applications. When 2.5-dimethyl-2.5-di-tert-butyl peroxyhexane is used, the vulcanized rubber has a high elongation. When using diisopropyl benzene peroxide, its decomposition product has an odor, which remains in the product for a long time, but when using 2.5-dimethyl-2.5-di-tert-butylhexyl peroxide, this disadvantage can be avoided. These two peroxides obtained from the vulcanized rubber tear strength is low. Its dosage is generally 0.5 ~ 1.

The amount of peroxide should not be too large, when more than the appropriate amount will make the vulcanized rubber elongation, tear strength and other properties decline. This downward trend is especially true for those who use 2.4-dichlorodibenzoyl peroxide and dibenzoyl peroxide.
 
Vinyl-containing silicone rubber raw rubber in addition to the use of peroxide vulcanization vulcanization, but also for the addition of vulcanization. Nowadays, the vulcanization of vulcanization vulcanizing agent is mainly used for the peroxide or polymer containing silicone hydroxyl group. si-H group and vinyl addition and realize vulcanization, in this reaction, usually use the platinum complex as a catalyst.