The vulcanizing agents used for thermal vulcanization of silicone rubber mainly include organic peroxides, aliphatic azo compounds, inorganic compounds, high-energy rays, etc. Among them, organic peroxides are the most commonly used. This is because organic peroxides are generally stable at room temperature, but can rapidly decompose to generate free radicals at higher vulcanization temperatures, thereby crosslinking silicone rubber.

Peroxides can be divided into two categories according to their activity. One type is general-purpose type, that is, with high activity, which can vulcanize various silicone rubbers; the other type is vinyl-specific type, that is, low activity, which can only vulcanize vinyl-containing silicone rubber.

In addition to the above general distinctions between the two classes of peroxides, each has its own characteristics. Vulcanizing agent BP is the most commonly used curing agent for molded products. It has fast curing speed and high production efficiency, but it is not suitable for the production of thick products.

Vulcanizing agent DCBP is not easy to volatilize its product, and bubbles will also be generated when vulcanized without pressure. It is especially suitable for continuous hot air vulcanization of extruded products, but its decomposition temperature is low, it is easy to cause scorch, and the storage time of rubber compound is short.

When the rubber compound is stored at room temperature, the vulcanizing agent will volatilize, and it is best to use the molecular sieve as a carrier. The vulcanizing agent DTBP does not react with air or carbon black, and can be used in the manufacture of conductive rubber and products with difficult molding operations. It is not volatile at room temperature, and its decomposition products are highly volatile, which can shorten the secondary vulcanization time. The vulcanizing agent DCP does not volatilize at room temperature, and has the characteristics of a vinyl-only type. At the same time, the decomposition product has low volatility, and can be used for vulcanization in situations where the external pressure is small.

The amount of peroxide used is affected by a number of factors. For example, raw rubber variety, filler type and amount, processing technology, etc. Generally speaking, as long as the desired crosslinking can be achieved, the vulcanizing agent should be kept as little as possible. However, the actual dosage is much higher than the theoretical dosage, because the influence of various processing factors must be considered, such as uneven mixing, loss of peroxide in the storage of the rubber compound, and resistance of air and other compounding agents during vulcanization.