Room temperature vulcanized (RTV) silicone rubber can be divided into two categories in terms of product morphology: single component (RTV-1) and two component (RTV-2); from the perspective of vulcanization mechanism, it can be divided into two systems: condensation type and addition type. At present, fumed silica is the most effective RTV silicone rubber reinforcing filler. As RTV silicone rubber is generally used as pouring, caulking, coating and other sealing materials, in order to maintain the viscosity and fluidity before vulcanization, the addition amount of fumed silica is generally less than that of high temperature vulcanized silicone rubber, and it is often used together with other reinforcing and semi reinforcing fillers to facilitate construction operation.

RTV silicone rubber generally uses fumed silica with relatively low specific surface area as filler. After vulcanization, the unreinforced silicone rubber is brittle. After the addition of fumed silica, the hardness of silicone rubber increases with the increase of silica content.

When adding fumed silica to RTV silicone rubber, we must pay attention to its dispersion in polymer. Under the same dispersing conditions, the products with large specific surface area have better transparency.