Fumed silica is one of the most important high-tech ultra-fine inorganic new materials. Because of its small particle size, it has large specific surface area, strong surface adsorption, large surface energy, high chemical purity, good dispersion performance, thermal resistance, Resistance and other aspects have specific properties. With its superior stability, reinforcement, thickening and thixotropy, it has unique characteristics in many disciplines and fields and has an irreplaceable role.

The use of fumed silica can be divided into organic silicon materials and other fields. Among them, the amount of fumed silica in organic silicon materials accounts for nearly 60% of the total amount of fumed silica. Silicone rubber is the most used material in organic silicon materials. , the addition amount can be as high as 50% or more. Fumed silica mainly plays a reinforcing role in HVT silicone rubber. Because the molecular chain of silicone rubber is very flexible and the interaction force between chains is weak, the strength of unreinforced silicone rubber is very low. Strong silicone rubber, its strength can be increased by up to 40 times.

The reinforcement of fumed silica to HTV silicone rubber is affected by its particle size, comparative area and structure. Generally, the smaller the particle size, the higher the specific surface area, the higher the structure, and the better the reinforcement effect. The higher the strength and hardness. The change of tear strength of vulcanizate is similar to that of tensile strength, both of which increase with the improvement of the reinforcement of fumed silica, increase first with the increase of the amount of fumed silica, and then decrease slightly after reaching the peak. In the mixing process, adding a structure control agent or selecting surface-treated fumed silica reduces the number of surface hydroxyl groups, which reduces the number of hydrogen bonds formed with the silicone rubber, shortens the mixing time of the rubber compound, increases the plasticity, and reduces the Structural effect for the purpose of improving processability and storage stability.

Room temperature vulcanization (RTV) silicone rubber is divided into two categories: one-component (RTV-1) and two-component (RTV-2) in terms of product form; in terms of vulcanization mechanism, it is divided into two systems: condensation type and addition type . All forms of RTV silicone rubber need to be reinforced with fillers to be useful. At present, fumed silica is the most used and most effective RTV silicone rubber reinforcement filler. Since RTV silicone rubber is generally used as a sealing material such as casting, caulking, and coating, in order to maintain the viscosity and fluidity before vulcanization, the amount of fumed silica added is generally much less than that of high-temperature vulcanized silicone rubber, and it is often combined with other fillers. Strong and semi-reinforcing fillers are used together to facilitate construction operations.

RTV silicone rubber generally uses fumed silica with relatively low specific surface area as filler. Unreinforced silicone rubber is brittle after vulcanization. After adding fumed silica to reinforce, the hardness of silicone rubber increases with the increase of the amount of silica added. When adding fumed silica to RTV silicone rubber, attention must be paid to the degree of dispersion in the polymer. Under the same dispersion conditions, fumed silica products with larger specific surface area generally have better transparency.

To sum up, fumed silica is an essential reinforcing material for silicone rubber. Due to its unique properties, it is also used in other fields, such as coatings, inks, medicine, cosmetics, and chemical mechanical polishing (CMP). It has been widely used, and the development prospect is also very bright.