Fumed silica is one of the extremely important high-tech ultra-fine inorganic new materials. Because of its small particle size, it has large specific surface area, strong surface adsorption force, 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 plays an irreplaceable role.

Applications in High Temperature Vulcanization (HTV) Silicone Rubber
The use of fumed silica can be divided into organosilicon materials and other fields, among which the amount used in organosilicon materials accounts for nearly 60% of the total amount of fumed silica, and silicone rubber is the most used material of fumed silica in organosilicon materials , its addition can be as high as 50%. Fumed silica mainly plays a reinforcing role in HVT silicone rubber. Since the molecular chains of silicone rubber are very supple and the interaction force between chains is weak, the strength of unreinforced silicone rubber is very low. Strong silicone rubber that is up to 40 times stronger.

The reinforcement of fumed silica to HTV silicone rubber is affected by its particle size, relative area and structure. Generally, the smaller the particle size, the higher the specific surface area, the higher the structure, the better the reinforcing effect, and the vulcanized rubber The higher the strength and hardness. The change of tear strength of vulcanized rubber is similar to that of tensile strength, which increases with the reinforcement of fumed silica, increases first with the increase of the amount of fumed silica, reaches the peak and then decreases slightly.

Adding a structure control agent or selecting surface-treated fumed silica to reduce the number of surface hydroxyl groups during the mixing process reduces the number of hydrogen bonds formed with silicone rubber, shortens the mixing time of the rubber, increases the plasticity, and reduces the Structuring effect for the purpose of improving processability and storage stability.

Application of room temperature vulcanization (RTV) silicone rubber
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. . Various forms of room temperature vulcanized 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 reinforcing filler. Since RTV silicone rubber is generally used as a sealing material for pouring, caulking, coating, etc., in order to maintain the viscosity and fluidity before vulcanization, the amount of fumed silica is generally much less than that of high-temperature vulcanized silicone rubber, and it is often combined with other supplements. Strong and semi-reinforcing fillers are used together to facilitate construction operations.

RTV silicone rubber generally uses fumed silica with a relatively low specific surface area as a filler. Unreinforced silicone rubber is brittle after vulcanization. After adding fumed silica for reinforcement, the hardness of silicone rubber increases with the amount of silica added.

When adding fumed silica to RTV silicone rubber, attention must be paid to its 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 obtained in other fields, such as coatings, inks, medicine, cosmetics, and chemical mechanical polishing (CMP). Wide application, the development prospect is also very bright.