Gas phase silica is extremely important, one of the high-tech superfine inorganic new materials due to its small particle size, specific surface area is big, therefore the surface adsorption power, surface energy, high chemical purity, good dispersion performance, heat resistance, resistance has specific performance, with its excellent stability, reinforcing, thickening and thixotropic, and unique features in the field of the academic disciplines, Has irreplaceable effect.

Application of high temperature vulcanized (HTV) silicone rubber

The use of gas phase silicon dioxide can be divided into organic silicon materials and other fields, in which the amount of organic silicon material accounted for nearly 60% of the total amount of gas phase silicon dioxide, silicone rubber is the most material in the use of gas phase silicon dioxide, its addition can be as high as 50%. Gaseous silicon dioxide mainly plays a reinforcing role in HVT silicone rubber. Because the molecular chain of silicone rubber is very supple and the interchain interaction force is weak, the strength of silicone rubber without reinforcement is very low, while the strength of silicone rubber reinforced by gaseous silicon dioxide can be increased up to 40 times.

The reinforcing effect of gaseous silica on 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 and the higher the structure, the better the reinforcing effect, and the higher the strength and hardness of vulcanized rubber. The tearing strength of vulcanized rubber is similar to the tensile strength, which increases with the reinforcement of gas phase silicon dioxide, first increases with the increase of the amount of gas phase silicon dioxide, and then decreases slightly after reaching the peak value.

In the mixing process, adding structural control agent or selecting gas phase silica after surface treatment to reduce the number of surface hydroxyl groups, so that the number of hydrogen bonds formed with silicone rubber decreases, so that the mixing time of the mixing rubber is shortened, the plasticity is increased, and the purpose of reducing the structural effect and improving the processing performance and storage stability is achieved.

Application of RTV silicone rubber

RTV silicone rubber can be divided into single component (RTV-1) and two component (RTV-2) in product form. In terms of vulcanization mechanism, it can be divided into two systems: condensation type and addition forming. Various forms of RTV silicone rubber need to be reinforced with fillers to have use value. At present, gaseous silica is the most used and most effective RTV silicone rubber reinforcement filler. Because 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 amount of gas phase silica is generally much less than that of high temperature vulcanized silicone rubber, and it is often used with other reinforcing and semi-reinforcing fillers to facilitate the construction operation.

RTV silicone rubber generally selects the gas phase silica with a relatively low specific surface area as filler. The silicone rubber without reinforcement is brittle after vulcanization, and the hardness of silicone rubber increases with the increase of the addition of silica.

When adding gaseous silica to RTV silicone rubber, attention must be paid to its dispersion in the polymer. Under the same dispersion conditions, the gas phase silica products with larger specific surface area generally have better transparency.