Fumed white carbon black is an important inorganic functional material with a wide range of applications. It is mainly used as a reinforcing agent in silicone rubber and special rubber, and its reinforcing effect even exceeds that of carbon black. After adding fumed silica to silicone rubber, the tensile strength of the rubber compound can be increased by about 20 times, the tearing strength can be increased by 40 times, and the transparency is high. Fumed silica is used in nitrile rubber, hydroxynitrile rubber, chloroprene rubber, EPDM rubber, and the performance of rubber parts for oil fields is compared with that of the rubber compound using precipitated silica or carbon black. It has higher hardness, tensile strength, better wear resistance and lower water swellability.

The reinforcing performance of fumed silica to rubber mainly depends on the size, structure and surface chemistry of silica particles.

Under normal circumstances, the size of the particles is expressed by the average particle diameter or specific surface area, and the measurement method is electron microscopy or BET adsorption method. The gas-phase white carbon black was observed under a TEM electron microscope. The white carbon black particles are spherical particles. They do not exist as single particles. Many white carbon black particles are gathered together, and these aggregates agglomerate together to form bands. The structure of the voids forms a three-dimensional network structure after being dispersed and static in the base material. This three-dimensional network structure is a dynamic and temporary structure that will deform under the action of external force, and the shape and size of the void will also be The changes happened with it, which is very "kneadable". It can also be observed under the TEM electron microscope that the surface of the silica particles is full of micropores, which extend from the surface of the particles to the inside, but the micropores are very small and it is difficult for rubber molecules to enter.

In the infrared test of the gas-phase white carbon black, it can be found that there are a large number of silanol groups (SiOH) on the surface of the particles. There are two kinds of hydroxyl groups. One is an isolated free hydroxyl group, which is "connected" on the surface of the particle at a certain distance; The second is the continuous associative hydroxyl group that forms hydrogen bonds, which are combined with Si-O-Si in the interior of the particles. Due to the hydrogen bonding on the surface, the agglomerates formed are both developed and firm.