Silica gel alias: silicone rubber is a kind of highly active adsorption material, is an amorphous substance, its chemical formula is MSiO2 • NH2O. Insoluble in water and any solvent, non-toxic and tasteless, stable chemical properties, in addition to strong alkali, hydrofluoric acid does not react with any substances.

Silica gel according to its properties and components can be divided into organic silica gel and inorganic silica gel two categories.
Organic silica gel is a kind of organic silicon compound, refers to contain Si-C bond, and at least one organic group is directly connected with the silicon atoms of the compound, the habit is also often those through oxygen, sulfur, nitrogen and so on the organic base and silicon atoms connected to the compound as organic silicon compound. Among them, polysiloxane, which is composed of -Si-O-Si- bond as skeleton, is a kind of organosilicate compounds with the largest number, the deepest research and the most widely used, accounting for more than 90% of the total amount. A class used for encapsulation.
The basic structural unit of organic silica gel products is composed of silicon - oxygen chain, side chain is connected with various other organic groups through silicon atoms. Therefore, in the structure of organosilicone products contain both "organic groups" and "inorganic structure", this special composition and molecular structure makes it set the characteristics of organic matter and inorganic function in a body.
Silicone rubber is mainly divided into room temperature vulcanized silicone rubber, high temperature vulcanized silicone rubber, silicone rubber by silicon and oxygen atoms to form the main chain, side chain for containing carbon groups, the maximum amount of side chain is silicone rubber for ethylene. Both heat resistance, and cold resistance, the use of temperature between 100--300℃, it has excellent weather resistance and ozone resistance to use good insulation. Disadvantages are low strength, poor tear resistance, wear resistance is also poor.