Silicone rubber is one of the most important silicone products.
The raw materials for preparing silicone rubber are usually composed of linear polysiloxane [silicone rubber raw rubber, abbreviated as silicone raw rubber], reinforcing fillers, crosslinking agents, catalysts, modified additives, etc. All the raw materials can be processed into compound rubber through mixing (or blending). Under certain conditions, when mixed rubber is cross-linked and vulcanized, it can transform from a viscous liquid state to a highly elastic state - vulcanizate.
The chemical structure of raw rubber is similar to that of silicone oil, and its general formula is as follows:
In the general formula,R 'represents an alkyl or hydroxyl group, and R is usually a methyl group, but other groups such as ethyl, vinyl, phenyl, trifluoropropyl, etc. can also be introduced to improve and enhance certain properties. For instance, replacing a portion of the methyl groups with phenyl groups can enhance the flexibility and radiation resistance of silicone rubber at low temperatures. Introducing a small amount of vinyl can improve the vulcanization performance and compression set of silicone rubber.
The presence of trifluoropropyl groups can endow silicone rubber with excellent oil resistance. Silicone rubber containing cyano groups, like fluorosilicone rubber, can resist non-polar solvents. After introducing a certain amount of phenylene groups into the siloxane main chain of silicone rubber, the mechanical strength can be increased from 110MPa to 170-180MPa, and the heat resistance is also improved.
Therefore, depending on the different organic groups attached to the silicon atoms, silicone rubber can be classified into many varieties such as dimethyl silicone rubber, methyl vinyl silicone rubber, methyl phenyl silicone rubber, fluorosilicone rubber, nitrile silicone rubber, ethyl silicone rubber and phenylene silicone rubber.