Silicone rubber refers to the rubber whose main chain is composed of silicon and oxygen atoms alternately, and the silicon atoms are usually connected with two organic groups. Common silicone rubber is mainly composed of silicone chain links containing methyl and a small amount of vinyl. The introduction of phenyl can improve the high and low temperature resistance of silicone rubber, while the introduction of trifluoropropyl and cyano can improve the temperature resistance and oil resistance of silicone rubber. Silicone rubber has good low temperature resistance and can work at - 55 ℃ generally. After introducing phenyl, it can reach - 73 ℃. The heat resistance of silicone rubber is also very outstanding. It can work for a long time at 180 ℃. It can withstand elasticity for several weeks or more even at a temperature slightly higher than 200 ℃. It can withstand a high temperature of more than 300 ℃ instantaneously. Silicone rubber has good air permeability, and the oxygen permeability is the highest among synthetic polymers. In addition, silicone rubber is also physiologically inert and will not cause coagulation, so it is widely used in the medical field.

Classification
Silicone rubber can be divided into heat vulcanization type (high-temperature vulcanized silica gel HTV) and room temperature vulcanization type (RTV) according to its different vulcanization mechanism, in which the room temperature vulcanization type is divided into condensation reaction type and addition reaction type. High temperature silicone rubber is mainly used to manufacture various silicone rubber products, while room temperature silicone rubber is mainly used as adhesives, potting materials or molds. The amount of thermal vulcanization type is the largest. The thermal vulcanization type is divided into methyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ, the amount and product brand are the largest), methyl vinyl phenyl silicone rubber PVMQ (low temperature resistance and radiation resistance), and other silicone rubber, fluorosilicone rubber, etc.

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