Silicone rubber refers to a rubber whose main chain is composed of alternating silicon and oxygen atoms, and usually has two organic groups attached to the silicon atom. Ordinary silicone rubber is mainly composed of a silicone chain containing a methyl group and a small amount of a vinyl group. The introduction of phenyl can improve the high and low temperature resistance of silicone rubber, and 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 generally works at -55 °C. After the introduction of the phenyl group, it can reach -73 °C. The heat resistance of silicone rubber is also outstanding. It can work for a long time at 180 °C. It can withstand elasticity for several weeks or more at a temperature slightly above 200 °C, and can withstand high temperatures above 300 °C instantaneously. Silicone rubber has good gas permeability and the highest oxygen transmission rate among synthetic polymers. In addition, silicone rubber is also physiologically inert and does not cause prominent characteristics of blood coagulation, and thus is widely used in the medical field.
Silicone rubber is classified into a heat-curing type (high-temperature vulcanized silica gel HTV) and a room temperature vulcanized type (RTV), wherein the room temperature vulcanization type is further divided into a polycondensation type and an addition type. High-temperature silicone rubber is mainly used to manufacture various silicone rubber products, while room temperature silicone rubber is mainly used as a bonding agent, potting material or mold. The hot vulcanization type is the largest, and the hot vulcanization type is divided into methyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ, the most used and product grade), methyl vinyl phenyl silicone rubber PVMQ (low temperature resistance, radiation resistance) ), other silicone rubber, fluorosilicone rubber, etc.