Silicone rubber refers to a rubber whose main chain is composed of silicon and oxygen atoms alternately, and two organic groups are usually connected to the silicon atom. Ordinary silicone rubber is mainly composed of silicone chains containing methyl groups and a small amount of vinyl groups. The introduction of phenyl can improve the high and low temperature resistance of silicone rubber, and the introduction of trifluoropropyl and cyano groups can improve the temperature and oil resistance of silicone rubber.
(1) High temperature performance. The remarkable feature of silicone rubber is its high-temperature stability. Although the strength of silicone rubber is only half that of natural rubber or some synthetic rubber at room temperature, it can still maintain a certain degree of flexibility and resilience in high-temperature environments above 200 ° C. Elasticity and surface hardness without significant changes in mechanical properties.
(2) Low temperature performance The glass transition temperature of silicone rubber is generally -70 ~ -50 ° C, and the special formula can reach -100 ° C, indicating its excellent low temperature performance. This is of great significance to the aviation and aerospace industries.
(3) The Si-O-Si bond in the weather-resistant silicone rubber is very stable to oxygen, ozone and ultraviolet rays, and has excellent weather resistance without adding any additives.
(4) Electrical performance. Silicone rubber has excellent insulation properties, as well as corona resistance and arc resistance.
(5) Physical and mechanical properties. At room temperature, the physical and mechanical properties of silicone rubber are worse than those of general-purpose rubber, but its physical and mechanical properties are better than those of general-purpose rubber at a high temperature of 150 ° C and a low temperature of -50 ° C.
(6) Oil and chemical resistance. Ordinary silicone rubber has medium oil and solvent resistance.
(7) Gas permeability. At room temperature, the air permeability of silicone rubber to air, nitrogen, oxygen, carbon dioxide and other gases is 30-50 times higher than that of natural rubber.
(8) Physiological inertia. Silicone rubber is non-toxic, odorless, odorless, non-adhesive to human tissues, has anticoagulant effects, and has very little reactivity to body tissues. Particularly suitable as a medical material.
Silicone rubber is divided into thermal vulcanization type (high temperature vulcanized silica gel HTV) and room temperature vulcanization type (RTV). Among them, room temperature vulcanization type is divided into polycondensation reaction type and addition reaction type. High temperature silicone rubber is mainly used to make various silicone rubber products, while room temperature silicone rubber is mainly used as an adhesive, potting material or mold.
(1) Construction industry. Used for the bonding of glass and metal curtain walls, roof encapsulation, door and window sealing, various pools and ceramic tiles. (2) Electronics industry. Encapsulation and potting materials for electronic and electrical components, which are resistant to moisture, shock and shock, resistance to sudden changes in temperature and corrosion of chemicals. (3) Mold. The excellent simulation and good demolding properties of silicone rubber make it widely used in the soft mold industry. (4) Automobiles, ships and aviation. Used as in-situ molded gaskets, window seals, and anti-corona for electronic and electrical connectors.