Dimethyl silicone rubber is the earliest silicone rubber put into commercial production, which can maintain good elasticity in the range of -60 ~ 200℃, good aging resistance, excellent electrical insulation, moisture-proof, shock-proof and physiological inertia.
Dimethyl silicone rubber is mainly used for coating strong materials, and can also be made into various extruded calendered products, which are used in electromechanical, aviation, automobile, medical and other industries. However, dimethyl silicone rubber was replaced by methyl vinyl silicone rubber because of its low vulcanization activity, difficult vulcanization, easy foaming of the inner layer and large permanent deformation under high temperature compression.
Two. silicone gasket
Because introducing a small amount of vinyl into the macromolecular structure of silicone rubber can greatly improve the vulcanization performance of silicone rubber, most of the silicone rubber used at present contains vinyl. Methyl vinyl silicone rubber is the most common type of silicone rubber, which is currently dominant in the production of silicone rubber at home and abroad. Because it introduces partially unsaturated vinyl groups into the side chain, its processability and physical and mechanical properties are better than those of double-base silicone rubber. Besides the general characteristics of dimethyl silicone rubber, it also has a wide application temperature range and can maintain good elasticity in the range of 60-260℃. It is easier to vulcanize than dimethyl silicone rubber, and has small compression set, good solvent swelling resistance, high pressure steam stability and excellent cold resistance. Moreover, due to the use of peroxide with low activity for vulcanization, the shortcomings of bubble generation and poor rubber stability during vulcanization are reduced. Therefore, methyl vinyl silicone rubber can generally be used to make products with large thickness. Methyl vinyl silicone rubber is the most widely used silicone rubber. In recent years, various kinds of high-performance and special-purpose silicone rubber have emerged, mostly vinyl silicone rubber, such as high-strength silicone rubber, low-compression permanent deformation silicone rubber, post-vulcanized silicone rubber, heat-resistant conductive silicone rubber, medical silicone rubber and so on. Methyl vinyl silicone rubber is widely used as a protective layer for gaskets, sealing materials and fragile shock-proof parts in aviation industry. In the electrical industry, it can be used as advanced insulating materials such as electronic components, dynamic sealing rings of high-temperature potentiometers and sealing rings of underground long-distance communication equipment; In medicine, methyl vinyl silicone rubber is used in plastic surgery, artificial heart valves, blood vessels and so on. Because it has little physiological reaction to human body and is non-toxic.