Fluorosilicone rubber is a type of silicone rubber with a fluoroalkyl group introduced into the side chain. Commonly used fluorosilicone rubbers are fluorosilicone rubbers containing methyl, trifluoropropyl and vinyl groups.
Fluorosilicone has good heat resistance and excellent oil and solvent resistance, such as aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, various petroleum-based fuel oils, lubricating oils, hydraulic oils and some synthetic oils at room temperature. The stability at high temperature is better, which is beyond the pure silicone rubber. Fluorosilicone rubber has good low temperature performance, which is a great improvement for pure fluororubber. The temperature range of fluorosilicone rubber containing trifluoropropyl group to maintain elasticity is generally -50 ℃ ~ +200 ℃, and its high and low temperature resistance is worse than that of vinyl silicone rubber, and toxic gas will be generated when heated to above 300 ℃. It is much worse than vinyl silicone rubber in terms of electrical insulating properties. Adding an appropriate amount of low-viscosity hydroxy fluorosilicone oil to the fluorosilicone rubber compound, heat treatment of the compound, and then adding a small amount of vinyl silicone rubber can significantly improve the process performance, which is beneficial to solve the problems of sticky rollers and serious storage structure. , can prolong the effective service life of the rubber compound. When the methylphenylsiloxane chain segment is introduced into the above-mentioned fluorosilicone rubber, it will contribute to the improvement of low temperature resistance, and the processing performance is good.
Nitrile silicone rubber is a type of silicone rubber in which a nitrile alkyl group (usually β-nitrile ethyl or γ-nitrile propyl) is introduced into the side chain. The introduction of polar nitrile groups improves the oil resistance and durable solvent properties of silicone rubber, but its heat resistance, electrical insulation and processability are reduced.
The type and content of nitrile alkyl groups have a great influence on the properties of nitrile silicone rubber. For example, silicone rubber containing 7.5% γ-nitrile propyl group has similar cold resistance to low phenyl silicone rubber, and lower oil resistance than benzene. Base silicone rubber is better. When the content of γ-nitrile propyl group increases to 33~50% molar, the cold resistance is significantly reduced, the oil resistance is improved, and the heat resistance is 200 ℃. If β-nitrile ethyl is used instead of γ-nitrile propyl, the heat resistance of nitrile silicone rubber can be further improved.