Appearance of silicone rubber foam materials


The main chain of organosilicon materials contains "silicon oxygen silicon" structure, and the side chain contains a small amount of organic groups. Therefore, organosilicon materials have the dual advantages of organic and inorganic materials, such as high and low temperature resistance, radiation resistance, weatherability (no chemical bond, not easy to be decomposed by ultraviolet light and ozone), hydrophobicity, flame retardancy, physiological inertia, oil resistance and solvent resistance, which are unmatched by other materials, Silicone rubber foam (also called silicone rubber foam / foam silicone rubber) is a porous, low-density, compressible polymer elastomer material, which is made of silicone rubber, filler, vulcanizing agent and foaming agent. It is widely used in silicone rubber and foam materials. It not only has high elasticity of rubber, but also has the properties of sound absorption and shock absorption of foam. It is mainly used for cushioning pad, gasket, sound insulation material, insulating material, aviation heat insulation material and other high performance materials.


Excellent properties of silicone rubber


Silicone rubber has many excellent properties: (1) high and low temperature resistance. Silicone rubber has excellent mechanical properties at high temperature (above 200 ℃), but still has certain toughness and elasticity. The glass transition temperature can be as low as - 70 ℃. The working temperature of silicone rubber is generally - 100 ℃ to 350 ℃. It can withstand thousands of degrees of instantaneous high temperature, so it is often used to make heat-resistant coatings, such as aviation, (2) In addition, silicone rubber is not easy to burn in the process of arc discharge because there are few carbon atoms in its structure, and its reinforcing filler silica is suitable for high voltage applications. (3) the surface of physiological inertia silicone rubber is hydrophobic, so the physical properties of silicone rubber decrease very little in humid environment, Poor adhesion, can play a role in isolation.


Characteristics of silicone rubber


But it is harmless and tasteless. It is harmless to human health. It can only react with the body slightly. This makes it very excellent in physiological inertia, and is also very advantageous in physiological aging properties. Silicone rubber foam is widely used because it has excellent properties of silicone rubber and foam material, not only has high resilience and aging resistance of rubber, It also has the properties of sound absorption and shock absorption of foam. It is mainly used for waterproof, shock absorbing, sealing gaskets (sealing grade IP68), sound insulation, heat insulation, aviation insulation and other high performance requirements. According to the structure of foam holes, silicone rubber foam can be divided into closed, open and mixed type, and closed cell foam silicone foam has good characteristics of shock absorption, sound insulation, heat insulation, flame retardancy and explosion protection.


Introduction of silicone rubber


(1) the density of silicone rubber is chosen as the density of silicone rubber. The density of silicone rubber is 1.17g/cm3. But by foaming treatment, the density of silicone rubber foam prepared by the current ripening process can be as low as 0.16-0.20 g/cm3, which can be used for car seat and headrest parts. The traditional silicone rubber foam (density of 0.45 g / cubic centimeter) is widely used for gap filling in sealing and shock absorption, (2) the flame-retardant oxygen index of foam silica (oxy). index:OI ）It refers to the minimum oxygen concentration required for flame combustion of substances in the oxygen nitrogen mixture gas flow under specified conditions, which is one of the indexes to judge the flame retardancy of polymers, General: oxygen index < 22 is flammable material; 22 < oxygen index < 27 is combustible; The oxygen index > 27 is a flame retardant material. (3) the electrical insulation performance of silicone foam increases as the amount of physical filler increases. The volume resistivity and surface resistivity of silicone rubber decrease, and the dielectric constant and dielectric loss factor increase. It can be seen that adding physical fillers can damage the electrical insulation properties of silicone rubber.