Silicone rubber formulation classification and precautions

Different characteristics into the following categories:

    1 Universal : The vinyl silicone rubber composition and reinforcing agents , vulcanizing machine belongs moderate mechanical properties , tensile strength 4.9 ~ 6.9MPa (5 ~ 7kgl/cm2), elongation : 200 ~ 300% , is the maximum amount of versatility largest class of compound.

    2 High Strength ( high tear resistance ) : the use of phenyl vinyl silicone rubber or silicone rubber, low to high surface area carbon black or fumed silica after modification made ​​reinforcing agent , and adding a suitable and special additives, processing aids , such as integrated with the improvement measures to improve cross-linked structure ( produce concentrated crosslinked ) , improved tear strength.

    3 temperature type : the use of low- vinyl phenyl silicone rubber or silicone rubber, heat-resistant additives , and the type of reinforcing agents appropriately selected , it can be a high temperature silicone rubber of 300 ~ 350 ℃ .

    4 Low temperature : mainly low- phenyl silicone rubber, brittleness temperature up to -120 ℃, when you do not lose flexibility in -90 ℃.

    5 low compression type : vinyl silicone rubber used to make vinyl specific organic peroxide vulcanizing agent .

    Silicone rubber by vulcanization mechanism can be divided into three categories : organic peroxide initiators of radical crosslinking , polycondensation reaction type addition reaction type .

Silicone rubber formulation attention:

    A silicone rubber is saturation of raw rubber, usually without sulfur vulcanization , thermal curing, heat curing organic peroxide vulcanizing agent to do so , shall not contain raw rubber and peroxide decomposition products can play a role in the activity substances ( such as channel black , some organic accelerator and antioxidant , etc. ) , otherwise it will affect the cure .

    2 silicone products in general use at high temperatures , the blending agent should be stable at high temperatures , for inorganic oxide is usually used to make a reinforcing agent .

    3 silicone rubber in the role of trace amounts of acid and other chemical agents can lead to polar siloxane cleavage and rearrangement, resulting in reduced heat resistance of silicone rubber . Therefore, the choice must be considered with the agent when its acidity , peroxide cleavage product should also consider the pH to affect the performance of vulcanized rubber .

    HTV silicone rubber vulcanizing agent : mainly organic peroxides, aliphatic azo compounds , inorganic compounds, and other high-energy rays .