How to improve the tear strength of silicone rubber products?

The tear strength of silicone rubber is mainly affected by raw rubber, reinforcing agent and vulcanizing agent.

Raw rubber: High vinyl content and low vinyl content silicone rubber products used together. When the vinyl mole fraction of the composite glue is less than 0.15%, the tear resistance of the composite glue can be significantly improved by appropriate mix ratio. When 0.15% vinyl mole fraction of silicone rubber and 0.06% vinyl mole fraction of silicone rubber are used in 50/50 combination, the combined rubber has a vinyl mole fraction of 0.15%, and the tear strength is the highest, reaching 45.8kN /m. When the molar fraction of vinyl in the composite rubber was more than 0.15%, the combination ratio of silicone rubber had little effect on the tearing performance of vulcanized rubber.

Reinforcer: The most important factor affecting tear strength is the reinforcer system. The commonly used reinforcing agents include gaseous silica and precipitated silica, among which precipitated silica has the best reinforcing effect. According to the effect of silica particle size on the reinforcing effect, the smaller the particle size, the larger the specific surface area, the stronger the adsorption capacity of rubber molecules on the surface of silica black, and the better the reinforcing effect. According to this principle, as far as possible to choose smaller particle size of gaseous silica. Therefore, silica modification is also the main way to improve the tear strength of silicone rubber products.

Vulcanizing agent: silicone rubber products commonly used vulcanizing agent is peroxide, used for molding and extrusion. Take the Elkesilicone HCR 9170 UE as an example. After adding the first grade platinum vulcanizing agent, the tearing strength reaches 47.8kN/m, which is higher than that of peroxide vulcanization. Therefore, for high tear requirements of the product, you can consider the use of platinum vulcanizing agent.