Effect of silane coupling agent in silicone rubber

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Silicone rubber is composed by silicon-oxygen bond（-Si-O-）which has a big bond energy and bond angle, so silicone rubber has a good heat resistance, superior uv resistance, excellent weather resistance and outstanding flexibility and low temperature resistance. Therefore, silicone rubber is widely used in aerospace, military, medical equipment, rail transit, construction, electronics, automobile, electrical insulation and many other fields.

In the application of silicone rubber, the silane coupling agent is very popular and useful. In the field of RTV, silane coupling agent is mainly used to improve the adhesive property of silicone rubber. While in the field of HTV, the surface of the packings is modified by the silane coupling agent, so as to improve the performance of all aspects of hot vulcanized rubber.

1、Mechanical property. The use of silane coupling agent can dramatically improve the tensile strength, tear strength and 300% modulus of the silicone rubber.

2、Sulfurization property. When added to the silicone rubber, first, the silane coupling agent play a role like physical plasticizer during silicone rubber’s mixing and can reduce the viscosity of silicone rubber by permeating and swelling.

3、Heat-conducting property. Silane coupling agent can greatly improve the performance of thermal conductivity of hot vulcanization silicone rubber, the oxygen groups react with hydroxyl groups on the surface of the thermal conductive filler, and the double bond and silicone rubber can form chemical bonds through crosslinking reaction, then the silane coupling agent may play a “bridging effect” role between the thermal conductive filler and silicone rubber. On the one hand, can improve the interfacial compatibility of the rubber and the filler, reduce the interface and other possible defects and reduce the thermal resistance of the system. On the other hand, the coupling agent can increase the thermal resistance and therefore improve the thermal conductivity of silicone rubber.

As the fast development of modern society, the silicon rubber will be used more and more widely in modern industry. One side, the functionalize silicon rubber need to be researched; the other side, the mechanical properties and processability must be guaranteed. Therefore, in order to remarkably improve the overall performance of silicon rubber, Silane coupling agent should be used as the “bridge” between the functional filler and silicone rubber to improve the compatibility and the dispersion of the filler in silicone rubber.