High temperature vulcanized silicone rubber sealing strip is a kind of sealing strip made of a new material. It is mainly based on methyl vinyl raw rubber, with reinforcing filler, wetting agent (structure control agent), other additives, crosslinking agent and color masterbatch added to prepare a rubber mixture, which is extruded by a rubber extruder and vulcanized by a high temperature drying channel. The production process is shown in Figure 1. Raw rubber: polymerization degree is 5000-8000, vinyl content is 0.03% - 0.3%; filler: fumed silica, precipitated silica, diatomite, quartz powder, etc.; structure control agent: hydroxy silicone oil, silazane, diphenylsiliol, etc; The Si-O bond energy of the main chain of methyl vinyl siloxane is 444kj / mol, which is larger than the C-C bond energy (356kj / mol) and C-O bond energy (339kj / mol) of the main chain of ordinary organic polymer, making the high temperature vulcanized silicone rubber sealing strip have better aging resistance, high resilience, high and low temperature resistance and other excellent properties than the traditional sealing strips.

Figure 1 production process of silicone rubber sealing strip

Reaction mechanism of high temperature vulcanized silicone rubber

The crosslinking reaction of high temperature vulcanized silicone rubber can be divided into peroxide initiated reaction and hydrosilylation reaction according to the type of crosslinking agent. The peroxide initiated reaction is that the organic peroxides decompose to produce free radicals, which attack the methyl or vinyl groups on the siloxane side to cause chain reaction and cross-linking. 

Hydrosilylation is the crosslinking reaction of vinyl and hydrosilide on the side group of siloxane under the catalysis of platinum complex.