Peroxide vulcanization refers to organic peroxides that release free radicals when vulcanization and heating are added to the rubber ingredients (such as peroxide propylene and so on). Peroxide ur causes carbon-carbon bond cross-linking in rubber polymer chains. This type of peroxide can vulcanize most rubbers (except J-based rubber, neoprene, etc.) and is an important non-sulfur vulcanization system. The strength and tear resistance of the obtained vulcanizate are poor. In the industry, less vulcanization of silicone rubber, ethylene rubber and butyl rubber is used, and it is also used as co-vulcanization of some combined rubbers. Common peroxide curing agents are dialkyl peroxides, dioctyl peroxides, and peroxyesters, which can vulcanize most rubbers. The selection of peroxides generally requires consideration of the peroxide's half-life, volatility, odor, influence of acid and alkaline substances on it, processing safety, and physical and mechanical properties of vulcanizates. Among them, difluorenyl peroxide has been widely used. For example, dicumyl peroxide (DCP) is suitable for 160X: vulcanization and cheap. It is currently the most used vulcanizing agent; 1,1-di-tert-butyl peroxide 3,3,5-trimethylcyclohexane (3M), suitable for lower temperature vulcanization. The cross-linking efficiency of an oxide refers to the amount (mol) of 1 mol of organic peroxide that chemically cross-links rubber molecules. If 1 mol of peroxide can produce 1 mol of rubber cross-linking bond, the cross-linking efficiency is 1.
Peroxide vulcanization is the generation of free radicals by peroxides under the action of heat or radiation. For example, alkyl peroxides generate two alkoxy radicals, diacyl peroxides generate two acyloxy radicals, and peroxy esters. An alkoxy radical and a free radical are generated. During the thermal crosslinking process of rubber products, tertiary alkyl groups and tertiary oxy groups may be further cracked to generate alkyl radicals.