4. Thiuram: The full name is tetramethylthiuram disulfide, and the trade name is TMTD. It is a widely used vulcanizing agent in wire and cable rubber, and can also be used as a vulcanization accelerator. The pure product has a melting point of 147°C to 148°C, a specific gravity of 1.29, and is an off-white powder. It is an ultra-speed accelerator for natural rubber, which can be decomposed to generate free radicals at 100 ° C, so it can be cross-linked. The use of thiuram as a vulcanizing agent can improve the heat resistance and aging resistance of rubber. The vulcanization curve is flat and not easy to burn. Suitable for natural rubber, styrene-butadiene rubber, nitrile rubber and all unsaturated rubbers containing double bonds. In general heat-resistant rubber, the dosage of thiuram is 2 to 3 parts, while the dosage of continuous vulcanization rubber formula is 2 to 5 parts, and the dosage of thiuram is 0.3 to 0.5 parts when used as an accelerator.
5. Peroxide Peroxide vulcanization refers to organic peroxides (such as peroxide mixed with propylene benzene, etc.) that emit free radicals when the vulcanization is added to the rubber compound. Peroxide ur makes carbon-carbon bonds cross-link between the 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. Because the strength and tear resistance of the obtained vulcanizate are poor, the industry is mostly used for the vulcanization of silicone rubber, ethylene rubber, butadiene rubber, and also for the co-vulcanization of some combined rubbers.
Commonly used peroxide vulcanizing agents are dialkyl peroxides, diacyl peroxides and peroxyesters, etc., which can vulcanize most rubbers. The selection of peroxides generally needs to be considered in terms of the half-life, volatility, odor, the influence of acid and alkali substances on it, the safety of processing, and the physical and mechanical properties of the vulcanizate. Wherein dialkyl peroxide is widely used, such as dicumyl peroxide (DCP) is suitable for 160X: vulcanization, and the price is cheap 'is a vulcanizing agent that is currently used most; 1,1-di-tert-butylperoxide Base-3,3,5-trimethylcyclohexane (3M), suitable for lower temperature vulcanization. The cross-linking efficiency of the oxide refers to the amount (mol) of 1 mol of the organic peroxide that chemically cross-links the molecules of the rubber product. If 1 mol of peroxide can generate 1 mol of rubber cross-linking bonds, the cross-linking efficiency is 1. Peroxide vulcanization is the homolysis of peroxides under the action of heat or radiation to generate free radicals, such as alkyl peroxides to generate two alkoxy radicals, diacyl peroxides to generate two acyloxy radicals, peroxyesters Then one alkoxy radical and one free radical are produced. During thermal crosslinking of rubber products, tertiary alkyl groups and tertiary oxygen groups may be further cleaved to generate alkyl radicals