Event Details

  • Vulcanization accelerator
    Vulcanization accelerator is a kind of auxiliary agent that can accelerate the vulcanization reaction speed, shorten the vulcanization time, lower the vulcanization temperature, reduce the amount of vulcanizing agent, and can improve or improve the physical and mechanical properties of vulcanizates. It is usually used in salt bath curing lines. According to its nature and chemical composition, it can be divided into two categories: inorganic accelerators and organic accelerators. Inorganic accelerators were used the earliest, but due to the small promotion effect, the performance of vulcanizates was poor. Basically replaced by organic accelerators. With the continuous development of the varieties and uses of synthetic rubber, the names of existing accelerators are complex. According to the chemical structure of the accelerators, they are usually divided into thiazoles, thiurams, sulfenamides, guanidines, and dithiocarbamic acids. Salts, aldehydes, xanthates and thioureas. Traditional accelerators containing secondary amine groups, such as NOBS, DIBS, TNTD, and TETD, are considered to have potential health hazards. Therefore, the search for alternatives to these accelerators or the development of nitrosamine-free accelerators has received widespread international attention. The new accelerator N-tert-butyl-2-bisbenzothiazole sulfenamide introduced by the United States company is the best substitute for traditional accelerators containing secondary amine groups.

    Peroxide vulcanization
    The vulcanization systems used in the industry are mainly peroxides (2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, DCP, etc.). The vulcanization mechanism is mainly divided into: (1) The peroxide decomposes into two active radicals; (2) the generated active radicals attack the active hydrogen atoms or unsaturated double bonds on the rubber chain; (3) the two active rubber chains collide to form a crosslinked network. The degree of vulcanization of rubber is related to the degree and rate of decomposition of peroxides. Chatterjee et al. Compared three different DCP, 3,3,5,7,7-pentamethyl-1,2,4-triepoxyhexane (PMTO) and cumyl hydrogen peroxide (CHP) with different half lives. The effect of oxide vulcanizing agents on the mechanical properties of PDMS / PA12 thermoplastic vulcanizates. The results show that PMTO is the best vulcanizing agent when the processing temperature is 190 ℃. This is mainly because PMTO has a long half-life and can fully vulcanize the silicone rubber to obtain a thermoplastic vulcanizate with a high degree of vulcanization. For peroxides with a short half-life, the vulcanization rate is too fast, which is likely to cause local vulcanization. The silicone rubber cannot be fully vulcanized, which affects the product performance. Mani et al. Found that in the dynamic vulcanization process of PDMS / PA12 thermoplastic elastomers with DCP as the vulcanizing agent, the addition of tetramethylpiperidine oxygen (TEMPO) can prolong the vulcanization time, so that the silicone rubber is fully vulcanized and uniformly dispersed in PA12. In this process, TEMPO actually acts as a polymerization inhibitor, which is mainly to generate a graft copolymer with the generated active radicals of the polymer to prevent collisions between the active radicals of the polymer to generate a network structure.

  • 12/17/19 at 1:00 AM -
    12/31/20 at 1:00 AM
  • Where
    Derby, DE23 Map
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