Mechanism of action of accelerant

2022-05-30 11:59

In the vulcanization process, the organic vulcanization accelerator can make the vulcanization reaction of rubber change greatly. Rubber accelerator in the presence of vulcanization accelerator, reducing the sulfur ring fracture activation energy, as a result of the promoter itself cracking, increases the system of the concentration of the active center (free radicals or ion), accelerated the cause of sulfide chain reaction and chain extension reaction, improves the vulcanization reaction speed, at the same time, also improved the structure and properties of vulcanized rubber.

Rubber accelerator

The vulcanization reaction in the presence of the accelerator may be of the free radical type or ion type, or both, depending on the type of the accelerator, the vulcanization conditions, and the type of rubber. The mechanism of several commonly used organic vulcanization promoters is discussed

(a) the mechanism of action of thiazole accelerator

Rubber industry, the current use of benzothiazole group accelerator has two categories, that is, thiazole accelerator and late effect of sub-sulfonamide accelerator. Thiazole accelerator involved in the vulcanization reaction is considered to be the reaction process of free radicals, at the vulcanization temperature, accelerator cracking free radicals, caused and involved in a series of vulcanization reactions.

Thiol benzothiazole can be reduced by itself during the vulcanization process, which consumes the peroxide when it is present in the system. So there should be the following reaction:

1, mercaptan benzothiazole (accelerator M) to promote vulcanization

The above reaction shows that the accelerator M can decompose free radicals. When the sulfurization system contains elemental sulfur, there are the following reactions under the sulfurization conditions:

In the above formula, MSH represents mercaptan benzothiazole, double MS· represents benzothiazole radical, and MSxH represents polymercaptan benzothiazole, which is unstable. HS· and S9- X · radicals produced by the above reaction process can cause chain initiation and chain growth of sulfur sulfidation.