Elemental composition of vulcanizing agent

The typical representative is sulfur, which is the most basic and important vulcanizing agent in the rubber industry. Using ordinary sulfur-accelerator-activator system, the obtained vulcanizing agent has the advantages of good comprehensive performance and low cost. Therefore, it still dominates in the rubber industry, especially in the tire industry. Insoluble sulfur can avoid sulfur spraying, is not easy to burn, and can be used for particularly important parts or products.

1, sulfur: The use of sulfur in the rubber industry has sulfur powder, insoluble sulfur, colloidal sulfur, precipitated sulfur, sublimated sulfur, acid sulfur, not crystalline sulfur. In 1839, Charles Goodyear, an American, mixed sulfur yellow with rubber and heated the material with good performance. This milestone discovery prompted people to start in-depth research on the reaction mechanism, reaction heat history and reaction kinetics of sulfur yellow vulcanized rubber. After more than 100 years of development, Lautenschlaeger et al. used 2-methyl-2-pentene to simulate the vulcanization of natural rubber in 1979, and finally determined the terminal structure of the crosslinking bond, the external network structure and the main chain isomerization reaction product. As a rubber vulcanizing agent, the development of sulfur after hundreds of years. Compared with other kinds, the low price of sulfur, the formation of vulcanizing rubber comprehensive performance is better, so it is still the leading vulcanizing agent of the international rubber industry, accounting for about dozens of organic and inorganic vulcanizing agent of the total composition of 85%. In order to meet the needs of rubber development, new products of sulfur are constantly emerging, such as the S80 GA F500 (yellow granular product) produced by MLPC International in France, which is the pre-dispersion of sulfur in acrylic derivative elastomers, with 80% sulfur content. The product has no dust and does not pollute the environment. Non-stick at room temperature, easier to feed and weigh.

Insoluble sulfur: ordinary sulfur vulcanized rubber is easy to spray frost when parked, and has a tendency to burn, which greatly affects the performance of the final product. In order to make up for the deficiency of Sulfur, research on sulfur modification has been started. A successful example IS polymer sulfur or Insoluble Sulfur (IS), which is a linear polymer sulfur insoluble in carbon disulfide and a μ-type of sulfur. The average molecular weight of sulfur in this polymerized state is very high, and it is widely believed to be 30,000 to 40,000 molecular weight after continuous testing. Insoluble sulfur is usually divided into oil-filled and unfilled types when used, and the vast majority (*99%) used in industry are oil-filled types. Compared with common sulfur, insoluble sulfur has the following advantages :(1) the adhesive will not appear in the storage period of spray; (2) there is no migration phenomenon in the compound (especially in butadiene rubber and butyl rubber compound); (3) can reduce the coking phenomenon in the process of mixing and storage; (4) conducive to the adhesion of rubber and other materials; (5) can shorten the curing time, reduce the amount of sulfur.

2, selenium, tellurium: for natural rubber and styrene butadiene rubber second vulcanizing agent, single use can not vulcanize.