Who discovered the phenomenon of vulcanization of rubber, not everyone knows. Although the name of this person is often mentioned in advertising messages. His name was Charles Nelson Goodyear, and today his name is "worn" by well-known brand tires. Without his participation, “Indian rubber” (rubber) would probably never have been widely used, since it was just a curiosity, once brought from America. For many years, Charles conducted numerous experiments on mixing rubber with various components (from turpentine to toxic zinc oxide), until in 1839 he discovered the composition of this substance with sulfur.
What is a rubber vulcanization process ? From the point of view of chemistry, this is a combination of flexible rubber molecules into a three-dimensional grid of a spatial form, while transverse chemical bonds are quite rare. The latter property allows the rubber to remain as highly elastic as the natural rubber of which it is made.
When vulcanizing rubber, the mesh can be obtained under the influence of high temperature or radiation, as well as using a special chemical agent. As a rule, for the operation, special units are used, such as boilers, injection machines, presses, autoclaves, formators, vulcanizers and coolants (from hot steam to electric heating).
The vulcanization temperature of crude rubber can be quite diverse depending on how the final product is used. The classic range is from 130 to 200 degrees Celsius, although rubber coatings and sealants are sometimes vulcanized at room temperature (at 20 degrees, “cold vulcanization”). Agent substances for this process are quite diverse. Most often, sulfuric vulcanization is carried out, which allows you to get diene rubbers used in the manufacture of tires and rubber shoes. In addition, the so-called “accelerators” (for the latter type of process) play an important role, these are mainly sulfonamides and substituted tizols.
Hot vulcanization of rubber can be carried out in a very short period of time if accelerators are involved in the chemical process: dithiocarbamates or xanthates. In this case, the operation is fast at a temperature of about 110-125 degrees. For the vulcanization of some adhesives and latex mixtures when using sodium dimethyldithiocarbamate, lower temperatures (from 20 to 100 degrees) can be used.
Additional substances used during vulcanization of rubber (oligoester acrylates, peroxides, phenol-formaldehyde resins, etc.) make it possible to obtain products with high heat resistance, monolithicity, and improved dielectric properties. Also not the least role in the formation of a product (from the sole for boots to jewelry) is played by antioxidants (increase the service life of rubber) and plasticizers, which allow to reduce the viscosity of the substance during processing and the speed of "erasure".