Vulcanization history
According to the analysis of the vulcanization history, there are four stages, i.e. scorch stage, hot vulcanization stage, flat vulcanization stage and over vulcanization stage.

Performance changes in the rubber vulcanization process

Changes in physical properties
During the vulcanization process, the physical and mechanical properties of rubber change significantly, so in the production process, changes in physical properties are often used to measure the degree of vulcanization. Different structures of rubber, in the vulcanization process, although the physical and mechanical properties of the changes have different tendencies, but most of the changes in performance is basically the same. For rubber with side vinyl structure, such as styrene-butadiene rubber, nitrile rubber, etc., there are similar changes in the vulcanization process, only in a longer period of time, the changes in various properties are more flat, the curve appears very large or very small value is not very obvious.

1, soluble vulcanization process will make the rubber soluble in the solvent ability gradually reduced, and can only be swollen; vulcanization to a certain time, the minimum value of swelling, continue to vulcanize and the tendency to gradually increase the swelling.

2, thermal stability vulcanization to improve the thermal stability of rubber, that is, the physical and mechanical properties of rubber with the degree of temperature change is reduced, vulcanization greatly improve the use of natural rubber temperature range for.

3, density and gas permeability in a certain range of vulcanization time, with the increase in crosslink density, rubber density has increased, and gas permeability with the increase in crosslink density and decline. This is due to the thermal movement of the macromolecular chain segments is caused by certain restrictions.

Chemical property changes
During the vulcanization process, the active functional groups or double bonds in the macromolecular structure of rubber are gradually reduced due to cross-linking, thus increasing the chemical stability.

Although rubber has many excellent properties, but raw rubber itself still has many shortcomings, the use of raw rubber alone can not be made to meet the requirements of various uses of rubber products. A variety of rubber must be added to the appropriate amount of the relevant matching agent, in order to make a practical value of rubber products. Also because of the addition of the matching agent can improve the performance of rubber, so that it meets the corresponding requirements for the use of rubber products to reduce the cost of rubber products.