Principle of rubber vulcanization

‌ Rubber vulcanization is a process by which rubber is converted from a plastic and viscous compound to an elastic or hard rubber product by chemical or physical factors. During the vulcanization process, the sulfur bonds between the rubber molecular chains are broken, allowing the rubber molecular chains to move freely, thus changing their physical and chemical properties. This process is usually carried out under high temperature and pressure, by adding crosslinking additives such as ‌ vulcanization agent and ‌ accelerator, the linear macromolecules are transformed into three-dimensional network structure. Vulcanization not only improves the properties of rubber, such as strength and temperature sensitivity, but also makes rubber products have better dimensional stability and physical and mechanical properties. ‌ 

Rubber vulcanization can be achieved by a variety of methods, including the use of vulcanizing agents and accelerators under certain temperature and pressure conditions, or through the action of physical factors such as ‌ gamma rays. In the vulcanization process, the chemical reaction between raw rubber and vulcanizing agent or raw rubber and raw rubber occurs, and the linear rubber macromolecules are cross-linked into three-dimensional network structure macromolecules, so as to realize the vulcanization of rubber. ‌ 

The causes of bubbles in rubber vulcanization may include: uneven distribution of vulcanizing agent, improper control of vulcanization temperature, insufficient vulcanization time and other factors. These problems can lead to incomplete vulcanization, resulting in bubbles during the vulcanization process.

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Rubber vulcanization classification mainly includes cold vulcanization, ‌ room temperature vulcanization and hot vulcanization three categories. ‌

Cold vulcanization is a vulcanization process at a lower temperature, ‌ the advantage of this method is that it can be carried out without heating, ‌ suitable for temperature-sensitive rubber materials. ‌
Room temperature vulcanization refers to vulcanization at room temperature, ‌ this method does not require additional heat source, ‌ suitable for those rubber materials that can vulcanize themselves at room temperature. ‌
Thermal vulcanization is the vulcanization process at a higher temperature, ‌ this method is suitable for most rubber materials, ‌ by heating to accelerate the vulcanization reaction, ‌ makes the rubber quickly reach the required physical and mechanical properties. ‌
In addition, ‌ rubber vulcanization also involves different vulcanization systems, ‌ including sulfur vulcanization system, ‌ metal oxide vulcanization system, ‌ peroxide vulcanization system, ‌ resin vulcanization system, ‌ quinone oxime vulcanization system and polyamine vulcanization system. ‌ The choice of these vulcanization systems depends on the type of rubber and the needs of the application