Vulcanization is a process in which raw rubber is heated with sulfur or dichlorodimethyl ether to improve its mechanical properties. During this process, catalysts such as 2-mercaptobenzothiazole or tetramethylthiuram disulfide are used to accelerate the reaction. Typically, 1.8% to 2.5% sulfur is used, and the processing temperature should be between 120 °C and 160 °C.
Sulfur forms cross-links between rubber molecules, giving the material elasticity. After vulcanization, rubber loses its plastic-like characteristics and becomes more flexible and durable. The rubber produced through this process becomes more resistant to cracking and demonstrates strong durability under adverse weather conditions.
Over time, sulfur bridges give way to oxygen bridges, causing visible changes in the rubber surface. In addition to the classic sulfur bridge method, alternative methods such as peroxides and metal oxides are also used in vulcanization. Metal oxides are particularly preferred in some synthetic materials, such as chloroprene rubber.
In the vulcanization of chloroprene rubber, metal oxides such as MgO, ZnO, and sometimes PbO are used. These substances influence the ambient temperature during the process and help the rubber molecules form cross-links. Since conventional accelerators may cause issues during curing, alternatives such as ETU (ethylene thiourea) are used. However, because ETU can have adverse effects on human health, rubber manufacturers in Europe are conducting research projects to find safer alternatives.
Conclusion
Vulcanization is a critical process for enhancing the durability and elasticity of rubber products. This process is optimized using both traditional and alternative methods to ensure compliance with health and safety standards.
