What is Vulcanization?

Vulcanization is a process that transforms rubber from a sticky substance to one that is smooth, durable, does not melt when heated, and does not adhere to metal. These useful characteristics are obtained by changing the chemistry of the rubber. In natural rubber, the rubber molecules move mostly independently of one another. This lack of structure accounts for natural rubber's liquid-like state. Vulcanization is a process that attaches these different molecules with sulfur chains, creating structure and as a result a more solid and durable material.

            Sulfur is special because it, along with carbon and silicon, can form chains composed of its own atoms. These chains will act as the ropes that tie the natural rubber molecules together. In the natural rubber molecule, there are several sites attractive to sulfur molecules. These sights are called curing sights. In these cure sites, a sulfur atom attaches. This sulfur atom forms a chain until it reaches another curing site, where the other side attaches. These connecting chains are called Sulfur Bridges (See Figure 1). Sulfur Bridges are from 2-10 atoms long.