Vulcanization is a process that involves heating rubber with sulfur and other chemicals to change its physical properties. The following changes are observed in rubber when it is vulcanized:

• Increased hardness: Vulcanized rubber is harder than non-vulcanized rubber, which increases its tensile strength and reduces the risk of physical damage.

• Improved elasticity: Vulcanized rubber is more extensible than crystalline solids, and it contracts when heated and gives up heat when stretched.

• Retains original shape: Vulcanization forces rubber to retract, but it retains its original shape.

• Resistance to deformation: Vulcanized rubber is less vulnerable to deformation than non-vulcanized rubber.

• Improved tear, aging, and ozone resistance: Radiation vulcanization improves the tearing, aging, and ozone resistance properties of rubber.

Vulcanization links polymer chains to one another covalently, which results in the formation of a rigid solid that does not flow over time. Vulcanized rubber contains polymer chains that are "locked" into place, which makes it useful for the production of tires that are expected to withstand high temperatures and degradation over time without deforming.