Natural and synthetic rubbers are made harder and stronger by the process of

Explanation

Vulcanization involves heating rubber with sulfur to create chemical cross-links between polymer chains. These cross-links make rubber tougher, more elastic, and heat-resistant.

Raw rubber is sticky and weak, but vulcanized rubber is durable and maintains its shape. Car tires, rubber bands, and shoe soles all use vulcanized rubber.

The sulfur atoms form bridges between polymer chains, preventing them from sliding past each other easily. This cross-linking transforms soft rubber into a strong, useful material.