What does vulcanization primarily involve?

Vulcanization primarily involves the cross-linking of rubber molecules with sulfur, which enhances the material's elasticity, strength, and durability. This chemical process transforms raw rubber into a more resilient and heat-resistant material, suitable for various applications. By introducing sulfur atoms into the rubber’s molecular structure, it creates cross-links that bond the long chains of rubber together. This results in a significant improvement in the physical properties of rubber, making it ideal for products such as tires, gaskets, and seals.

The other options do not accurately capture the essence of vulcanization. For instance, heating rubber at low temperatures does not facilitate the necessary chemical reactions that cause cross-linking; rather, vulcanization typically requires higher temperatures. Cooling rubber may increase rigidity but does not involve the chemical transformation characteristic of vulcanization. Lastly, while moisture can affect rubber properties, its elimination is not a primary aspect of the vulcanization process and does not contribute to the significant improvements sought through this important chemical reaction.