Tyre technology — meaning of vulcanization In automotive service, the term ‘‘vulcanizing’’ rubber generally means which process?

Introduction / Context:
Vulcanization transforms raw, sticky rubber into a durable elastomer suitable for tyres, belts, and seals. The process dramatically improves mechanical and thermal properties.

Given Data / Assumptions:

• Automotive rubber components (tyres, tubes, patches).
• Conventional sulphur-based vulcanization chemistry.
• Heat and pressure applied in presses or autoclaves.

Concept / Approach:
During vulcanization, sulphur atoms form cross-links between polymer chains, creating a three-dimensional network. This reduces creep, improves elasticity at service temperatures, and enhances wear and chemical resistance.

Step-by-Step Solution:

Verification / Alternative check:
Material tests post-vulcanization show higher tensile strength, tear resistance, and set properties compared to raw rubber.

Why Other Options Are Wrong:

• Painting or washing: surface treatments, not structural cross-linking.
• Melting: rubber is thermoset-like when vulcanized and does not melt; raw rubber softens but vulcanization is a chemical process, not simple melting.
• Cryogenic hardening: unrelated to cross-link formation typical of vulcanization.

Common Pitfalls:
Over-curing leads to embrittlement; under-curing leaves weak, tacky material. Proper temperature–time profiles are essential.

Final Answer: