Tyre technology — meaning of vulcanization In automotive service, the term ‘‘vulcanizing’’ rubber generally means which process?
Correct Answer: heating rubber under pressure (typically with sulphur) to cross-link and strengthen it
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:
Prepare compound with rubber, sulphur, accelerators, and fillers.Apply heat and pressure for a controlled time to promote cross-linking.Achieve desired hardness, resilience, and strength for the application.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:
heating rubber under pressure (typically with sulphur) to cross-link and strengthen it