Rubber Hardening through Vulcanisation Process

Vulcanisation is a chemical process used to harden rubber by adding sulphur. It involves the cross-linking of rubber molecules through the formation of chemical bonds, resulting in improved elasticity, strength, and durability of the material.

Process of Vulcanisation:
1. Cross-linking: The vulcanisation process starts by adding sulphur to the raw rubber. The sulphur molecules react with the rubber polymer chains, forming cross-links between them. These cross-links create a three-dimensional network, giving the rubber its desired properties.
2. Heat and Pressure: Once the sulphur is added, the rubber is exposed to heat and pressure. The combination of heat and pressure accelerates the vulcanisation process, allowing the sulphur to effectively cross-link the rubber chains.
3. Curing: The rubber is then cured in a mold or under controlled conditions to maintain its shape and improve its mechanical properties. The curing process allows the sulphur to fully react with the rubber, creating a stable and durable product.

Importance of Sulphur:
Sulphur is a crucial component in the vulcanisation process due to its ability to form strong chemical bonds with the rubber polymer chains. These bonds, known as sulphur bridges or cross-links, provide stability and strength to the rubber material. Without the presence of sulphur, the rubber would remain soft and tacky, lacking the desired mechanical properties.

Advantages of Vulcanised Rubber:
1. Improved Strength: Vulcanisation increases the tensile strength of rubber, making it more resistant to stretching and tearing.
2. Enhanced Elasticity: The cross-links formed during vulcanisation allow the rubber to recover its original shape after being deformed, thus improving its elasticity.
3. Resistance to Heat and Chemicals: Vulcanised rubber exhibits greater resistance to heat, chemicals, and environmental factors, making it suitable for various applications.
4. Reduced Swelling and Softening: Vulcanisation reduces the tendency of rubber to swell or soften when exposed to solvents or oils, enhancing its durability.

In conclusion, the addition of sulphur in the vulcanisation process is essential for hardening rubber. Sulphur forms cross-links between rubber polymer chains, resulting in improved strength, elasticity, and resistance to heat and chemicals. Vulcanised rubber offers numerous advantages over raw rubber, making it a widely used material in various industries.