Why rubber is vulcanised : The Transformation of Rubber into a Modern Engineering Material

Rubber, in its natural form, is a remarkable material - elastic, waterproof, and insulative. However, natural rubber, tapped from the sap of rubber trees, has limitations in strength, durability, and temperature stability. The solution to these limitations is a process discovered in the 19th century by Charles Goodyear - vulcanization. This article delves into why rubber is vulcanized, transforming it into a versatile material suited for a myriad of modern applications.

The Need for Vulcanization

• Improved Durability: Natural rubber is prone to wear and tear. Vulcanization significantly increases its durability, making it suitable for products like tires, conveyor belts, and industrial components.
• Temperature Stability: Without vulcanization, rubber becomes brittle in cold temperatures and sticky in hot conditions. Vulcanized rubber maintains its elasticity and form over a broader temperature range.
• Increased Elasticity and Strength: Vulcanization enhances the natural elasticity of rubber, making it stretch further without breaking and return to its original shape more effectively.
• Resistance to Chemicals: Unvulcanized rubber is highly reactive to chemicals. Vulcanization increases its resistance to oils, solvents, and other chemicals.

The Vulcanization Process

1. Adding Sulfur: The key to vulcanization is the addition of sulfur to raw rubber. The amount of sulfur varies depending on the desired properties - more sulfur generally results in harder rubber.
2. Heating: The rubber-sulfur mixture is then heated. This heat causes sulfur atoms to form cross-links between the polymer chains of the rubber.
3. Creating Cross-Links: These cross-links transform the rubber from a sticky, pliable mass into a strong, elastic material. The more cross-links, the stronger and less elastic the rubber becomes.

Vulcanization in Practice

• Tire Manufacturing: Tires are perhaps the most well-known application of vulcanized rubber. The process gives tires the necessary strength and durability to withstand road wear and temperature variations.
• Medical Supplies: Items like gloves and catheters benefit from vulcanization, gaining the necessary elasticity and strength while being safe for medical use.
• Industrial Uses: Hoses, seals, and gaskets must withstand pressure, temperature changes, and chemical exposure, all made possible by vulcanization.

The Evolution of Vulcanization

• Modern Variations: Today, vulcanization has evolved. Besides sulfur, other chemicals and methods are used to vulcanize rubber for specific applications.
• Eco-Friendly Practices: The rubber industry also focuses on making vulcanization more environmentally friendly, reducing emissions and energy use.

Conclusion

Vulcanization transformed rubber from a curious natural substance into an indispensable material in modern engineering and manufacturing. This process, simple yet revolutionary, has enabled rubber to play a vital role in industries ranging from automotive to healthcare. Understanding the why and how of vulcanization is key to appreciating the ubiquitous presence and importance of rubber in our daily lives.