Rubber is a natural or synthetic polymer with elastic properties, widely used in industries and daily life. The most significant transformation in its utility was the discovery of vulcanization, which improves strength, elasticity, and durability. Rubber and Vulcanization
1. Natural Rubber
Natural rubber is a polymer of isoprene (2-methyl-1,3-butadiene) extracted from the latex of Hevea brasiliensis trees. It is soft, sticky, and elastic but has limited resistance to heat and oxidation.
2. Synthetic Rubber
Synthetic rubbers are man-made polymers that mimic natural rubber but offer better properties. Common examples include:
- Styrene-Butadiene Rubber (SBR): Major use in automobile tires.
- Neoprene: Resistant to oil and chemicals.
- Buna-N: Used in fuel hoses and gaskets.
3. Vulcanization Process
Vulcanization is a chemical process where rubber is heated with sulfur (or other agents), creating cross-links between polymer chains and forming a strong 3D network.
- Inventor: Charles Goodyear (1839).
- Conditions: 140–160°C with 1–3% sulfur.
- Cross-linking: Sulfur forms disulfide bridges between chains.
4. Effects of Vulcanization
- Increases elasticity and resilience.
- Improves tensile strength and abrasion resistance.
- Reduces tackiness and increases thermal stability.
- Enhances resistance to oxidation, solvents, and wear.
5. Applications of Vulcanized Rubber
- Automobile tires and tubes
- Seals, gaskets, and hoses
- Footwear and sporting goods
- Industrial belts and flooring
- Medical gloves and elastic bands
Quiz: Rubber and Vulcanization
Q1. What is the main monomer of natural rubber?
A) Ethylene
B) Propylene
C) Isoprene
D) Butadiene
✔ Answer: C — Natural rubber is a polymer of isoprene.
Q2. Purpose of vulcanization?
A) To melt rubber
B) To color rubber
C) To improve strength and elasticity
D) To make rubber soluble
✔ Answer: C — Vulcanization increases elasticity and durability.
Q3. Who discovered vulcanization?
A) John Dalton
B) Charles Goodyear
C) Alfred Nobel
D) Leo Baekeland
✔ Answer: B — Charles Goodyear in 1839.
Q4. Which of the following is a synthetic rubber?
A) Chitosan
B) Nylon-6
C) Neoprene
D) Polyethylene
✔ Answer: C — Neoprene is a synthetic rubber.
FAQs on Rubber and Vulcanization
Q1: Why is natural rubber not suitable for hot conditions?
Ans: Because it becomes soft and sticky due to low thermal stability.
Q2: What is the role of sulfur in vulcanization?
Ans: Sulfur forms cross-links between rubber chains, making them stronger and elastic.
Q3: Which industry consumes the maximum vulcanized rubber?
Ans: The automobile industry (tires and tubes).
Related Reading: Applications of Polymers | Rubber in Britannica
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