Natural rubber has the following drawbacks :

(1) It is soft and sticky at room temperature. At high temperatures, (> 335 K), softness increases.

At low temperatures, (< 283 K), it is brittle.

Hence, to maintain elasticity, natural rubber can be used in the temperature range of 283 K – 335 K.

(2) It can absorb large amounts of water.

(3) It's tensile strength is low and it has low resistance to abrasion.

(4) It is soluble in non-polar solvents.

(5) It is easily attacked by oxidizing agents.

Vulcanization is carried out to improve this property. This process involves heating a mixture of raw rubber with sulphur and other additives at a temperature range between 100°C to 145°C.

After vulcanization sulphur forms cross-links at the reactive sites of double bonds and thus the rubber gets stiffened.