Question

To have practical applications why are cross links required in rubber?

Answer 1

Importance of cross-linking:

• A few cross-links are introduced between the polymer chains of natural rubber by the vulcanisation of rubber with sulphur.
• These cross-links help the polymer to retain its original shape after the external force is removed.
• When the rubber gets hot, then due to cross-links, various strands cannot flow past each other, and the rubber retains its shape.
• Thus, these cross-links enhance the elastic property of rubber and make it stiffer.
• For example: In vulcanised rubber, many chains of polyisoprene are covalently bonded to S atoms.