Discuss the main purpose of vulcanisation of rubber.

Explanation

Natural rubber has the folowing disadvantages:
(i)It is soft and sticky and becomes more so at high temperature and brittle atlow temperature.That is why it is used at low temperature range`(280-330K)`where its elasticity maintained.
(ii)It is attacked by oxygen and othe oxidising agents
(iii)It has a high water absorption capacity,low tensile strength ,and low resistance to abrasion.
(iv)It is reactive to organic solvents.
Therefore ,natural rubber is vulcanised by heating it with about`(3-5%)`sulpher at`(373-415K)`.During vulcanisation ,sulphur bridges or the cross-links between polymer chains are introduced.Thus,vulcanised rubber so contained has excellent elasticity over a wide range of temperature,low water absorption capacity,and is resistant to the action of oxygen and other oxidising agents.