Write the structure of Monomers used to obtain the following polymers:

(a) Natural rubber

(b) PVC

(c) Nylon- 6,6

OR

Write the mechanism of free radical polymerization of ethene.

(a) The monomer of natural rubber is isoprene (2-methyl-1, 3-butadiene).

(b) The monomer of PVC is Vinyl chloride.

(c) The monomers of Nylon- 6,6 is are hexamethylenediamine with adipic acid.

(Adipic acid) (hexamethylenediamine)

OR

The process of free radical polymerization of ethene starts with the addition of phenyl free radical formed by the peroxide to the ethene double bond thus generating a new and larger free radical. This step is called chain initiating step.

As this radical reacts with another molecule of ethene, another bigger sized radical is formed. The repetition of this sequence with new and bigger radicals carries the reaction forward and the step is termed as chain propagating step.

Ultimately, at some stage the product radical thus formed reacts with another radical to form the polymerised product. This step is called the chain terminating step.