Briefly describe the following terms giving one example of each:
(i) Polyolefins   
(ii) Polyamides
(iii) Polyesters    
(iv) Polydienes

(i) The polymers derived from unsaturated hydrocarbons are called polyolefins. Examples are:

(ii)    The polymers having amide linkages in the chain are known as polyamides. Examples are:
(a)    Nylon–66 (from hexamethylene diammmine and adipic acid)    
(b)    Nylon–6 (from caprolactam)

(iii)    The polymers having ester linkages in the chain are known as polyesters. Examples are:
(a)    Terylene (from terephthalic acid and glycol)
(b)    Glyptal or alkyd resin (from phthalic acid and glycol)

(iv)    Polymers of this class are synthetic rubber. Examples are:



(b) Buna-S (from butadiene and styrene)