Polymerization occurs only in Alkenes! People always make that mistake , it cannot occur in Alkanes because they are saturated Hydrocarbons [ meaning there are no double bonds to break open ]
H H
take ethene for example : - | |
H - C = C - H
here the double bond can be broken by the process of addition reaction to form an open ended ethene also known as an ethene monomer.
when more of these open ended ethene monomers combine together they form a polymer known as polyethen or polythene this is an addition polymer.
but on the other hand : H H
| |
H - C - C - H
| |
H H
ethane has no double bonds to break therfore it cannot take part in reactions.
and thats why short chain alkanes are preferred over longer ones as they are good fuels and also they are used to enrich the petrol.