Free radical mechanism for the polymerisation of ethane has the following steps.

1. Chain initiation - The chain is initiated by free radicals, Ra , produced by reaction between some of the ethene and the oxygen initiator like benzoyl peroxide

2. Chain propagation - Each time a free radical hits an ethene molecule a new bigger free radical is formed.

3. Chain termination - At the end two free radicals hit each other producing the final molecule. The process stops here because no new free radicals are formed.