1. When alkenes are heated with free radical initiator such as benzoyl peroxide, they undergo polymerisation reaction. For example, styrene polymerises to polystrene when it is heated with a peroxide initator. The mechanism involves the following steps.
2. Initiation – Formation of free radical.
3. Propagation step.
4. Chain growth will continue with the successive addition of several thousands of monomer units.
5. Termination: The above chain reaction can be stopped by stopping the supply of monomer or by coupling of two chains or reaction with an impurity such as oxygen.