Addition Polymerisation

is a process where long chainlike molecules are formed by the addition of large numbers of mers. Polyethylene is produced by this polymerisation

mechanism. The ethylene molecule or mer consists of a strong and a weak bond between the carbon atoms. A catalyst or a free radical, which has

an unpaired electron in its outer shell is added to the ethylene molecule. The weak bond is attached and one of its electrons is taken by the radical

leaving the other free. Now the attached ethylene molecule behaves like a radical and the process is repeated continuously. Long chains bond

together in seconds until the reaction is terminated by a chain stopper.

Addition polymerisation contains bonds held together by weak Van der Waals forces which are easily overcome by heat or pressure.

Therefore a Thermoplastic material is produced.