How are polythene and neoprene prepared?
Preparation of polythene:
The monomer used is ethane. It is an addition polymer. There are two ways of preparation of ethane.
Low-density polymer (LDPE): It is formed by heating ethene at 200° to 300°C and at 1000 atm pressure using a small amount of oxygen as a catalyst.
Oxygen forms peroxide and the reaction is initiated.
High-density polymers (HDPE): The catalyst used is called Ziegler–Natta catalyst. It is titanium chloride and triethyl aluminium [TiCI4 + (C2H5)3 Al].
The polymerisation takes place at 373 K, 6−7 atm pressure in the presence of the Ziegler–Natta catalyst.
Preparation of neoprene:
2-Chlorobuta-1,3-diene in the presence of benzoyl peroxide forms neoprene. Here, 2-chlorobuta-1,3-diene (chloroprene) acts as a monomer.