Preparation of Low density polyethylene (LDPE) :

It is formed by heating ethene at 200°C to 300°C and at 1000 atm pressure using small amount of oxygen as acatalyst. Oxygen form peroxide and reaction is initiated. This is a branched chain polymer, as growing chain abstracts hydrogen atom from the middle of the chain and the branch grows.

i) Growing chain unit takes proton from another to form secondary free radical.

ii) Secondary free radical combine with another molecule ethylene to form branched polymer and thus branch grow.


LDPE have low m.p. It is used as insulation for cables, as packing bags, making toys.

This LDPE is chemically inert and tough but mechanically weak.