Question

Which of the following is incorrect regarding High density polythene (HDP)?

• A. Ziegler-Natta catalyst is used in it synthesis
• B. Pressure of 6-7 atmospheres are required
• C. HDP chemically inert and more tough and hard
• D. HDP is a branched structure

Answer 1

The correct option is D HDP is a branched structure

It is formed when addition polymerisation of ethene takes place in a hydrocarbon solvent in the presence of a catalyst such as triethylaluminium and titanium tetrachloride (Ziegler-Natta catalyst) at a temperature of 333 K to 343 K and under a pressure of 6-7 atmospheres. High density polythene (HDP) thus produced, consists of linear molecules as shown below and has a high density due to close packing. Such polymers are also called linear polymers. High density polymers are also chemically inert and more tough and hard. It is used for manufacturing buckets, dustbins, bottles, pipes, etc.
LDP has a branches whereas HDP is a linear structure.

Temperatures and pressure higher than this will favour the formation of Low density polythene(LDP). LDP is chemically inert and tough but
flexible and a poor conductor of electricity. Hence, it is used in the insulation of electricity carrying wires and manufacture
of squeeze bottles, toys and flexible pipes.