low density and high density for barbz

Question 1

Low density poly(ethene)

Answer 1

Low density poly(ethene) (polythene) is made by polymerising ethene
at high pressure and high temperature via a free-radical mechanism.
This produces a polymer with a certain amount of chain branching.
This is a consequence of the rather random nature of free-radical
reactions. The branched chains do nOL pack together particularly well
and the product is quite flexible, stretches well and has a fairly low
density. These properties make it suitable for packaging (plastic bags),
sheeting and insulation for electrical cables.

Question 2

High density polythene

Answer 2

High density polythene is made at temperatures and pressures little
greater than room conditions and uses a Ziegler-Nalta catalyst,

. This results in a polymer with much less chain
branching (around one branch for every 200 carbons on the main