Polythene (polyethylene):Properties, Production & Uses
Properties and Uses
|Property||Low Density Polyethylene
|High Density Polyethylene
|Crystallinity||low crystallinity (50-60% crystalline)
Main chain contains many side chains of 2-4 carbon atoms leading to irregular packing and low crystallinity (amorphous)
|highly crystalline (>90% crystalline)
contains less than 1 side chain per 200 carbon atoms in the main chain leading to long linear chains that result in regular packing and high crystallinity
|Flexibility||more flexible than HDPE due to lower crystallinity||more rigid than LDPE due to higher crystallinity|
|Strength||not as strong as HDPE due to irregular packing of polymer chains||strong as a result of regular packing of polymer chains|
|Heat Resistance||retains toughness & pliabilty over a wide temperature range, but density drops off dramatically above room temperature.||useful above 100oC|
|Transparency||good transparency since it is more amorphous (has non-crystalline regions) than HDPE||less transparent than LDPE because it is more crystalline|
lower density than HDPE
higher density than LDPE
|Chemical Properties||chemically inert
Insolvent at room temperature in most solvents.
Good resistance to acids and alkalis.
Exposure to light and oxygen results in loss of strength and loss of tear resistance.
|Uses||sandwich bags, cling wrap, car covers, squeeze bottles, liners for tanks and ponds, moisture barriers in construction||freezer bags, water pipes, wire and cable insulation, extrusion coating|