Difference between low density polyethylene and high density polyethylene.

Difference between low density polyethylene (LDPE) and high density polyethylene (HDPE).

Density

Low density polyethylene has low density than high density polyethylene.

High density polyethylene has high density than low density polyethylene.

Synthesis

Low density polyethylene is prepared by heating pure ethylene to 350-570K under high pressure (1000-2000 atm) in the presence of traces of oxygen or peroxide initiator (catalyst) which initiates polymerisation.

High density polyethylene is prepared by heating ethene in a hydrocarbon solvent at about 333-343K under pressure of 6-7 atm in the presence of a catalyst such as triethylaluminium and titanium tetrachloride (known as Zeiglar Natta catalyst).

Low density polyethylene and High density polyethylene.

Structure

Low density polyethylene has lots of branching.

High density polyethylene has less branch.

Strength

HDPE is stronger than LDPE.

Low density polyethylene vs high density polyethylene.

Flexibility

Low density polyethylene is very flexible.

High density polyethylene is more rigid  than LDPE.

Transparency

High density polyethylene is less transparent than low density polyethylene.

Chemical properties

Low density polyethylene is chemically inert. Exposure to light and oxygen results in loss of strength and loss of tear resistance.

High density polyethylene is chemically inert. Next