Polyethylene is a white, colourless thermoplastic that is available in a few variants with different characteristics, the most common of which are:
- LD (low density)-polyethylene: Density 0.910 – 0.940 g/cubic centimetre.
- HD (high density)-polyethylene: Density 0.940 – 0.965 g/cubic centimetre.
- HD polyethylene is more rigid and has a harder surface than LD polyethylene.
Polyethylene is relatively resistant to chemicals (with the exception of strong oxidizing acids and some organic solvents), has low water absorption and can be used together with food. It is also light weight and has good impact strength and a relatively low price. However, PE burns easily and has poor weather durability in its unpigmented form and limited heat resistance. It is also very difficult to glue and difficult to print on. PE has a high linear heat expansion coefficient and low resistance to creeping. The mechanical characteristics are also strongly temperature dependent.
- Very good impact strength across a wide temperature range
- Low water absorption
- Resistant to most chemicals
- Can be used in contact with food
- Is available in multiple variants with varying melting indexes and molecular weights from very weak to semi-rigid material
- Rendered more rigid with fillers or fibre glass
- Low price
- Very high coefficient of longitudinal expansion
- Low resistance to creep under load
- Poor fatigue strength than polypropylene
- Burns fiercely High shape shrinkage
- Sensitive to stress corrosion
- Poor weather resistance (if not black)
- Low scratch resistance
- Mechanical properties strongly temperature dependent
Household items, toys, bottles, pipes, buckets, accumulator containers, cable insulation, petrol tanks, packaging film, containers, linings, sealing rings, etc. Note: Also available in a mid-density (MD) variant, which is not very common, however.