Polyethylene (PE)

Polyethylene (abbreviation PE, previously called polyethylene, occasionally polyethene) is a thermoplastic polymer produced by polymerisation of ethene [CH₂ = CH₂] with the simplified chain structure formula

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Polyethylene belongs to the polyolefins group. Substitution of hydrogen produces polyvinyls, e.g. polyvinyl chloride.

Polyethylene is partly crystalline. Increased crystallinity increases the density and and the mechanical and chemical stability.

An overview of the properties

• Low density (0.87–0.965 g/cm³)
• High viscosity and elongation at break
• Good sliding performance, low wear (compare with PE-UHMW)
• Temperature resistance from –85 °C to +90 °C (depends on crystallinity, the lower it is the less resistant the material is to high temperatures. In types with a crystallinity of approx. 20 % the upper temperature resistance limit is 30–50 °C)
• Visual, milky white (opaque), the lower the crystallinity (and therefore the density) the more transparent the material. Below a density of 0.9 g/cm³, PE is transparent.
• very good electrical and dielectric performance (specific volume resistance approx. 10¹⁸ Ohm/cm)
• very low water absorption
• very good chip removal and chipless machining
• burns well; residue free: CO₂ + H₂O as combustion products
• PE is resistant to almost all polar solvents (T < 60 °C), acids, lyes, water, alcohols, oil, PE-HD and benzine

Polyethylene is worldwide the most produced plastic and accounts for approx. 29 percent of all plastic. 52 million tonnes were produced in 2001.