Polyethylene is a flexible, waxy, transparent and thermoplastic substance. It gradually loses its flexibility when exposed to sunlight and/or humidity.
PE films have low steam permeability, are easily pervious to the vapours of organic substances, are not resistant to hydrocarbons and their chlorine derivatives. Are resistant to acid, base and salt solutions, and to low temperature. Used for the manufacture of: films, pipes, containers. Polyethylene fishing lines or woven ropes are often used in angling, sailing and climbing.
Types
Specific properties depend on the reaction conditions (pressure, temperature, catalyst). Four types of polyethylene can be distinguished:
• HDPE (high density PE, PEHD) – low-pressure PE with high density (lack of chain branching provide high density and strong intermolecular forces). Density – 0.94-0.97 g/cm³,
• MDPE (medium density PE). Density – 0.926-0.940 g/cm³.
• LDPE (low density PE) – high-pressure PE with low density. Density – 0.915-0.935 g/cm³,
• LLDPE (linear low density PE) – low-pressure linear PE with low density (short, unbranched chains are produced by copolymerization of ethylene with longer-chain olefins). Density – 0.915-0.935 g/cm³.
Polyethylene or polyethene – a polymer of ethene. Industrial abbreviation: (PE).