Polyethylene or polythene is the most common plastic in use today. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes, containers including bottles, etc.)

The properties of polyethylene can be divided into mechanical, chemical, electrical, optical, and thermal properties.

Polyethylene is of low strength, hardness and rigidity, but has a high ductility and impact strength as well as low friction. It shows strong creep under persistent force, which can be reduced by addition of short fibers. It feels waxy when touched.

Polyethylene consists of nonpolar, saturated, high molecular weight hydrocarbons. Therefore, its chemical behavior is similar to paraffin. The individual macromolecules are not covalently linked. Because of their symmetric molecular structure, they tend to crystallize; overall polyethylene is partially crystalline. Higher crystallinity increases density and mechanical and chemical stability.