Polyethylene is a long chain polymer produced by the polymerization reaction of liquid ethylene at high temperatures and pressures. It is a solid plastic which has a milky transparent appearance.

The discovery of polyethylene in the 1930s greatly aided the Allied war effort in World War II. Polyethylene was used as insulation for cables vital to the Allied information network. Polyethylene was accidently discovered by J. Swallow and M. Perrin at Imperial Chemical Industries in Britain. In 1933, while researching the effects of high pressure on chemical reactants, a fellow scientist, R. Gibson, managed to produce a waxy solid from ethylene and benzaldehyde. He repeated the experiment with ethylene alone with no success. The experiment had taken place at 280°F (138 °C) with ethylene at a pressure of 1,400 atmospheres. Theorizing that a higher pressure was needed, the three colleagues set to work designing and building improved laboratory equipment...