polyethylene glycol (PEG): see glycol.

polyethylene, widely used plastic. It is a polymer of ethylene, CH₂--CH₂, having the formula (-CH₂-CH₂-)_n, and is produced at high pressures and temperatures in the presence of any one of several catalysts, depending on the desired properties for the finished product. Polyethylene is resistant to water, acids, alkalies, and most solvents. Its many applications include films or sheets for packaging, shower curtains, unbreakable bottles, pipes, pails, drinking glasses, and insulation for wire and cable.