CompTox Dashboard (EPA)
|Melting point||115–135 °C (239–275 °F; 388–408 K)|
|−9.67×10−6 (HDPE, SI, 22 °C)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most common plastic in use today. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bottles, etc.). As of 2017[update], over 100 million tonnes of polyethylene resins are being produced annually, accounting for 34% of the total plastics market.
Many kinds of polyethylene are known, with most having the chemical formula (C2H4)n. PE is usually a mixture of similar polymers of ethylene, with various values of n. It can be low-density or high-density: low-density polyethylene is extruded[verification needed] using high pressure (1000–5000 atm) and high temperature (520 kelvins), while high-density polyethylene is extruded[verification needed] using low pressure (6–7 atm) and low temperature (333–343 K). Polyethylene is usually thermoplastic, but it can be modified to become thermosetting instead, for example, in cross-linked polyethylene.