Editing Polyethylene (section)

===Monomer===
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| footer = Ethylene (ethene)
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The ingredient or [[monomer]] is [[ethylene]] ([[IUPAC]] name ethene), a [[gas]]eous [[hydrocarbon]] with the formula C<sub>2</sub>H<sub>4</sub>, which can be viewed as a pair of [[methylene group]]s (−{{chem|CH|2}}−) connected to each other. Typical specifications for PE purity are <5&nbsp;ppm for water, oxygen, and other [[alkene]]s contents. Acceptable contaminants include N<sub>2</sub>, ethane (common precursor to ethylene), and methane. Ethylene is usually produced from [[Cracking (chemistry)|petrochemical sources]], but is also generated by [[Ethanol#Dehydration|dehydration of ethanol]].<ref name="Ullmann"/>