Editing Polyvinyl chloride (section)

==Production==
Polyvinyl chloride is produced by [[polymerization]] of the [[vinyl chloride]] [[monomer]] (VCM), as shown.<ref>{{Cite book|title= Plastics technology handbook | first1= Manas | last1=Chanda| first2= Salil K.|last2= Roy|publisher = CRC Press|year = 2006|pages=1–6|isbn = 978-0-8493-7039-7}}</ref>
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| [[File:Vinyl chloride Polymerization V1.svg|class=skin-invert-image|400px|The polymerisation of vinyl chloride]]
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About 80% of production involves [[suspension polymerization]]. [[Emulsion polymerization]] accounts for about 12%, and [[bulk polymerization]] accounts for 8%. Suspension polymerization produces particles with average diameters of 100–180&nbsp;μm, whereas emulsion polymerization gives much smaller particles of average size around 0.2&nbsp;μm. VCM and water are introduced into the reactor along with a polymerization initiator and other additives. The contents of the reaction vessel are pressurized and continually mixed to maintain the suspension and ensure a uniform particle size of the PVC resin. The reaction is [[exothermic]] and thus requires cooling. As the volume is reduced during the reaction (PVC is denser than VCM), water is continually added to the mixture to maintain the suspension.<ref name=ullmannPVC>{{Ullmann |first=M. W.|last=Allsopp|first2=G.|last2=Vianello|title=Poly(Vinyl Chloride)|year=2012|doi=10.1002/14356007.a21_717}}</ref>

PVC may be manufactured from [[ethylene]], which can be produced from either [[naphtha]] or [[ethane]] feedstock.<ref name="Nikkei Asian Review">{{cite web|url=https://asia.nikkei.com/Business/Companies/Shin-Etsu-Chemical-to-build-1.4bn-polyvinyl-chloride-plant-in-US|title=Shin-Etsu Chemical to build $1.4bn polyvinyl chloride plant in US|website=Nikkei Asian Review|language=en-GB|access-date=24 July 2018|archive-date=24 July 2018|archive-url=https://web.archive.org/web/20180724123305/https://asia.nikkei.com/Business/Companies/Shin-Etsu-Chemical-to-build-1.4bn-polyvinyl-chloride-plant-in-US|url-status=live}}</ref>

===Microstructure===
The [[polymer]]s are linear and are strong. The [[monomers]] are mainly arranged head-to-tail, meaning that [[chloride]] is located on alternating carbon centres. PVC has mainly an [[Tacticity#Polymers|atactic stereochemistry]], which means that the relative [[stereochemistry]] of the chloride centres are random.  Some degree of [[syndiotactic]]ity of the chain gives a few percent crystallinity that is influential on the properties of the material.  About 57% of the mass of PVC is [[chlorine]]. The presence of chloride groups gives the polymer very different properties from the structurally related material [[polyethylene]].<ref>Handbook of Plastics, Elastomers, and Composites, Fourth Edition, 2002 by The McGraw-Hill, Charles A. Harper Editor-in-Chief. {{ISBN|0-07-138476-6}}</ref> At 1.4 g/cm<sup>3</sup>, PVC's density is also higher than structurally related plastics such as [[polyethylene]] (0.88–0.96 g/cm<sup>3</sup>) and [[polymethylmethacrylate]] (1.18 g/cm<sup>3</sup>).

=== Producers ===
About half of the world's PVC production capacity is in [[China]], despite the closure of many Chinese PVC plants due to issues complying with environmental regulations and poor capacities of scale. The largest single producer of PVC as of 2018 is [[Shin-Etsu Chemical]] of [[Japan]], with a global share of around 30%.<ref name="Nikkei Asian Review"/>