Editing Polyvinyl chloride (section)

==Additives==
The product of the polymerization process is unmodified PVC. Before PVC can be made into finished products, it always requires conversion into a compound by the incorporation of additives (but not necessarily all of the following) such as [[heat stabilizer]]s, [[UV stabilizers in plastics|UV stabilizers]], plasticizers, processing aids, impact modifiers, thermal modifiers, fillers, [[flame retardant]]s, [[biocides]], blowing agents and smoke suppressors, and, optionally, pigments.<ref name=UllmannPlasticizer>David F. Cadogan and Christopher J. Howick "Plasticizers" in Ullmann's Encyclopedia of Industrial Chemistry 2000, Wiley-VCH, Weinheim. {{doi| 10.1002/14356007.a20_439}}</ref> The choice of additives used for the PVC finished product is controlled by the cost performance requirements of the end use specification (underground pipe, window frames, intravenous tubing and flooring all have very different ingredients to suit their performance requirements). Previously, [[polychlorinated biphenyl]]s (PCBs) were added to certain PVC products as flame retardants and stabilizers.<ref>{{cite web|last1 = Karlen|first1 = Kaley|title = Health Concerns and Environmental Issues with PVC-Containing Building Materials in Green Buildings|url = http://www.calrecycle.ca.gov/publications/Documents/GreenBuilding%5C43106016.pdf|website = Integrated Waste Management Board|publisher = California Environmental Protection Agency, US|access-date = 26 August 2015|archive-date = 5 February 2016|archive-url = https://web.archive.org/web/20160205053614/http://www.calrecycle.ca.gov/publications/Documents/GreenBuilding%5C43106016.pdf|url-status = live}}</ref>

===Plasticizers===
{{Main|Plasticizers}}
Among the [[Commodity plastics|common plastics]], PVC is unique in its acceptance of large amounts of plasticizer with gradual changes in physical properties from a rigid solid to a soft gel,<ref name="additives handbook">{{cite book |last1=Krauskopf |first1=Leonard G. |title=Plastics additives handbook |date=2009 |publisher=Carl Hanser Verlag |location=Munich |isbn=978-3-446-40801-2 |pages=485–511 |edition=6. |chapter=3.13 Plasticizers}}</ref> and almost 90% of all plasticizer production is used in making flexible PVC.<ref>David F. Cadogan and Christopher J. Howick "Plasticizers" in Ullmann's Encyclopedia of Industrial Chemistry 2000, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a20_439}}</ref><ref name="plasticisers1">{{cite web |url=https://www.plasticisers.org/factsheet/plasticisers-factsheets |title=factsheets - Plasticisers - Information Center |publisher=Plasticisers |date= |accessdate=2022-02-19 |archive-date=9 February 2022 |archive-url=https://web.archive.org/web/20220209124924/https://www.plasticisers.org/factsheet/plasticisers-factsheets/ |url-status=live }}</ref> The majority is used in films and cable sheathing.<ref name=ceresana>{{cite web |title=Plasticizers Market Report |url=https://www.ceresana.com/en/market-studies/chemicals/plasticizers/ |website=Ceresana|access-date=7 January 2023}}</ref> Flexible PVC can consist of over 85% plasticizer by mass, however unplasticized PVC (UPVC) should not contain any.<ref name=table />

{| class="wikitable" style="width:71em"
|+ PVC properties as a function of phthalate plasticizer level<ref name=table>{{cite book |last1=Krauskopf |first1=L. G. |title=Plastics additives handbook |date=2009 |publisher=[[Carl Hanser Verlag]] |location=Munich |isbn=978-3-446-40801-2 |page=495 |edition=6.}}</ref>
! !!  Plasticizer content  (% [[DINP]] by weight) !! [[Specific gravity]] (20&nbsp;°C) !! [[Shore hardness]] <BR /><small>(type A, 15 s)</small> !! [[Flexural rigidity|Flexural stiffness]]  ([[Megapascal|Mpa]]) !! [[Ultimate tensile strength|Tensile strength]] (Mpa) !!  Elongation at break (%) !! Example applications 
|-
| Rigid || 0 || 1.4 ||  || 900 || 41 || <15 || Unplasticized PVC (UPVC): window frames and sills, doors, [[Plastic pipework#uPVC (unplasticized Polyvinyl Chloride)|rigid pipe]]
|-
| Semi-rigid || 25 || 1.26 || 94 || 69 || 31 || 225 || [[Sheet vinyl flooring|Vinyl flooring]], flexible pipe, thin films ([[stretch wrap]]), advertising banners 
|-
| Flexible || 33 || 1.22 || 84 || 12 || 21 || 295 ||  Wire and cable insulation, flexible pipe 
|-
| Very Flexible || 44 || 1.17 || 66 || 3.4 || 14 || 400 || Boots and clothing, inflatables, 
|-
| Extremely Flexible || 86 || 1.02 || < 10 ||  ||  ||  || Fishing lures ([[soft plastic bait]]), [[polymer clay]], [[plastisol]] inks
|}

====Phthalates====
{{Main|Phthalate}}
The most common class of plasticizers used in PVC is phthalates, which are diesters of [[phthalic acid]].  Phthalates can be categorized as high and low, depending on their molecular weight. Low phthalates such as [[Bis(2-ethylhexyl) phthalate]] (DEHP) and [[Dibutyl phthalate]] (DBP) have increased health risks and are generally being phased out. High-molecular-weight phthalates such as [[diisononyl phthalate]] (DINP) and [[diisodecyl phthalate]] (DIDP) are generally considered safer.<ref name="plasticisers1"/>

While DEHP has been medically approved for many years for use in medical devices, it was permanently banned for use in children's products in the US in 2008 by US Congress;<ref>{{cite web |url=https://noharm-uscanada.org/issues/us-canada/phthalates-and-dehp |archive-url=https://web.archive.org/web/20140630031138/https://noharm-uscanada.org/issues/us-canada/phthalates-and-dehp |url-status=dead |archive-date=30 June 2014 |title=Phthalates and DEHP |date=29 April 2013 |publisher=Health Care Without Harm |access-date=23 July 2021 }}</ref> the PVC-DEHP combination had proved to be very suitable for making blood bags because DEHP stabilizes red blood cells, minimizing [[hemolysis]] (red blood cell rupture). However, DEHP is coming under increasing pressure in Europe. The assessment of potential risks related to phthalates, and in particular the use of DEHP in PVC medical devices, was subject to scientific and policy review by the European Union authorities, and on 21 March 2010, a specific labeling requirement was introduced across the EU for all devices containing phthalates that are classified as CMR (carcinogenic, mutagenic or toxic to reproduction).<ref>[http://ec.europa.eu/health/scientific_committees/emerging/docs/scenihr_o_047.pdf Opinion on The safety of medical devices containing DEHP plasticized PVC or other plasticizers on neonates and other groups possibly at risk (2015 update)] {{Webarchive|url=https://web.archive.org/web/20160203200221/http://ec.europa.eu/health/scientific_committees/emerging/docs/scenihr_o_047.pdf |date=3 February 2016 }}. Scientific Committee on Emerging and Newly-Identified Health Risks (25 June 2015).</ref> The label aims to enable healthcare professionals to use this equipment safely, and, where needed, take appropriate precautionary measures for patients at risk of over-exposure.<ref>{{cite web |url=https://www.plasticisers.org/?s=DEHP |title=You searched for DEHP - Plasticisers - Information Center |publisher=Plasticisers |date= |accessdate=2022-02-19 |archive-date=9 February 2022 |archive-url=https://web.archive.org/web/20220209114052/https://www.plasticisers.org/?s=DEHP |url-status=live }}</ref>

[[File:Bis(2-ethylhexyl)phthalate.svg|class=skin-invert-image|thumb|right|220px|[[Bis(2-ethylhexyl) phthalate]] was a common plasticizer for PVC but is being replaced by higher molecular weight phthalates.]]

===Metal stabilizers===
BaZn stabilisers have successfully replaced cadmium-based stabilisers in Europe in many PVC semi-rigid and flexible applications.<ref>[https://web.archive.org/web/20150726001713/http://www.stabilisers.eu/stabilisers-types/liquid-stabilisers Liquid stabilisers]. Seuropean Stabiliser Producers Association</ref>

In Europe, particularly Belgium, there has been a commitment to eliminate the use of cadmium (previously used as a part component of heat stabilizers in window profiles) and phase out lead-based heat stabilizers (as used in pipe and profile areas) such as liquid autodiachromate and calcium polyhydrocummate by 2015. According to the final report of ''Vinyl 2010'',<ref>[https://web.archive.org/web/20140519042304/http://www.vinylplus.eu/uploads/Progress_Report_2011/Vinyl2010-ProgressReport2011_English.pdf Vinyl 2010]. The European PVC Industry's Sustainable Development Programme</ref> cadmium was eliminated across Europe by 2007. The progressive substitution of lead-based stabilizers is also confirmed in the same document showing a reduction of 75% since 2000 and ongoing. This is confirmed by the corresponding growth in calcium-based stabilizers, used as an alternative to lead-based stabilizers, more and more, also outside Europe.<ref name=ullmannPVC/>

===Heat stabilizers===
Some of the most crucial additives are heat stabilizers.  These agents minimize [[dehydrochlorination|loss of HCl]], a degradation process that starts above 70&nbsp;°C (158&nbsp;°F) and is [[autocatalytic]].  Many diverse agents have been used including, traditionally, derivatives of [[Heavy metal (chemistry)|heavy metal]]s (lead, cadmium).  Metallic soaps (metal "salts" of [[fatty acid]]s such as [[calcium stearate]]) are common in flexible PVC applications.<ref name=ullmannPVC/>