View source for Pliofilm

{{Use mdy dates|date=February 2021}}
{{Short description|Brand of plastic wrap}}
[[File:1973-S Blue Ike (cropped).jpg|thumb|A 1973 [[Eisenhower dollar]] and printed token enclosed in Pliofilm]]
{{multiple image
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| footer = American troops at sea during the Normandy landings, Pliofilm covers can be seen on many of their firearms.
| image1 =American soldiers, hardened and ready, lounge under full fighting equipment on the deck of a Coast Guard assault... - NARA - 196237.jpg
| image2 = Omaha Beach Landing Craft Approaches.jpg
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}}
'''Pliofilm''' was a [[plastic wrap]] made by the [[Goodyear Tire and Rubber Company]] at plants in the US state of [[Ohio]]. Invented in the early 1930s, it was made by dissolving rubber in a [[benzene]] solvent and treating it with gaseous hydrochloric acid. Pliofilm was more stable in a range of humidities than earlier cellulose-based wraps and became popular as a [[food wrap]]. Its manufacture exposed workers to carcinogenic benzene and, when an additive was used to improve durability, caused [[dermatitis]].
Production of Pliofilm was hampered during [[World War II]] because the [[Greater East Asia Co-Prosperity Sphere|Japanese occupation]] of much of [[Southeast Asia]] cut off much of the rubber supply.  During the war years production was given over entirely to military purposes, with Pliofilm being used to wrap machinery and to waterproof firearms. After the war a plant was opened in [[Wolverhampton]], [[England]], and commercial production continued until the late 1980s.
== Manufacture ==
Pliofilm is a transparent film made of [[rubber hydrochloride]].<ref name=cpe>{{cite book |title=Chemical & Process Engineering |date=1945 |publisher=L. Hill Technical Group. |page=206 |url=https://books.google.com/books?id=BxIsAQAAMAAJ }}</ref>  It is impermeable to water and water vapour and non-flammable.<ref name=cpe/><ref>{{cite journal |title=Rubber hydrochloride |journal=Encyclopedic Dictionary of Polymers |date=2007 |pages=852 |doi=10.1007/978-0-387-30160-0_10001 |url=https://link.springer.com/referenceworkentry/10.1007%2F978-0-387-30160-0_10001 |publisher=Springer |isbn=978-0-387-31021-3 |language=en}}</ref>
Pliofilm was manufactured by dissolving [[natural rubber]] in the solvent [[benzene]].<ref name=phr/>  The solution was kept in a tank at around {{convert|10|C|F}} and treated with gaseous [[hydrochloric acid]].<ref name=phr/><ref name=stepek>{{cite book |last1=Štěpek |first1=Jiri |title=Polymers as Materials for Packaging |date=1987 |publisher=E. Horwood Limited |isbn=978-0-85312-677-5 |page=242 |url=https://books.google.com/books?id=MFSaAAAAIAAJ |language=en}}</ref>  The material was then neutralised with an alkali.<ref name=phr>{{cite book |title=Public Health Reports |date=April 1943 |publisher=U.S. Marine Hospital Service |page=625 |url=https://books.google.com/books?id=pLBBAQAAMAAJ |language=en}}</ref>  The product was cast as a sheet on an [[Conveyor belt|endless belt]] which passed through a dryer that drove off the solvent.<ref>{{cite book |title=Packaging Series |date=1955 |publisher=American Management Association |page=73 |url=https://books.google.com/books?id=bfPS06HYKz4C |language=en}}</ref><ref>{{cite book |last1=Stern |first1=Harold Jacob |title=Rubber: Natural and Synthetic |date=1967 |publisher=Maclaren |page=58 |url=https://books.google.com/books?id=WOlGAQAAIAAJ |language=en}}</ref>  The finished product was around 30% chlorine.<ref name=stepek/>  It could be made thinner by stretching whilst being heated and thicknesses of {{convert|0.00075|-|0.025|in|mm}} were sold.<ref>{{cite book |title=Modern Plastics Worldwide World Encyclopedia, with Buyer's Guide |date=1953 |publisher=Plastics Catalogue Corporation |page=182 |url=https://books.google.com/books?id=tscTAAAAIAAJ |language=en}}</ref><ref name=pm/>  Thicker sheets could be produced by laminating the product, combining several sheets with the use of [[rubber cement]].<ref name=phr2>{{cite book |title=Public Health Reports |date=April 1943 |publisher=U.S. Marine Hospital Service |page=626|url=https://books.google.com/books?id=pLBBAQAAMAAJ |language=en}}</ref>
== History and uses ==
Pliofilm was invented by [[Harold J. Osterhof]] at the [[Goodyear Tire and Rubber Company]] in the early 1930s and first marketed in 1934.<ref name=alumnus>{{cite book |title=The Michigan Alumnus |date=September 1970 |publisher=Alumni Association of the University of Michigan |page=32 |url=https://books.google.com/books?id=vEhYAAAAMAAJ |language=en}}</ref><ref name=mich>{{cite book |title=The Michigan Technic |date=February 1958 |publisher=University of Michigan, College of Engineering |page=1 |url=https://books.google.com/books?id=AUjiAAAAMAAJ |language=en}}</ref><ref>{{cite book |title=Chemical & Process Engineering |date=1952 |publisher=L. Hill Technical Group. |page=32 |url=https://books.google.com/books?id=LO8rAQAAMAAJ |language=en}}</ref>  The product found early use as a food wrap, its very low oxygen permeability helping to keep foods fresh.<ref name=pm>{{cite book |title=Popular Mechanics |date=October 1949 |publisher=Hearst Magazines |page=174 |url=https://books.google.com/books?id=D9kDAAAAMBAJ |language=en}}</ref><ref name=illini>{{cite book |title=Illini Horticulture |date=1937 |publisher=Illinois State Horticultural Society |url=https://books.google.com/books?id=At5NAAAAYAAJ |language=en}}</ref><ref name=modern>{{cite book |title=Modern Packaging Encyclopedia |date=1971 |publisher=McGraw-Hill |page=135 |url=https://books.google.com/books?id=kcJPAAAAYAAJ |language=en}}</ref>  Its clinginess and better stability at a range of humidities was an advantage over the cellulose wrapping films used previously; Pliofilm became about as popular as [[Cellophane]] by 1937 and had supplanted cellulose films by 1942.<ref name=illini/><ref name=modern/><ref>{{cite book |title=Plastics in Industry |date=1942 |publisher=Chapman & Hall Limited |pages=204–5 |url=https://books.google.com/books?id=3jsFAAAAMAAJ |language=en}}</ref>  Pliofilm could also function as a [[shrink wrap]] and was marketed as a means to reseal bottles (it was advised to place the Pliofilm over an [[embroidery hoop]] and to heat it while twisting the bottle).<ref name=pm/><ref>{{cite book |title=Decisions of Commissioner of Patents and U.S. Courts in Patent and Trademark and Copyright Cases |date=1945 |publisher=U.S. Government Printing Office |page=207 |url=https://books.google.com/books?id=ZAizAAAAMAAJ |language=en}}</ref>
The material was also used to manufacture aprons and protective sleeves to protect factory workers from hazardous substances.<ref name=phr/>  Pliofilm saw widespread use during [[World War II]] as a means of protecting tools and engines during shipping.<ref name=mich/>  For aviation parts a modified product was produced; a chemical known as RMF was added in quantities of 1–5% to make the product less susceptible to deterioration by [[ultra-violet light]].<ref name=phr/><ref name=phr2/>  RMF led to dermatitis in workers who had contact with it.  The [[United States Public Health Service]] investigated the factories involved and recommended that workers wear protective sleeves made from ordinary Pliofilm.<ref name=phr/>  The manufacturing process also caused workers to become exposed to benzene.  A study of Pliofilm workers at Goodyear's [[Akron, Ohio|Akron]] and [[St. Marys, Ohio]], plants between 1936 and 1976 was used as the basis for determining the [[cancer slope factor]] and occupational exposure standards for benzene.<ref>{{cite journal |last1=Williams |first1=Pamela R. D. |last2=Paustenbach |first2=Dennis J. |title=Reconstruction of benzene exposure for the Pliofilm cohort (1936–1976) using Monte Carlo techniques |journal=Journal of Toxicology and Environmental Health. Part A |date=April 25, 2003 |volume=66 |issue=8 |pages=677–781 |doi=10.1080/15287390306379 |pmid=12746133 |s2cid=27528269 |url=https://pubmed.ncbi.nlm.nih.gov/12746133/ |issn=1528-7394}}</ref>
The [[United States Armed Forces]] used Pliofilm to waterproof firearms during World War II [[amphibious warfare|amphibious landings]]. Sleeves were produced in three sizes to suit pistols, rifles, and sub-machine guns and were sealed by tying a knot in the sleeve or with an [[rubber band|elastic band]].<ref name=hambucken>{{cite book |last1=Hambucken |first1=Denis |title=American Soldier of WWII: D-Day, A Visual Reference |date=2013 |publisher=The Countryman Press |isbn=978-1-58157-200-1 |page=39 |url=https://books.google.com/books?id=Qdi4AQAAQBAJ |language=en}}</ref> It was intended that soldiers would tear off the sleeve after landing, though some troops kept them on inland due to fields having been flooded by the Germans as a defensive measure. The Pliofilm usually trapped enough air to keep the firearm buoyant if dropped in water. Because the sleeve prevented use of the weapon's regular sling some troops fashioned ad-hoc slings from rope that could be used over the Pliofilm.<ref name=hambucken/><ref name=marriott>{{cite book |last1=Marriott |first1=Leo |last2=Forty |first2=Simon |title=The Normandy Battlefields: D-Day and the Bridgehead |date=2014 |publisher=Casemate Publishers |isbn=978-1-61200-338-2 |page=94 |url=https://books.google.com/books?id=Q6e6DQAAQBAJ |language=en}}</ref><ref>{{cite book |last1=Morgan |first1=Martin |title=The Americans on D-Day: A Photographic History of the Normandy Invasion |date=2014 |publisher=Zenith Press |isbn=978-1-62788-154-8 |page=141 |url=https://books.google.com/books?id=Y68oAwAAQBAJ}}</ref> The ''[[Houston Chronicle]]'' series "D-Day In Color" noted that Pliofilm wrapped around weaponry is evident in an image of [[United States Army]] infantry at the [[Normandy landings]].<ref>{{cite news |last1=Ramirez |first1=Fernando |title=D-day in color |url=https://www.chron.com/national/slideshow/D-day-in-color-146202.php |access-date=February 14, 2021 |work=Houston Chronicle |date=June 6, 2017}}</ref>
Pliofilm manufacture was hindered by the Japanese occupation of rubber-producing countries in Southeast Asia.<ref>{{cite book |title=Modern Packaging |date=1945 |publisher=Morgan-Grampian Publishing Company |page=116 |url=https://books.google.com/books?id=3gglAAAAMAAJ |language=en}}</ref>  Commercial outputs were stopped and the entire production given over to military uses, leading to a large commercial demand and a backlog of orders after the war's end.<ref>{{cite book |title=Food Manufacture |date=1945 |publisher=Morgan-Grampian |page=191|url=https://books.google.com/books?id=UF0eAQAAIAAJ |language=en}}</ref><ref>{{cite book |title=Modern Packaging |date=1945 |publisher=Morgan-Grampian Publishing Company |page=117 |url=https://books.google.com/books?id=3gglAAAAMAAJ |language=en}}</ref>  In the post-war years Pliofilm saw use as a food wrap, to package drugs and textiles, and as a means of laminating paper.<ref name=mich/><ref name=stern>{{cite book |last1=Stern |first1=Harold Jacob |title=Rubber: Natural and Synthetic |date=1967 |publisher=Maclaren |page=59 |url=https://books.google.com/books?id=WOlGAQAAIAAJ |language=en}}</ref> It was also marketed as Vitafilm.<ref name=stern/>  Production was extended abroad to the Goodyear factory in [[Wolverhampton]], England, in the late 1940s.<ref>{{cite book |title=Food Manufacture |date=1949 |page=169 |url=https://books.google.com/books?id=5mEeAQAAIAAJ |language=en}}</ref> The [[United States Mint]] switched its packaging for [[mint set]] coins from Cellophane to Pliofilm in 1955.<ref>{{cite book |last1=Herbert |first1=Alan |title=Coin Clinic – 1,001 Frequently Asked Questions |date=1995 |publisher=Krause Publications |isbn=978-0-87341-380-0 |page=163 |url=https://books.google.com/books?id=gkyVAgvBGN4C |language=en}}</ref> The [[American Chemical Society]] awarded Harold J. Osterhof the 1971 [[Charles Goodyear Medal]] for inventing Pliofilm.<ref name=alumnus/>  It remained commercially available in 1987.<ref name=stepek/>
== References ==
{{Reflist}}
[[Category:Packaging materials]]
[[Category:Food storage]]
[[Category:Transparent materials]]
[[Category:Organic polymers]]
[[Category:Rubber]]