styrofoam
{{Short description|Trademarked brand for extruded polystyrene}}
{{about|the Styrofoam brand|other materials sometimes referred to as "Styrofoam"|extruded polystyrene foam|and|expanded polystyrene|other uses|Styrofoam (disambiguation)}}
Styrofoam is a brand of closed-cell extruded polystyrene foam (XPS), manufactured to provide continuous building insulation board used in walls, roofs, and foundations as thermal insulation and as a water barrier. This material is light blue in color and is owned and manufactured by DuPont. DuPont also has produced a line of green and white foam shapes for use in crafts and floral arrangements.{{cite web|url=http://craft.dow.com/craft/about/cup.htm|archive-url=https://web.archive.org/web/20051201163706/http://craft.dow.com/craft/about/cup.htm|title=You can't drink coffee from a STYROFOAM cup.|archive-date=2005-12-01|publisher=The Dow Chemical Company}}
The term styrofoam has become a genericized trademark; it is often used in the United States as a colloquial term to refer to expanded (not extruded) polystyrene foam (EPS).{{cite web |url= https://www.genericides.org/trademark/styrofoam|title= Has styrofoam become a generic trademark? |access-date= April 29, 2021 |website= genericides.org |date= 31 January 2020 }} Outside the United States, EPS is most commonly referred to as simply "polystyrene" with the term "styrofoam" being used in its capacity to describe all forms of extruded polystyrene, not just the Dupont brand itself. Polystyrene (EPS) is often used in food containers, coffee cups, and as cushioning material in packaging.{{Cite web |date=March 24, 2008 |title=What is STYROFOAM? |url=http://building.dow.com/styrofoam/what.htm |archive-url=https://web.archive.org/web/20080324134328/http://building.dow.com/styrofoam/what.htm |archive-date=2008-03-24}} Styrofoam is, however, a far less dense material than EPS and is more commonly suited to tasks such as thermal insulation.
Additionally, it is moderately soluble in many organic solvents, cyanoacrylate, and the propellants and solvents of spray paint.
History
In the 1940s, researchers, originally at Dow's Chemical Physics Lab, led by Ray McIntire, found a way to make foamed polystyrene. They rediscovered a method first used by Swedish inventor Carl Georg Munters, and obtained an exclusive license to Munters's patent in the United States.{{cite book
| last = Boundy
| first = Ray H.
|author2=Amos, J. Lawrence
| title = A History of the Dow Chemical Physics Lab
| publisher = Marcel Dekker, Inc.
| year = 1991
| location = New York
| pages = 117–128
| isbn = 0-8247-8097-3}} Dow found ways to adapt Munters's method to make large quantities of extruded polystyrene as a closed cell foam that resists moisture. The patent on this adaptation was filed in 1947.{{cite patent |country=US |number=2450436 |status= |title=Manufacture of cellular thermoplastic products |pubdate=1948-10-05 |gdate=1948-10-05 |fdate=1947-07-26 |pridate= |inventor=Otis Ray McIntire |invent1= |invent2= |assign1= |assign2= |class= |url=}}
Uses
Styrofoam has a variety of uses. Styrofoam is composed of 98% air, making it lightweight and buoyant.{{cite web| url= http://www.forte-eps-solutions.com/styrofoam-sheets-polystyrene-insulation-difference-new-jersey-new-york-ontario-quebec.html|title= What is the Difference between EPS Polystyrene and (styrofoam)?}}
DuPont produces Styrofoam building materials, including varieties of building insulation sheathing and pipe insulation. The claimed R-value of Styrofoam insulation is approximately 5 °F⋅ft2⋅h/BTU for 1 inch thick sheet.{{Cite web |title=Dow Announces New Technology for STYROFOAM Insulation |url=http://building.dow.com/media/news/2007/20071205a.htm |archive-url=https://web.archive.org/web/20110812230057/http://building.dow.com/media/news/2007/20071205a.htm |archive-date=2011-08-12}}
Styrofoam can be used under roads and other structures to prevent soil disturbances due to freezing and thawing.{{cite web|url=http://building.dow.com/na/en/applications/geotech/index.htm|title=Geotechnical applications of Styrofoam|publisher = Dow Chemical| access-date=2009-10-28}}{{cite web|url=http://www.alaskool.org/resources/regional/nw_reg_pro/permafrost.html|title=Engineering considerations when building on permafrost|access-date=2007-08-30}}
DuPont also produces Styrofoam blocks and other shapes for use by florists and in craft products.{{cite web|url=http://craft.dow.com|title=STYROFOAM Brand Foam Crafts| access-date=2010-12-31}} DuPont insulation Styrofoam has a distinctive blue color; Styrofoam for craft applications is available in white and green.
Environmental issues
The EPA and International Agency for Research on Cancer reported limited evidence that styrene is carcinogenic for humans and experimental animals, meaning that there is a positive association between exposure and cancer and that causality is credible, but that other explanations cannot be confidently excluded.{{cite web
|title = (Styrene) Fact Sheet: Support Document (CAS No. 100-42-5)
|url = http://www.epa.gov/chemfact/styre-sd.pdf |date = December 1994
|archive-url = https://web.archive.org/web/20150924043958/http://www.epa.gov/chemfact/styre-sd.pdf |archive-date= 24 September 2015 |access-date = 8 January 2020
|website = EPA
}}
|title = STYRENE (Group 2B)
|url = http://www.inchem.org/documents/iarc/vol82/82-07.html |year = 2002 |access-date = 8 January 2020
|website = INCHEM
}}
See also the expansive list of environmental issues of polystyrene, among which it being non-biodegradable.