Ethylene vinyl alcohol: Difference between revisions
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Revision as of 20:59, 1 March 2013
Ethylene vinyl alcohol (EVOH) is a formal copolymer of ethylene and vinyl alcohol. Because the latter monomer mainly exists as its tautomer acetaldehyde, the copolymer is prepared by polymerization of ethylene and vinyl acetate to give the ethylene vinyl acetate (EVA) copolymer followed by hydrolysis. The plastic resin is commonly used in food applications, and it has lately found application in plastic gasoline tanks for automobiles. Its primary purpose is to provide barrier properties, primarily as an oxygen barrier for improved food packaging shelf life and as a hydrocarbon barrier for fuel tanks. EVOH is typically coextruded or laminated as a thin layer between cardboard, foil, or other plastics. EVOH copolymer is defined by the mole % ethylene content: lower ethylene content grades have higher barrier properties; higher ethylene content grades have lower temperatures for extrusion.
Industrial production
Kuraray produces EVOH resin under the name "EVAL," with 10,000 ton plant in Okayama, Japan; a 35,000 ton plant in the U.S. (near Houston, TX) under its subsidiary Kuraray America; and a 24,000 ton plant in Belgium under its subsidiary EVAL Europe.[1]
Nippon Gohsei has three production sites in Japan, US and Europe. In 2004, Nippon Gohsei started production at its Hull, UK, site having the world's largest single line capacity.[2] It is sold under the trade name SoarnoL.
Use in medical applications
EVOH is used in a liquid embolic system in interventional radiology, e.g. in Onyx.[3] Dissolved in dimethyl sulfoxide (DMSO) and mixed with a radiopaque substance, ethylene vinyl alcohol copolymer is used to embolize blood vessels.
References
- ^ http://www.kuraray.co.jp/en/company/business/eval.html
- ^ Nippon Gohsei – The right strategy to get the results www.csr4u.co.uk.
- ^ Embolization of Intracranial Arteriovenous Malformations with Ethylene-Vinyl Alcohol Copolymer (Onyx). American Journal of Neuroradiology 30:99-106, January 2009.