Epoxy value
{{Short description|Measure of the epoxy content of a substance}}
Epoxy value derives from the Epoxy equivalent weight (EEW) or Weight Per Epoxide (WPE) and is a measure of the epoxy content of an epoxy resin or epoxy reactive diluent, or glycidyl ether.{{Cite book|last=Howarth|first=G.A|title=Waterborne Maintenance Systems for Concrete and Metal Structures|publisher=The Royal Society of Chemistry|year=1995|isbn=0-85404-740-9|editor-last=Karsa|editor-first=D.R|volume=165|location=Cambridge, U.K|chapter=5|editor-last2=Davies|editor-first2=W.D}} This is an important parameter as it allows determination of the correct mix ratio of an epoxy system with a curing agent.{{Cite web|title=How do you know how much hardener to mix with how much resin?:Ask the Doctor|url=http://www.mereco.com/resources/ask-the-doctor/hardener-to-resin-ratio|access-date=2021-08-01|website=www.mereco.com|archive-date=2022-09-13|archive-url=https://web.archive.org/web/20220913075415/http://www.mereco.com/resources/ask-the-doctor/hardener-to-resin-ratio|url-status=dead}} The epoxide equivalent weight is usually measured first and done by titration. The standard test method is ASTM D1652 though this has been modified by certain states of the USA.{{Cite web|title=Determining Epoxide Equivalent and Amine Value of Resins|url=https://ftp.dot.state.tx.us/pub/txdot-info/cst/TMS/800-B_series/pdfs/ctm815.pdf|website=Texas.gov}} The epoxy equivalent weight (EEW) maybe defined as: the number of grams of epoxy resin required to give 1 mole of epoxy groups.{{Cite book|last=Spyrou|first=Emmanouil|url=https://www.worldcat.org/oclc/828194496|title=Powder coatings chemistry and technology|date=2012|isbn=978-3-86630-884-8|page=129|location=Hanover|oclc=828194496}} The epoxy value is defined as the number of moles of epoxy group per 100g resin.Howarth, GA. Master of Science thesis "The synthesis of a legislation compliant corrosion protection paint system, based on waterborne epoxy, urethane and oxazolidine technology". April 1997 Imperial College London Chapter 2.1.1 page 32
Example calculations
Polyoxypropylene diglycidyl ether, a reactive diluent with the trade name of Diluent F, has an average molecular weight of 1000 and a functionality of 2 so the EEW is 1000/2 = 500. The epoxy value is defined as the number of moles of epoxy group per 100g resin. So as an example using an epoxy resin with molar mass of 382 and that has 2 moles of epoxy groups per mole of resin, the EEW = 382/2 = 191, and the epoxy value is calculated as follows: 100/191 = 0.53 (i.e. the epoxy value of the resin is 0.53).{{Cite book|last=Müller|first=Bodo|url=https://www.worldcat.org/oclc/76886114|title=Coatings formulation : an international textbook|date=2006|publisher=Vincentz|others=Urlich Poth|isbn=3-87870-177-2|page=111|location=Hannover|oclc=76886114}}
Alternative techniques
There are methods using instruments that do not use traditional titration techniques to determine epoxide equivalent weights.{{Citation |last1=MONIZ |first1=W. B. |title=Epoxide Equivalent Weight Determination by Carbon-13 Nuclear Magnetic Resonance |date=1979-12-03 |url=https://doi.org/10.1021/bk-1979-0114.ch007 |work=Epoxy Resin Chemistry |volume=114 |pages=83–90 |series=ACS Symposium Series |publisher=AMERICAN CHEMICAL SOCIETY |doi=10.1021/bk-1979-0114.ch007 |isbn=978-0-8412-0525-3 |access-date=2022-03-23 |last2=PORANSKI |first2=C. F.|url-access=subscription }}
References
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Further reading
- {{Cite web|title=Amines {{!}} Introduction to Chemistry|url=https://courses.lumenlearning.com/introchem/chapter/amines/#:~:text=The%20amine%20functional%20group%20contains,by%20a%20carbon-containing%20substituent.&text=Amine%20groups%20bonded%20to%20an,are%20known%20as%20aromatic%20amines.|access-date=2021-07-22|website=courses.lumenlearning.com}}
- {{Cite book|url=https://www.worldcat.org/oclc/182890|title=Epoxy resin technology.|date=1968|publisher=Interscience Publishers|others=Paul F. Bruins, Polytechnic Institute of Brooklyn|isbn=0-470-11390-1|location=New York|oclc=182890}}
- {{Cite book|last=Flick|first=Ernest W.|url=https://www.worldcat.org/oclc/915134542|title=Epoxy resins, curing agents, compounds, and modifiers : an industrial guide|date=1993|isbn=978-0-8155-1708-5|location=Park Ridge, NJ|oclc=915134542}}
- {{Cite book|last=Lee|first=Henry|url=https://www.worldcat.org/oclc/311631322|title=Handbook of epoxy resins|date=1967|publisher=McGraw-Hill|others=Kris Neville|isbn=0-07-036997-6|edition=[2nd, expanded work]|location=New York|oclc=311631322}}
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