|MadSci Network: Chemistry|
Thanks for your question. Ethylene glycol is a 2 carbon diol. That means it contains a hydroxy group bonded to a two methylene unit which is bonded to another hydroxy group. The structure is:
H H | | HO--C--C--OH | | H H
It is a viscous colorless liquid. If you are interested in its physical and chemical properties as a pure substance that information can be found in the CRC Handbook of Chemistry and Physics (any recent edition).
The use of ethylene glycol itself in the production of adhesives seems to be limited to two major roles. The first is as a solvent or additive. [Whittington's Dictionary of Plastics, J. F. Carley, Technonic Pub; 1993] Adhesives are generally composed of mixtures of polymers (long chain molecules) that possess functional groups that adhere to surfaces. These mixtures are sometimes dissolved in a suitable solvent chosen to impart a desired property to the adhesive. Ethylene glycol is used as a solvent for cellulosic polymers (carbohydrate based) and cellophane in particular. As an additive, its hygroscopicity (fondness for water) results in a softness and flexibility to the resulting glue. It is an additive in cork and tobacco products for this same reason. [Encyclopedia of Polymer Science and Technology, vol I, pg 586, H.F. Mark et.al. , John Wiley and Sons; 1964]. The second major role is as a monomer intermediate in the synthesis of a class of polymeric additives known as plasticizers. [Mark] There is a tremendous variety of these polymers which are added to adhesives and plastics to increase the flexibility of the material. Examples of these are poly(ethylene glycol) and poly(ethylene terephthalate) . Besides plasticizers, derivatives of ethylene glycol are used as solvents as well. "Cellusolve" is the mono-methyl ether of ethylene glycol. That means one of the hydroxy groups has a methyl group attached instead of a hydrogen. [Handbook of Adhesives, 2nd ed., I. Skeist, Van Nostrand Reinhold inc.; 1977] There is a wide selection of ethylene glycol based solvent derivatives composed of substituted cellusolves as well as doubly substituted ethylene glycol derivatives. These are mentioned in the Skeist reference [Skeist, pg 894] and the Carley reference [Carley, pg 169-171]. An extensive article on the uses of poly-ols (including ethylene glycol) in polymers and adhesives appears in the Mark reference. [Mark, pg 586, vol I] Ethylene glycol based plasticizers are mentioned in the Mark reference and in a Kroschwitz reference. [Concise Encyclopedia of Polymer Science and Engineering, J. I. Kroschwitz, pg. 799, John Wiley and Sons; 1990] The structures of poly(ethylene terephthalate) and other polyether-ester polymers appear in the Kroschwitz article.
I hope this information was useful.
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