Influence of stoichiometric ratio on water absorption in epoxy resins

✍ Scribed by Christian Grave; Iain McEwan; Richard A. Pethrick

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 222 KB
• Volume: 69
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19980919)69:12<2369::aid-app8>3.0.co;2-6

✦ Synopsis

Dielectric, gravimetric, dynamic mechanical, and infrared measurements are reported on the effect of different stoichiometric ratios on the water absorption of diglycidyl ether of bisphenol A (DGEBA), MY720 (Ciba Geigy) cured with stoichiometric variations of triethylenetetramine (TETA), (BDH). Resin samples were prepared with stoichiometric ratios of epoxy:amine from 3 : 1 through 1 : 1 to 1 : 3. Analysis of the water absorption characteristics of these materials showed the existence of water in two different environments; molecules bound to specific sites in the matrix and clustered in microvoids as ''free water.'' Diffusion coefficients and equilibrium water uptake were shown to markedly increase with an increase in the amine ratio. An anomaly observed in dielectric results is attributed to a high rate of diffusion in the high amine ratio materials.