EFFECT OF PHOTODEGRADATION ON WETTABILITY AND WATER SORPTION ISOTHERM OF AN AMINE-CURED EPOXY

摘要

The effects of photodegradation resulting from outdoor aging on wettability and water sorption isotherm of amine-cured epoxies have been studied. Substantial photochemical changes have occurred, with formation of oxidation products as well as loss of materials. The increase in polar wetting properties due to aging follows closely with an increase in the concentration of the oxidized products. The sorption isotherms of specimens before and after outdoor aging for various times follow a Type n sorption, but the high RH upward curvatures become more pronounced for aged specimens. The equilibrium moisture contents decrease in the early stages of aging but this trend is reversed at late aging times. Except for the severely-degraded specimens, the number of adsorbed water layer increases with photo-oxidation level. The Guggenheim-Anderson-de Boer model is suitable for describing moisture soiption isotherms of amine-cured epoxies undergoing photodegradation.