The Influence of Moisture Absorption into Uncured Resins.

Patrick Polak


Epoxy resin has a wide variety of engineering applications, including within the aerospace industry. Moisture absorption has been shown to have a number of negative effects on the properties of epoxy and, although significant research has been conducted on moisture absorption into the cured product, little work has been carried out on absorption into the uncured resin. This is considered for both the resin and the hardener in three parts here; the rate of moisture absorption, the effect on the temperature profile of the resin/hardener reaction and the volumetric expansion of the product, and the effect of moisture absorption on the mechanical properties of the cured resin. Significant moisture absorption was observed in the hardening agent as well as the epoxy resin, although the absorption rate and maximum saturation of the hardener was much higher. The absorbed moisture was shown to cause substantial volumetric expansion during reaction and a notable loss in tensile, compressive and shear strength. Small but distinguishable effects on the temperature profile were also observed. These findings represent a useful basis for future research and the compilation of practical guidelines for the storage and use of epoxy in industry.

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