Interaction of epoxy resins with water: the depression of glass transition temperature

The depression of T_g in a number of epoxy-water systems has been investigated calorimetrically. Except where an unbalanced reaction stoichiometry was used, experimental results are in good agreement with theoretical predictions based on equations developed for the composition dependent T_g in polymer diluent-systems. Thermal analysis also demonstrates a complex thermal behaviour on rescanning of samples, attributed to diluent diffusing out of the sample. The importance of this behaviour in the context of solvent-induced physical ageing of epoxy resin composites is discussed.