The anomalous lowering of the glass transition of an epoxy resin by plasticization with water

The validity of the assertion that 6 to 7 wt% absorbed water lowers the glass transition, T sub(g), ( similar to 250 degree C) of a highly cross-linked, high temperature epoxy resin (NARMCO 5208) by 100 to 150 degree C was investigated. No glass transition could be observed by differential scanning calorimetry and the thermal mechanical analyzer gave inconclusive results. The dynamic mechanical analyzer gave a clear indication of a glass-like transition at about 250 degree C which was reversible, reappearing upon cooling and reheating.