Abstract
The mobility of water molecules existing in polyamide 6- and epoxy-carbon fiber model composites was discussed in comparison with that in each neat polymer specimen. The water mobility was evaluated by a differential scanning calorimetry (DSC), under the process of which the watercontaining specimens weresubjected to cooling from 25°C to -70°C and subsequent reversed heating to 25°C at 2°C/min, and a freezing (crystallization) and a melting behavior of water were analyzed. The absorbed water in PA6 exists as a non-freezing bound water, probably due to the strong interaction with amide group, while in the composite specimen a freezable bound water and a water with greater mobility like a free water are clearly detected. The water in EP resin mainly behaves as a freezable bound water, and the introducing the carbon fibers results in an increase in the mobility nearly equal to the free water. These DSC results suggest that for the model composites there exist some heterogeneous region and/or defects accumelated under very weak interaction with the water molecules.
