State of water in void

Abstract The effect of voids on the state of water absorbed in epoxy has been examined using differential scanning calorimetric analysis for a range of void contents (0 to 50%). For void-free specimens, water absorbed is classified as bound water (nonfreezing). Analysis of the medium and high void content specimens revealed water absorbed in three states: free water, freezable bound water, and nonfreezable bound water. The differential scanning calorimetric results show that the proportions of free water and freezable bound water increase with increasing void content, while the content of nonfreezable bound water decreased. Moisture-induced swelling decreased with increasing void content. The swelling is attributed to the content of nonfreezable bound water as determined by differential scanning calorimetric analysis