Bound Water Content of Polymers Determined by TG

The mass of water, mass of dry sample, temperature of dehydration and rate of dehydration can be evaluated by TG. When TG-DTA is applied to water-sorbing samples, the heat of vaporization is simultaneously evaluated. For these measurements, an aluminum open-type crucible without a lid is usually used (see Section 2.2.1). The gas flow-rate markedly influences this type of measurement. Mass loss starts immediately after the water-sorbed sample is placed on the TG sample holder. The sample 

When water molecules co-exist with samples without any intermolecular interaction, the mass loss(TG) and vaporization peak (DTA) terminate at a temperature lower than 100 °C. In contrast, when water is tightly attached to polymers, mass loss is observed in two stages or multiple stages. Even if mass loss is observed in one stage on the TG curves, two or more peaks may be observed if the DTG curve (dni/dT) is deconvo-luted. DTA endotherms due to vaporization also show multiple peaks. 

---