D.s.c. analysis shows that heat absorbed in the heating process of water in poly(vinyl alcohol) membranes is higher than that evolved in the cooling process. A remarkable discrepancy is found between these heats when the water retention, H, of the membrane is lower than 0.5 g H2O/g swollen membrane. The amounts of freezable water in the membranes were estimated by use of the relation observed between the temperature and the enthalpy of the crystallization of super-cooled water. The amounts estimated from the heats absorbed or evolved agree within 2% when H was above 0.6. When H is below 0.5, however, the ratio of these two amounts was greater than 2. This difference is explained by the heat capacity of the water below 250 K increasing anomalously compared with that of bulk water. © 1985.
CITATION STYLE
Higuchi, A., & Iijima, T. (1985). D.s.c. investigation of the states of water in poly(vinyl alcohol) membranes. Polymer, 26(8), 1207–1211. https://doi.org/10.1016/0032-3861(85)90254-X
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