D.s.c. investigation of the states of water in poly(vinyl alcohol) membranes

Akon Higuchi, Toshiro Iijima

Research output: Contribution to journalArticlepeer-review

165 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)1207-1211
Number of pages5
JournalPolymer
Volume26
Issue number8
DOIs
StatePublished - Aug 1985

Keywords

  • differential scanning calorimetry
  • heat capacity
  • membrane
  • poly(vinyl alcohol)
  • water

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