Article ID Journal Published Year Pages File Type
1484856 Journal of Non-Crystalline Solids 2007 5 Pages PDF
Abstract

We report on the dielectric and calorimetric results of water solutions of poly(vinyl methyl ether) (PVME), poly(vinyl pyrrolidone) (PVP), pentaethylene glycol (5EG) and tri-poly(propylene glycol) (3PG) for a temperature range of 130 K up to crystallization. For 3PG and 5EG two relaxation processes (Process I and II) were observed for all the hydration levels whereas for PVME and PVP a single peak was detected (Process II). We will show that the temperature dependence of the relaxation time of Process II, related to water molecules dynamics, presents a crossover at a temperature about the calorimetric glass transition of the whole system. We show that this crossover could be interpreted in terms of confinement effects due to the frozen-in of the whole solution. Finally, in spite of the fact that water molecules are surrounded by different environments, the results are very similar for the all the investigated systems, which suggest a general behavior for confined water. From this finding, we have obtained an intrinsic value of the activation energy for water dynamics in confining environments.

Related Topics
Physical Sciences and Engineering Materials Science Ceramics and Composites
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