کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1484856 | 1510531 | 2007 | 5 صفحه PDF | دانلود رایگان |

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.
Journal: Journal of Non-Crystalline Solids - Volume 353, Issues 47–51, 1 December 2007, Pages 4523–4527