Dielectric study of aqueous solutions and solid samples of methylcellulose
The dielectric properties of aqueous solutions and hydrated solid samples of methylcellulose were studied by means of the thermally stimulated depolarization current (TSDC) method in the temperature range 77–300 K and over a wide range of concentrations, 0.025–2.0 gr/lt, and water contents, 1.8–34.9%. Two water-dependent complex dispersions were observed in the range of 77–155 K (low-temperature dispersion) and 155–300K (high-temperature dispersion). The high-temperature dispersion was studied in detail. In the solutions the dispersion is due to thermal release of space charges trapped at the boundaries of the crystallites of the polycrstalline samples. In the solid samples three mechanisms contribute to the dispersion: water-assisted relaxation of local polar groups, space charge polarization connected with dc conductivity and accumulation of space charges at the electrodes. The results allow us to determine the critical water content for the completion of the primary hydration layer to 7–8 %.
Key wordsDielectric relaxation hydration properties depolarization current space charges
Unable to display preview. Download preview PDF.
- 2.Bordi F, Cametti C (1985) Ber Bunsenges Phys Chem 89:747Google Scholar
- 3.Algie JE (1979) Dielectric Properties of Keratin and Cellulose; in: Happey F (ed) Applied Fibre Science. vol 2, Academic, New York, pp 169–203Google Scholar
- 4.van Turnhout J (1980) Thermally Stimulated Discharge of Electrets; in: Sessler GM (ed) Electrets. Springer, Berlin, pp 81–215Google Scholar
- 7.Pissis P, Anagnostopoulou-Konsta A (1985) In: Sessler GM, Gerhard-Multhaupt R (eds) Proceedings of the 5th International Symposium on Electrets, Heidelberg, IEEE Service Center, Piscataway, pp 842–847Google Scholar
- 10.Seymour RW, Weinhold S, Haynes SK (1979) J Macromol Sci Phys B16:337Google Scholar