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Study of the Molecular Mobility of Polysaccharide Solid Thin Layers by Dielectric Relaxation Spectroscopy

Published online by Cambridge University Press:  10 February 2011

K. Liedermann ,
L. Lapčík Jr  and
S. Desmedt
K. Liedermann
Affiliation:
Department of Physics, Faculty of Electrical Engineering and Computer Science, Technical University of Brno, Technicka 8, CZ -616 00 Brno, Czech Republic, liederm@dphys.fee.vutbr.cz
L. Lapčík Jr
Affiliation:
Department of Physics and Material Science, Faculty of Technology in Zlín, Technical University of Brno, nám. TGM 275, CZ-762 72 Zlín, Czech Republic, lapcik@zlin.vutbr.cz
S. Desmedt
Affiliation:
Laboratory of General Biochemistry and Physical Pharmacy, Faculty of Pharmaceutical Sciences, University of Gent, Harelbekestraat 72, B-9000 Gent, Belgium, Stefaan.Desmedt@rug.ac.be.
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Abstract

Temperature dependence of measured dielectric relaxation spectra (DRS) in the frequency range 20 Hz - 1 MHz of hydroxyethylcellulose (HEC) are in the temperature range 100 – 350 K. of Arrhenius character with one relaxation process at 150 – 250 K. This process reflects most probably β-relaxation of the side chain groups. Calculated activation energy of this process was 5730 kJ/mole. Four types of polysaccharides were studied at 293 K temperature: hyaluronic acid (HA), chondroitin sulfate (CHS), HEC and carboxymethylcellulose (CMC), in the low-frequency range 10−5 - 100 Hz. Measured dielectric spectra were interpreted as sum of one A.C. conductivity process and of up to two relaxation processes. The relaxation processes were described by means of the Havriliak-Negami formula and their parameters were related to the molecular structure of the polymers. The low value of a in CHS is related to its strong coupling due to the presence of two polar groups in its monomeric unit, whereas low values of α × β are interpreted as being due to the strong steric hindrances caused by long pendants present in HEC.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 500: Symposium EE – Electrically Based Microstructural Characterization II , 1997 , 157
Copyright
Copyright © Materials Research Society 1998

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References

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