Jump to main content
Jump to site search

Issue 43, 2014
Previous Article Next Article

Novel gigahertz frequency dielectric relaxations in chitosan films

Author affiliations


Molecular relaxations of chitosan films have been investigated in the wide frequency range of 0.1 to 3 × 109 Hz from −10 °C to 110 °C using dielectric spectroscopy. For the first time, two high-frequency relaxation processes (in the range 108 to 3 × 109 Hz) are reported in addition to the low frequency relaxations α and β. These two relaxation processes are related to the vibrations of OH and NH2/NH3+, respectively. The high-frequency relaxations exhibit Arrhenius-type dependencies in the temperature range 10 °C to 54 °C with negative activation energy; this observation is traceable to hydrogen bonding reorientation. At temperatures above the glass transition temperature (54 °C), the activation energy changes from negative to positive values due to breaking of hydrogen bonding and water loss. Upon cooling in a sealed environment, the activation energies of two relaxation processes are nearly zero. FTIR and XRD analyses reveal associated structural changes upon heating and cooling. These two new high-frequency relaxation processes can be attributed to the interaction of bound water with OH and NH2/NH3+, respectively. A plausible scenario for these high-frequency relaxations is discussed in light of impedance spectroscopy, TGA, FTIR and XRD measurements.

Graphical abstract: Novel gigahertz frequency dielectric relaxations in chitosan films

Back to tab navigation

Publication details

The article was received on 14 Aug 2014, accepted on 29 Aug 2014 and first published on 29 Aug 2014

Article type: Paper
DOI: 10.1039/C4SM01804D
Author version
Download author version (PDF)
Citation: Soft Matter, 2014,10, 8673-8684

  •   Request permissions

    Novel gigahertz frequency dielectric relaxations in chitosan films

    S. Kumar-Krishnan, E. Prokhorov, M. Ramírez, M. A. Hernandez-Landaverde, D. G. Zarate-Triviño, Y. Kovalenko, I. C. Sanchez, J. Méndez-Nonell and G. Luna-Bárcenas, Soft Matter, 2014, 10, 8673
    DOI: 10.1039/C4SM01804D

Search articles by author