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Issue Eur. Phys. J. Appl. Phys.
Volume 46, Number 2, May 2009
Article Number 20405
Number of page(s) 10
Section Physics of Organic Materials and Devices
DOI 10.1051/epjap/2009048
Published online 03 April 2009

Eur. Phys. J. Appl. Phys. 46, 20405 (2009)
DOI: 10.1051/epjap/2009048

Dielectric and rheological properties of polyaniline organic dispersions

N. Bohli1, 2, A. Belhadj Mohamed1, V. Vignéras-Lefèbvre2 and J.-L. Miane2

1  Laboratoire de Nanomatériaux et des Systèmes pour l'Énergie, Centre de Recherches et de Technologies de l'Énergie, Technopole de Borj Cedria, BP 95, 2050 Hammam Lif, Tunisia
2  Laboratoire de l'Intégration du Matériau au Système, UMR CNRS 5218, ENSCPB, 16 av. Pey Berland, 33607 Pessac, France

nadra.bohli@crten.rnrt.tn

Received: 13 September 2008 / Received in final form: 23 December 2008 / Accepted: 12 February 2009 / Published online: 3 April 2009

Abstract
This paper reports the examination of the evolution of polyaniline-organic solvent interactions in the temperature range of 294–353 K. For this purpose, rheological and dielectric investigations have been undertaken for dispersions of plast-doped polyaniline in two different solvents (dichloroacetic acid and formic acid/dichloroacetic acid mixture). Dielectric permittivity has been investigated using the open ended coaxial line method in the frequency range of [100 MHz, 10 GHz]. Dielectric loss spectra of both dispersions showed a relaxation peak which was well fitted by Havriliak-Negami function. The relaxation was attributed to a Maxwell Wagner Sillars relaxation within polyaniline clusters. The difference found between relaxation parameters of the pure solvent and polyaniline dispersions was attributed to the solvent/polyaniline interactions. The relaxation time relative to the PANI/DCAA dispersion followed an Arrhenius law. While a Vogel-Fulcher-Tammann law was found for the relaxation time of PANI/DCAA-FA dispersion. Above a certain temperature, 318 K for PANI/DCAA and 313 K for PANI/DCAA-FA, the rheological parameters of the dispersions changed, thus indicating a morphological change of polyaniline in the dispersion. In the same range of temperature, $\alpha$ and $\beta$ relaxation parameters undergo significant changes. Those changes in dielectric and rheological parameters seem to be related to a structural change occurring in the polyaniline organic dispersion systems while increasing temperature. An interesting correlation between permittivity and viscosity was obtained.

PACS
77.22.Gm - Dielectric loss and relaxation.
77.84.Jd - Polymers; organic compounds.
83.60.Fg - Shear rate dependent viscosity.

© EDP Sciences 2009


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