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. Bohli^{1, 2}, A. Belhadj Mohamed¹, V. Vignéras-Lefèbvre² and J.-L. Miane<sup>2

1</sup>  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, and 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.

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