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, α and β 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.