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Dielectric properties of thermally aged poly aniline films doped with dilute sulfuric acid

✍ Scribed by Hiroshi Tsubakihara; Hideyuki Hasimoto; Hiroshi Okamura; Kohtaku Hayashi

Publisher
John Wiley and Sons
Year
1996
Tongue
English
Weight
523 KB
Volume
79
Category
Article
ISSN
8756-663X

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✦ Synopsis

An experimental study of the frequency-dependent dielectric properties of thermally aged polyaniline (pAn) films as a function of the concentration of the sulfuric acid solution used for dipping was performed. Infemng the morphological changes of the films from the results of ultraviolet-visible (UV-vis) and infrared (IR) absorption spectra and differential scanning calorimetry (DSC) thermograms, the dependency of the dielectric properties of thermally aged films on the protonation level is discussed. The effects of thermal aging on dielectric properties may be subdivided into two temperature regions. In the temperature range lower than 170" C, the dielectric constant was decreased, especially at high frequencies, and the tan 6peak was shifted to lower frequencies with increasing aging temperature. The mobility of pAn chains and electric dipole appears to be gradually restricted with increasing temperature. In the range higher than 210" C, pAn cannot be protonated and the dielectric properties are unaltered by dipping in dilute sulfuric acid (pH = 2), owing to crosslinking and oxidation of imine nitrogens.

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