Electrical properties of polypyrrole/ polymethylmethacrylate composites
in the frequency range of 100 Hz-100 kHz
F. Gmati1*, A. Fattoum1, A. Belhadj Mohamed1, H. Zangar2, A. Ooutzourit3, M. S. Achour4
1Centre de Recherches et de Technologies de l’Energie, Technopole Borj Cedria, BP 95, Hammam-Lif, Tunisie.
2Faculté des Sciences de Tunis, université de Tunis El Manar, 2092 El Manar, Tunisie.
3Faculté des Sciences Semlalia, université Kadi Ayyad Marrakech, Maroc;
4Faculté des Sciences de Kénitra, université Ibn Tofail, Maroc
* Corresponding author.
Received: 30 March 2006; revised version accepted: 14 July 2006
Conducting composites of polypyrrole /poly(methyl methacrylate) are prepared with different weight percentages 2, 4, 6 and 8% of dispersed conducting polypyrrole (PPy) in the insulating matrix of poly(methyl methacrylate) (PMMA). Conductivity measurements have been reported in the frequency range of 100 Hz - 100 kHz and in the temperature domain of 23 - 100 °C. The variation of the conductivity with weight percentage of PPy, shows a percolative behaviour with a threshold near 4%. It has been observed that the conductivity of these samples increases with increasing temperature. The direct conductivity in our composites was analysed by the Variable Range Hopping model (VRH); and the best results have been achieved for the one–dimensional model. In the low temperature region and at high frequencies, the alternative conductivity in the present composites can be described by the power law sac (w,T) = A (T) ws (T), where the exponent s decreases with temperature; the alternative current (ac) conduction mechanism is predicted by the overlapping polaron tunnelling and by the Correlated Barrier Hopping of Elliot (CBH) models.
Keywords: Conducting polymer; Conductivity; Composites; VRH; CBH; Polaron tunnelling.