Dielectric measurements in large frequency and temperature ranges of an aromatic polymer

¹ Université de Toulouse, UPS-INPT, LAPLACE (Laboratoire Plasma et Conversion d'Énergie), 118 route de Narbonne, 31062 Toulouse Cedex 9, France
² CNRS, LAPLACE, 31062 Toulouse, France

Corresponding author: sombel.diaham@laplace.univ-tlse.fr

Received: 3 July 2009
Revised: 10 September 2009
Accepted: 12 October 2009
Published online: 26 November 2009

Abstract

The characterization of the BPDA/PDA polyimide (PI) at high temperature up to 400 °C, thanks to dielectric relaxation spectroscopy (DRS) in the 10^-1 Hz to 10⁶ Hz frequency range, allows the determination of the dc electrical conductivity (σ_dc). In such a high temperature range, the dielectric spectra are modified by the extrinsic electrode polarization phenomenon (EP) response. A model is proposed which coupled to the DRS results allows evidencing and quantifying the effect of the EP. The proposed method gives a simple way to determine the intrinsic σ_dc values from the effective ac dielectric response, improving the accuracy and reducing the duration of measurement. For BPDA/PDA PI, the resulting σ_dc values range from 4 × 10^-11 to 8 × 10^-6 Ω^-1 m^-1 for temperatures between 200 and 400 °C, with an activation energy of the conduction phenomenon of 0.55 eV.