Dielectric behavior of polyetheretherketone (PEEK) using TSDC technique

The dielectric relaxation behavior of Polyetheretherketone (PEEK) has been investigated by using thermally stimulated discharge current (TSDC) technique. The dependence of TSDC characteristics of PEEK on poling temperature (T-P) [50-200 degrees C], poling field (E-P) [200-500 kV/cm], storage time (t(S)) [2-120 hrs] and various thicknesses 25 mu m, 50 mu m and 75 mu m have been investigated in the temperature range [60-230 degrees C]. The TSDC spectra shows a prominent maxima around glass transition temperature (T-g) i.e. at 143 degrees C named as alpha-peak and the other peak is observed around 200 degrees C named as beta-peak. The alpha-dipolar relaxation is taking place because of the movement of ketone (>C=0) dipoles linked to the main chain. The beta-peak is attributed to the space charges. It is observed that the magnitude of alpha-peak increases with the increase in poling field. The peak current and area under the alpha-peaks are found to be diminished with the increase of storage time (t(s)) for electrets. The amplitude of alpha-peak decreases with the increase in thickness. The activation energies for PEEK sample at different conditions in the present work are found to be 0.38 eV-1.70 eV. The values of activation energy (U) and pre-exponential factor (tau(o)) for alpha-relaxation are determined using Bucci plot method and support the nature of the relaxations.