Conductivity spectroscopy in aromatic polyimide from 200 to 400 °C

Dielectric relaxation spectroscopy experiments have been performed in a polyimide (PI) in order to measure its electrical conductivity from 200 to 400 degrees C. The high temperature static (dc) conductivity in PI appears as superimposed by electrode polarization due to the building up of thin space-charge capacitor layers at the bulk-electrode interfaces of the metal-insulator-metal structure making the conduction phenomenon difficult to identify in dielectric spectra. However, the dynamic (ac) conductivity plot versus frequency allows for an approximation of the dc conductivity in PI which was reported here up to 400 degrees C with values reaching 10(-6) Omega(-1) m(-1) at 400 degrees C.