Discharging and thermally stimulated polarization (TSP) currents in aromatic polyamides

Discharging current measurements are reported in aramid paper over a wide range of temperatures and electric field strengths. The results show that at lower temperatures dipolar polarization occurs. With increasing temperature there is increasing contribution from interfacial polarization and at 200°C the latter mechanism is predominant. Measurement of thermally stimulated polarization currents supports the proposed mechanism. By separating the dipolar polarization currents from interfacial polarization currents additional evidence has been obtained for the proposed mechanism. An activation energy of 0.84 eV is obtained for the dipolar process. On the basis of Debye theory a relaxation time of 6.3×10⁴ s is obtained at 30°C