Thermally stimulated depolarization current study in novolac phenol-formaldehyde resin

Abstract

Thermally stimulated depolarization of novolac phenol-formaldehyde resin performed in the temperature range from 298 to 423 K shows tow current peaks P1 and P2 at the temperatures Tm1 = (320 ± 2) K and Tm2 = (334 ± 6) K, respectively. The effects of the poling temperature, the strength and direction of the poling field, the electrode material, the electrode blocking, and light are investigated. The peaks are isolated and the activation energy, determined by the initial rise method amounts to 1.7 eV for P1, and 3.2 eV for P2. The appearance of P1 corresponds to the temperature of the glass transition and is due to the dipolar relaxation. The related dipole moment is found to be 2.6 D. The peak P2 behaves quite differently and is caused by the release of the trapped charge. [Russian Text Ignored].