ELECTRICAL AND DIELECTRIC PROPERTIES OF POLYVINYL BUTYRAL .1. STUDIES OF CHARGE STORAGE MECHANISM

Charge storage properties in solution-grown polyvinyl butyral (PVB) thin films have been studied as a function of poling field (2.50 × 104-2.00 × 106 V/m), temperature (333°-398°K), time (5.40 × 103-1.44 × 10 sec), thickness of the films (0.8-4.5im), and heating rates of depolarization (2.8°-10°K/min) by the thermally stimulated discharge current technique. Two relaxation processes at 347° and 423°K are observed having activation energies of 0.36 ± 0.02 and 0.66 ± 0.02 eV, and relaxation times at 300°K of 4.19 × 10s and 0.86 × 106 sec, respectively. The magnitude of the maximum current corresponding to the 347 °K peak and the charge associated with it increase linearly with the poling field. It is associated with the deorientation of the aligned dipoles involving the acetate/hydroxyl groups. The peak at 423°K is attributed to the release of trapped electrons/holes. The increase in the activation energy associated with the peak at 423°K and the shift in its position toward higher temperatures with increase in the poling time and temperature suggest that the peak at 423°K is associated with a distribution of relaxation times. © 1979, The Electrochemical Society, Inc. All rights reserved.