Polarization and depolarization studies in pure and malachite green complexed free cellulose

Abstract

The mechanism of charge production and its persistence in pure and malachite green mixed ethyl cellulose (EC) films have been analyzed using short circuit thermally stimulated discharge current (TSDC) in conjunction with that of transient discharging current as a function of similar and dissimilar electrode metals, polarizing fields, and polarizing temperatures. The TSDC thermograms of EC were characterized by two peaks at 343 and 423 K in the case of similar electrodes. With dissimilar electrodes, however, a broad peak was observed between 413-433 K. Transient currents, have been found to follow the Curie-von-Schweidler law, characterized with different slopes in short and long time regions and having different values of decay constant. The corresponding energies are found to increase with measurement time of the discharge current. The conductivity of the films is increased on doping with malachite green. A close scrutiny of the observed results suggest that a dipolar mechanism coupled with space charge formation due to accumulation of charge carriers near the electrodes and subsequent trapping of such carriers in the bulk may be considered as the dominant mechanism responsible for discharging currents. The effect of doping with malachite green on the discharge current indicates the formation of molecular aggregates.