Thermally stimulated discharge conductivity of PVC thin film

The conductivity and thermally stimulated discharge currents (TSDC) in polyvinyl chloride (PVC) are studied in virgin and electret thin film samples. The V-I characteristics of the films at different temperatures reveal that there are three distinct regions, namely ohmic, square law and power regions. In the square law region, space charge limited conduction is observed. The possibility of Poole-Frenkel or Richardson-Schottky mechanism is also studied. The field-lowering coefficient ( beta ) is calculated. The Richardson-Schottky mechanism is observed. From -log sigma vs. 1/T plot, the activation energy is estimated. The electrical conductivity is found to increase with decreasing thickness. TSDC and conductivity are measured in the film of electrets in 313-333 K. Single relaxation peak is observed in the discharge current vs. temperature plot which is due to rotation of dipolar group at peak temperature. Initial rise method is adopted to calculate the activation energy. Similarly the activation energy is evaluated from -log sigma vs 1/T plot of electret samples. The structural investigations are made using the FTIR spectra. The spectra of virgin and electret samples are obtained in 400-4000 cm exp -1 wave number ranges. Significant change in the structure is observed due to injection charge carriers. The deformation of structure is also observed.