Thermally stimulated discharge current studies in polyvinyl acetate thin films

TSD current studies as a function of polarizing field (0-9 kV cm -1 ) and thickness (1000-7000 AA) of polyvinyl acetate thin films show depolarization peaks at 326, 389 and 468K (heating rate 6K per min) with activation energies 0.22, 0.39 and 0.66 eV and relaxation times 7.50*10 2 , 9.12*10 3 and 3.70*10 6 s at 300K, respectively. A correlation has been found between 326 and 389K peaks and the beta and the alpha relaxation process which are attributed to the motion of the side groups and the orientation of the dipoles of the main polymer chain, respectively. The peak at 468K is related to the alpha ' relaxation process and is due to the release of the trapped space charges.