Thermally stimulated depolarization current of a nonlinear optical side chain polymer

Thermally stimulated depolarization current (TSDC) of a nonlinear optical side chain polymer under various poling conditions is studied to characterize the relaxation process in it. To characterize the TSDC of the polymer, a bi-exponential function and an exponential function are used respectively. It is indicated that the TSDC, originated only from the alpha- or beta-relaxation process, can be adequately expressed with an exponential function for the low-temperature side of the TSDC curve. For the alpha-process, the results obtained from the TSDC data are compared to that obtained from both the dielectric spectrum and thermal degradation behavior. The effect of the space charge on the TSDC data is discussed. Based on the TSDC data, it is got that the relaxation strength of beta-process is only 3% of that of the alpha-process.