Formation and relaxation of poled order in dye doped polystyrene probed by isothermal and nonisothermal current measurements

Experimental results are presented on isothermal and nonisothermal electric current measurements obtained with a polystyrene and disperse red 1 guest-host system containing different percentages of the dye. The superposition principle holds for isothermal measurements and polarization currents seem to be almost independent of temperature in the range from 30 to 70 degrees C, below the glass transition temperature T-g. Thermally stimulated depolarization (TSD) current measurements show that the polarization induced in the samples depends strongly on poling conditions. Samples poled at temperatures above T-g have a lower polarization than those poled just below T-g. If the poling temperature T-p is far below T-g, the TSD current peak appears at much higher temperatures than T-p. The TSD curves differ somewhat from corresponding curves obtained during linear heating under applied voltage. (C) 1997 American Institute of Physics. [S0021-8979(97)06521-3].