ELECTRICAL TRANSPORT PROPERTIES OF PRISTINE AND IODINE DOPED POLYETHERIMIDES

Electrical conduction behavior of pristine and iodine doped polyetherimides (PEI) has been investigated under both transient and steady state conditions in the operating temperature range 50-200C at various electric fields of 12-60 kV/cm. The transient currents show the hyperbolic decay character, and the decay exponent p (a measure of current decay rate) decreases with temperature (T) and doping concentration. The origin of transient currents has been attributed to the dipolar nature of carbonyl (＝C＝O) groups and the ether linkages present in the main chain of PEI. The low field steady state conduction is ohmic in nature. The magnitudes of ionic jump distance (a) values do not favor an ionic type of conduction as a possible conduction mechanism in pristine as well as iodine doped PEI. The Schottky coefficients estimations do not show the possibility of Schottky type or Poole-Frenkel type conduction mechanisms in the low temperature region ( 120C), however, in the high temperature region ( 120C) there is a certain possibility of Poole-Frenkel type conduction mechanism in both pristine and iodine doped samples. The dual slope in the lgI versus 1/T curves for iodine doped samples indicates the presence of more than one type of trapping levels.