LOW-FREQUENCY ALTERNATING-CURRENT CONDUCTION AND DIELECTRIC-RELAXATION IN POLYPYRROLE, POLY(N-METHYL PYRROLE), AND THEIR COPOLYMERS

The alternating current (ac) conductivity [sigma(m)(omega)], dielectri c constant (epsilon') and loss (epsilon '') of polypyrrole (PPY), poly (N-methyl pyrrole) [P(NMPY)] and their copolymers; poly(N-methyl pyrro le-pyrrole [P(NMPY-PY)I have been measured in the frequency range 10(2 )-10(6) Hz and in the temperature range 77-350 K. At 77 K, the ac cond uctivity can be expressed by the relation; sigma(ac)=A omega(s) where the slope s lies in the range 0.72-0.81 for these three polymers and d ecreases with increase in temperature. The well-defined loss peaks, wh ose magnitude decreases with the increase in frequency, have been obse rved in the temperature region where the measured ac conductivity appr oaches the direct current (dc) conductivity. These loss peaks have bee n associated with the movement of charge carriers in these polymeric f ilms. The dc conductivity has also been measured in the temperature ra nge 77-350 K and an attempt has been made to correlate it with dielect ric data. (C) 1996 American Institute of Physics.