EFFECTS OF THERMAL AGING ON ELECTRIC-COND UCTIVITY OF POLYANILINE

Results of electrical conductivity and optical absorption spectra meas urements of polyaniline are reported. Samples prepared by casting were heated at 90 approximately 270-degrees-C and then dipped into aqueous solutions of H2SO4. The conductivity increases with the decrease of t he aging temperature. In the case of lower heating temperatures up to 190-degrees-C, the doping may result in a oxidation of the amine units to imine units, which would enhance the formation of the polaron band and the density of free carriers. On higher temperature treatment, th ermally induced changes in morphology, crosslinking, and/or other chem ical reactions should lower the level of the oxidation of amines, prev ent formation of the polaron band, and suppress the conductivity.