POSITRON-ANNIHILATION LIFETIME STUDIES AND DOPPLER BROADENING MEASUREMENT ON POLYANILINE

Polyaniline is studied by the PALS (positron annihilation lifetime spe ctra) as a function of temperature which varies from 145 to 315 K and by the DBARS (Doppler-broadened annihilation gamma-radiation spectra) as a function of protonation level. The variation of positron lifetime parameter shows three stages in our temperature range. This can be ex plained by two kinds of thermal effects, thermally generated lattice d efects and thermal expansion. The S parameter shows almost the same te ndency with the conductivity of the sample as a function of pH value, and can supply useful information on the conduction mechanism in polya niline.