Enhanced stability of polyaniline/inorganic salt composites during temperature cycling

The electrical conductivity of polyaniline sulfate was recorded during cycl es between room temperature and 85, 105, 125 and 145 degrees C. After each temperature cycle the conductivity decreased. The maxima of the conductivit y-temperature heating curves are discussed. Composites of polyaniline sulfa te with inorganic salts (ammonium sulfate or potassium bromide) were treate d in the same manner. Experimental data and a simple model indicate that th e temperature dependence of the composite conductivity changes its characte r at ca. 80 wt% PANI. Composites containing more than 20 wt% inorganic salt exhibit lower decrease in the conductivity after cycling; i.e. they have a higher thermal stability of electrical properties than polyaniline sulfate alone. (C) 2000 Elsevier Science Ltd. All rights reserved.