Enhanced stability of polyaniline/inorganic salt composites during temperature cycling

The electrical conductivity of polyaniline sulfate was recorded during cycles between room temperature and 85, 105, 125 and 145 degrees C. After each temperature cycle the conductivity decreased. The maxima of the conductivity-temperature heating curves are discussed. Composites of polyaniline sulfate with inorganic salts (ammonium sulfate or potassium bromide) were treated in the same manner. Experimental data and a simple model indicate that the temperature dependence of the composite conductivity changes its character 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.