Effect of α- to β-transformation on the dc and ac conductivity mechanism in polyaniline: Polyvinylidene fluoride composites films

Polyaniline:Poly (vinylidene) fluoride (PANI:PVDF) composites were prepared by varying PANI weight percentages from 0% to 5%. PANI:PVDF films were dried at three different temperatures: 30, 90 and 120 degrees C. The electrical conductivity was investigated in the temperature range 303-453 K and in the frequency range 1 kHz-1 MHz. The alpha- to beta-phase transformation was achieved in the PVDF matrix. The maximum of beta-PVDF which is 91% was reached at 90 degrees C. It was concluded that the percolation threshold of PANI:PVDF composites depends strongly on the drying temperature. The increase in beta-PVDF rate (F(beta)) induces a change in both dc and ac conduction mechanisms. In fact, for the highest beta-phase, dc and ac conductivities are governed respectively by Mott's three-dimensional variable range hopping (3D VRH) and correlated barrier hopping (CBH) model. However, for the lower beta-phase content, the charges transport is assured by the tunneling processes. (C) 2014 Elsevier Ltd. All rights reserved.