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 °C. The electrical conductivity was investigated in the temperature range 303–453 K and in the frequency range 1 kHz–1 MHz. The α- to β-phase transformation was achieved in the PVDF matrix. The maximum of β-PVDF which is 91% was reached at 90 °C. It was concluded that the percolation threshold of PANI:PVDF composites depends strongly on the drying temperature. The increase in β-PVDF rate (F(β)) induces a change in both dc and ac conduction mechanisms. In fact, for the highest β-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 β-phase content, the charges transport is assured by the tunneling processes.