Percolation and dielectric relaxation in polypyrrole-Teflon alloys

Polypyrrole-polytetrafluoroethylene alloys were prepared and the complex permittivity was determined from d.c. to 6 GHz. An insulator-to-conductor transition occurs when increasing the polypyrrole volume fraction and is correctly fitted by a two-component mixing formula. A dielectric relaxation is observed and interpreted as the relaxation of charged-carrier hopping between localized states. The hopping model is in good agreement with the experimental results in the investigated range of alloy compositions.