Low‐frequency dielectric behavior of poly(vinylidene fluoride)

Abstract An explicit mechanism is described for the anomalous increase in dielectric constant and dielectric loss at low frequencies and high temperatures for poly(vinylidene fluoride) containing ionic impurities. Relations are proposed for the ionic contributions, ε i ″ and ε i ″, to the dielectric constant and dielectric loss: where v 0 and D 0 are the concentration and the diffusion coefficient of the mobile ions at infinite temperature, q is the charge of an ion (in cgs electrostatic units), l is the distance between electrodes, k is the Boltzmann constant, T is the absolute temperature, E d is the apparent activation energy for diffusion of the ions, and W is the dissociation energy of the ionic impurities. From the slopes of curves of log ε T ′ versus 1/ T and log ε″ T versus 1/ T for poly(vinylidene fluoride), energies E d = 34 kcal/mole and W = 342 kcal/mole were obtained.