Study of dielectric parameters of polyvinyl fluoride (PVF) by the thermostimulated currents (TSC) method

The thermally stimulated current method (TSC) is used to study the relaxation modes of the semicrystalline polyvinyle fluoride (PVF) polymer with a temperature that ranges (from -100°C to +100°C). The obtained spectrum shows three peaks as the temperature reaches -40°C, -1°C and +50°C. The shown peak at +50°C corresponds to the dielectric manifestation of the glass transition phenomenon and the peak at 0°C is attributed to the relaxation of H₂O molecules, trapped in the sample. Finally, we have attributed the peak which corresponds to around -40°C to the β relaxation of the material. The thermal windowing method enables us to evaluate the activation enthalpy and the relaxation times. The area under each elementary peak allows us to calculate the relative dielectric dispersion. Knowing this later and the relaxation time τ(T) enables us deducing experimentally the real and the imaginary part of the dielectric permittivity ε* for each temperature T and at an equivalent frequency in TSC (f = 10^-3Hz). The Cole and Cole diagrams are then deduced.