Analysis of the experimental distribution of relaxation times around the liquid-glass transition of poly(vinylidene fluoride)

The dielectric relaxation mode associated with the liquid-glass transition of a semicrystalline polymer, polyvinylidene fluoride, has been analyzed by the technique of fractional polarizations. A discrete distribution of relaxation times following an Arrhenius law has been obtained experimentally. The activation energy of the ''single'' relaxation processes are distributed according to a Gaussian function. Moreover, these relaxation times follow a compensation law. These results allowed us to introduce a continuous distribution of relaxation times whose parameters are temperature dependent. The validity of the method was verified for the thermally stimulated current spectra. Use is made of this distribution to compute the temperature and frequency dependence of the complex dielectric permittivity. (C) 1996 American Institute of Physics.