Conductance and relaxations of gelatin films in glassy and rubbery states

The dielectric constant, epsilon', and the dielectric loss, epsilon", for g elatin films were measured in the glassy and rubbery states over a frequenc y range from 20 Hz to 10 MHz; epsilon' and epsilon" were transformed into M * formalism (M* = 1/(epsilon' - i epsilon")= M' + iM"; i: the imaginary uni t). The peak of epsilon" was masked probably due to de conduction, but the peak of M", e.g. the conductivity relaxation, for the gelatin used was obse rved. By fitting the M" data to the Havriliak-Negami type equation, the rel axation time. tau(HN), was evaluated. The value of the activation energy, E -tau, evaluated from an Arrhenius plot of 1/tau(HN), agreed well with that of E-sigma evaluated from the DC conductivity sigma(0) both in the glassy a nd rubbery states, indicating that the conductivity relaxation observed for the gelatin films was ascribed to ionic conduction. The value of the activ ation energy in the glassy state was larger than that in the rubbery state. (C) 1999 Elsevier Science B.V. All rights reserved.