INFLUENCE OF WATER ON THE DIELECTRIC BEHAVIOR OF CHITOSAN FILMS

The dielectric properties of chitosan films with a degree of deacetyla tion of 86% have been investigated in the frequency range of 10(3)-10( 6) Hz covering a broad range of temperatures from -150 to 150 degrees C. The variation of the dielectric properties with temperature has bee n associated with two dielectric processes: (a) a local relaxation att ributed to the presence of hydrogen-bonded water appearing at low temp eratures (b) a conduction process related to water molecules which bec omes desorbed upon heating at T > 80 degrees C. Isothermal dielectric experiments have been performed in order to follow, in real time, the occurrence of both, the water sorption and desorption processes.