DIELECTRIC EFFECTS OF WATER IN WATER-CONTAINING SYSTEMS

The dielectric properties of several water-containing systems (synthetic polymers, saccharides, proteins, plant tissues) were systematically studied by means of the thermally stimulated depolarization currents (TSDC) method, following recently developed concepts for using the TSDC method to investigate the structures of water in different systems. The TSDC spectra recorded between 77 and 300 K exhibit several distinct relaxations which can be classified into three groups: relaxations due to the reorientation of water molecules themselves; dipolar relaxations, which are also present in the dry samples and which are influenced by water; and conductivity relaxations related with the water-dependent dc conductivity due to ions, mostly protons. In most cases, the results are compatible with a three-phase model: molecularly dispersed water tightly (non-rotationally) bound at primary hydration sites, loosely bound water in layers or clusters around primary hydration sites and free water at higher water contents.