Dielectric relaxation of water adsorbed on chemically treated woods

Abstract

Abstract Changes in the dielectric relaxation due to water adsorbed on eight types of chemically treated woods, as well as untreated wood (Picea sitchensis Carr.), with moisture content (MC) were investigated in the temperature range between −150°C and 20°C and in the frequency range between 100 Hz and 1 MHz. Cole-Cole's circular arc law was applied to the results of dielectric measurements conducted at seven levels of relative humidity (RH), and the relaxation spectra at −75°C were calculated. The theory of rate processes was applied to the dielectric relaxation resulting from the motions of water molecules adsorbed on the untreated and chemically treated woods, and the binding state of adsorbed water was examined. The relaxation magnitude increased with increasing MC, irrespective of the chemical treatment. The distribution of relaxation times decreased in the MC range below 1%, but increased with increasing MC at higher levels. The generalized relaxation time increased up to 5% MC, then decreased. The enthalpy-entropy compensation phenomenon was observed in the dielectric relaxation, which was derived from the adsorption of water molecules on the chemically treated woods. The binding states of adsorbed water and ice were similar. The water molecules adsorbed on wood may have produced a very wide variety of cohesive structures in the chemically treated woods.