Investigation of the molecular dynamics of water in void spaces of wood using dielectric measurements

We performed dielectric measurements of an evergreen conifer tree, Cryptomeria japonica, impregnated with various aqueous solutions along the fiber direction in the frequency range of 10 MHz to 10 GHz at room temperature to investigate the molecular description of water and solute molecules in void space of the wood. The Cole−Cole-type relaxation process reflecting the motion of the water and solute molecules is observed in the GHz region. The water content dependence of the shape of the dielectric relaxation spectra markedly deviates from that of bulk state, while the relaxation time is similar to that of each bulk solutions. This characteristic dielectric property is interpreted that the fractionation of the hydrogen bond network formed by water and solute molecules occurs caused by the molecules being constrained to the inner walls of the wood voids.