Dielectric Relaxation Based on Adsorbed Water in Wood Cell Wall under Non-Equilibrium State. 1

Abstract

Summary In order to make clear the molecular mechanism of the dielectric relaxation based on adsorbed water in wood cell wall during moisture changing process, the temperature and frequency spectrums of dielectric processes of Sikkim spruce (Picea spinulosa Griff.) were measured in three different adsorption processes. Three levels of relative humidity used were 40, 80 and 100 %, respectively, and the temperature was kept at 20°C. In oven-dry state, relaxation process I based on the reorientation of CH2OH groups in amorphous region of wood cell wall was observed. While in moist state, relaxation process II based on ionic conductivity and relaxation process III based on the additive reorientation of CH2OH groups and adsorbed water molecules occurred. Within higher humidity region, relaxation process IV concerned with adsorbed water in lignin was observed in the initial adsorption period, but it vanished with further adsorption.