Effects of Removal of Chemical Components on Moisture Adsorption by Wood

To investigate the effects on moisture sorption behavior of wood caused by the removal of chemical components, Populus euramericana flour (40 to 60 mesh) was divided into four groups: untreated, extractives removed, hemicellulose removed, and matrix removed. The samples at the fiber saturation point and under oven-dried conditions were separately exposed to relative humidities of 11%, 45%, and 75% at 25 °C for desorption and adsorption. Additionally, moisture changes were measured during the processes. The results showed that moisture changed rapidly for all four groups at the initial stage during sorption, after which the rate gradually decreased until a steady-state equilibrium was reached. Among the four groups, the samples from which extractives had been removed exhibited the highest moisture content and moisture sorption coefficient, followed by the untreated samples, hemicellulose removed, and matrix removed samples. With increasing relative humidity, the hysteresis ratio A/D of the samples increased, indicating a reduction in sorption hysteresis, which was further decreased by hemicellulose extraction.