Water vapor sorption mechanism of furfurylated wood

Furfurylation could have a significant influence on wood hygroscopicity. However, moisture sorption and its mechanism of furfurylated wood are not fully understood. The aim of this study was to clarify the effect of furfurylation on sorption behavior and the mechanism of moisture sorption for furfurylated wood. Water vapor sorption isotherms were derived from dynamic vapor sorption apparatus and analyzed employing Hailwood–Horrobin model. Simultaneously, fiber saturation point and accessible hydroxyl groups were determined by NMR cryoporometry and deuterium exchange method, respectively. Results indicated that compared with control sample, furfurylated samples with different weight gain percents (WPGs) exhibited a little difference in reduced equilibrium moisture content (EMC R ) throughout RH range. Specifically, an increase below 30% RH and above 60% RH, and a reduction at 30–60% RH in EMC R of the furfurylated samples were showed, when compared with that of control sample. EMC R of 69% WPG displayed no distinguishable difference with that of 23% WPG over the whole RH range. Fiber saturation point increased with enhanced WPGs . However, accessible OH groups possessed a reduction with increased WPGs. The hygroscopic mechanism of furfurylated wood was associated with not only accessible OH groups but also other effects. This work could provide valuable guidance to control moisture-related properties of furfurylated wood.