Inhibiting wood-water interactions by hydrothermal hemicellulose extraction combined with furfurylation

Wood-water interactions affect durability and performance of wood products, such as dimensional stability and biodegradation. To upgrade wood, a combined modification via hemicellulose extraction and furfurylation was proposed to inhibit wood-water interactions. More intense hemicellulose extraction caused larger voids and led to higher pore volume. The increment of porosity resulted in more uniform distribution of polymerized furfural resin in cells, as indicated by scanning electron microscopic and confocal laser scanning microscopic observations. The combined modification greatly reduced surface wettability with an increase of water contact angle (CA) of over 134% at 100 s. With hemicellulose extraction, polymerized furfural resin partially occupied the accommodation initially for water molecules and reduced accessible sorption sites, causing water absorption (WA) of wood to decrease by over 30% after soaking in water for 768 h. Dynamic moisture sorption was weakened after combined modification, and the moderate hemicellulose extraction combined with furfurylation reduced the moisture content by over 50% due to incorporative changes of chemical sorption sites and physical porosity. The results confirmed the efficiency of the combined modification in inhibiting wood-water interactions and indicated the importance to accurately control hemicellulose content during modification. This study could provide useful information for sustainably enhancing wood performance and upgrading low-quality wood.