Synergistic improvement to dimensional stability of Populus cathay ana via hemicellulose removal/alkali lignin impregnation

Poor dimensional stability restricts the commercial utilization of fast-growing wood. In this study, fast-growing poplar (Populus cathayana) was treated by removing hemicellulose with hydrothermal treatment and impregnating alkali lignin via full-cell process, synergistically, for enhanced dimensional stability. After modification, hydroxyl groups were reduced in hemicellulose removed wood (DHC), alkali lignin was observed to fill in the cell lumens of vessels and wood fibers in the impregnated wood (AL) and in the wood modified by hemicellulose removal with alkali lignin impregnation (DHCAL). Compared with untreated wood, the volumetric swelling ratio of DHC and AL decreased by 11 % and 21 % under relative humidity (RH) of 89 %, respectively. The volumetric swelling ratio of DHCAL decreased by over 50 %, indicating a positive synergistic effect. The combination of hemicellulose removal and alkali lignin impregnation treatment improved the dimensional stability of wood significantly by reconstructing wood chemical components with various levels of hygroscopicity. This work could meaningfully contribute to the efficient utilization of fast-growing wood and promote the added value of industrial alkali lignin.