Monitoring of curing of liquefied wood and bonding of woodwith liquefied wood

Liquefied wood is a potential alternative to the synthetic adhesives which are used for the bonding of wood. Despite the ability of liquefied wood to self-crosslink, bonds formed during the bonding of wood with liquefied wood do not achieve sufficient shear strength and have poor resistance to water. For this reason the process of the curing of liquefied wood, the influence of various parameters on the shear strength of bonds, and the structure of bonds formed during the bonding were analyzed. It was found that the chemical curing of liquefied wood started after water and solvent had been removed from it. When bonding wood, the curing liquefied wood takes place faster because, in addition to evaporation, the transition of both vaporous components from the liquefied wood to the lamellas also occurs. During the bonding of 5 mm thick beech lamellas with liquefied wood having a negative pH, at optimal bonding conditions (180 °C, 12 min), a specific type of bond was formed. It consisted of a central part of carbonized wood cells of the bonded lamellas and the cured liquefied wood, and a narrow layer of partly delignified wood cells at the border between the central part and bonded lamella.