Construction of xylan-based wood adhesive via tailoring crosslinking and interfacial chemical covalent bonding

Currently, low adhesion and poor water resistance are the main factors limiting the application of biomass adhesives. Based on these factors, in this study, branched epoxy compounds were synthesized from erythritol, xylitol and sorbitol, which were further reacted with the synthesized aminated xylan to obtain biomass adhesives. It is noteworthy that amino-rich activated wood surfaces were constructed and a "sandwich" type multiple cross-linked network was formed by chemical bonding between the adhesive and the activated wood surfaces. The dry/hot water/boiling water bond strength of the activated wood plywood were 3.13/1.54/1.18 MPa, which were 42.9%/108.1%/156.5% higher than those of the natural wood plywood, respectively. The plywood prepared from the activated wood interface showed excellent bond strength and water resistance. In this study, the wood surface was modified with orientated functional groups based on the mechanism of cross-linked network formation in the adhesive, resulting in the formation of stable chemical bonds between the adhesive and wood interfaces. This is the key to improving the interfacial adhesive interactions and ultimately the properties of the plywood.