Regulation of bonding performance in cellulose-based adhesive and adhesive film via wood surface activation

To address the inadequate intrinsic strength and weak interfacial bonding of biomass-based adhesives while overcoming the environmental and health concerns associated with formaldehyde emissions from traditional petroleum-based wood adhesives, this study developed a high-performance adhesive system through crosslinking network design and interface engineering. Amino-functionalized polyvinyl alcohol (A-PVA) was prepared by modifying polyvinyl alcohol (PVA) with 3-aminopropyltriethoxysilane (APTES). A-PVA was then crosslinked with diacetyl cellulose (DAC) via the Schiff base reaction to produce a cellulose-based liquid adhesive (A-PVA-DAC). Meanwhile, an adhesive film was obtained using the flow-coating method, which was also suitable for wood bonding. The wood surface with epoxy groups was treated by γ-glycidoxypropyltrimethoxysilane (KH-560), and interacted with the adhesive with amino groups under hot-pressing to enhance the interfacial adhesion via covalent bonds. The liquid adhesive prepared with an A-PVA to DAC mass ratio of 1:1 exhibited optimal performance. Under hot-pressing conditions at 140 °C, plywood specimens using epoxy-functionalized wood surfaces (EWS) as the substrate achieved a specimen retention rate of 91.67% after boiling water treatment, with a bond strength of 1.18 MPa, which is 197% that of plywood prepared using natural wood surface (NWS). The plywood manufactured using adhesive films exhibited dry strength, cold water strength, and hot water strength of 1.58 MPa, 1.10 MPa, and 0.92 MPa, respectively. Although the bonding strength of plywood using adhesive films was lower than that of plywood using liquid adhesives, adhesive films offer greater convenience in storage and transportation. This work provides novel insights into enhancing the performance of biomass adhesives and developing novel resin adhesive films through the design of crosslinked networks and interfacial engineering regulation. • The cellulose-based adhesive and adhesive film for wood bonding were prepared. • The interface engineering strategy increased the adhesive’s dry strength by 44.19%. • Plywood’s strength reached 0.71 MPa after soaking in water for 72 h and redried. • A type of plywood suitable for use in humid environments was prepared. • The present work provides ideas for developing novel resin adhesive films.