Thermosetting Sucrose-Based Wood Adhesive with Enhanced Water Resistance and Bonding Performance by Constructing a Schiff Base Cross-Linking Network

In biomass materials, sucrose is one of the most abundant renewable resources, with the advantages of high purity and lower cost of acquisition. However, sucrose cannot be used as an adhesive directly because of its poor water resistance. Herein, in this work, a biomass sucrose-based adhesive with improved bonding strength and water resistance was prepared by oxidized sucrose (OS) and aminated tannins (NTA). The chemical structure of the sucrose-amidated tannin network was confirmed by Fourier transform infrared (FT-IR) and electron ionization mass spectrometry (ESI-MS), which indicates a Schiff base reaction occurred between oxidized sucrose and amidated tannin. Furthermore, the properties of the oxidized sucrose/aminated tannin (OSNTA) adhesive were tuned considering the effects of reaction time and mass ratio of sucrose/NTA. It reveals that increasing the mass ratio of sucrose/NTA is more advantageous to improve the bonding strength and water resistance of plywood than extending the reaction time. The dry and wet strengths of plywood bonded by the resulting adhesive can reach the relative standard requirement of GB/T 17657-2022 (≥0.7 MPa) when the mass ratio of oxidized sucrose and aminated tannin was 1:0.45. This work provides an approach for preparing a biobased non-aldehyde wood adhesive by using sucrose and tannin.