Preparation of high water resistance full biomass adhesive by ultrastrong crosslinking with gelatin, citric acid and sucrose

The construction of laminated composites using biomass materials for furniture manufacturing has important research value and practical significance. Gelatin is a renewable, non-toxic biomass resource that can be used to address the environmental problems caused by petroleum-based materials. However, its low mechanical strength and poor water resistance have hindered its use as a wood adhesive. In this work, gelatin (GE) is used as the main raw material, citric acid (CA) and sucrose (Su) are used to construct a highly efficient crosslinking water-resistant structure, and GE/Su-CA adhesive was prepared and used to produce laminated composites. FTIR, 13C NMR, XPS and GPC proved that citric acid can cross-link with gelatin/sucrose and form a tight network structure through covalent (amidation, esterification) or non-covalent (hydrogen bond, ionic bond) bonding, thereby enhancing the bonding performance and water resistance of the laminated composite materials. The curing and thermal stability of GE/Su-CA adhesive were studied by DSC and TGA. The results showed that GE/Su-CA had good thermal stability. The influence of the distribution ratio, hot-press temperature, hot-press time, and other factors on the adhesive strength and water resistance of the composite system is studied. The results show that the dry shear strength of the laminated composite prepared by the adhesive can reach 1.91 MPa, and the hot water immersion and boiling water immersion strengths can reach 1.41 MPa and 1.37 MPa respectively, exceeding the GB/T17657-2013 standard (≥0.7 MPa). The experimental process is simple and environmentally friendly, and the prepared GE/Su-CA adhesive has excellent performance. The research results of this project will provide a new way to prepare high-performance and environment-friendly gelatin-based laminated composites.