Dialdehyde Cellulose as a Bio-Based Robust Adhesive for Wood Bonding

Novel adhesives based on natural biopolymers with high performance are still desired for the wood industry, in order to replace conventional fossil-based adhesives on the market. In this study, aqueous solutions of dialdehyde cellulose (DAC) with various degrees of oxidation (DOs) and distinct concentrations were evaluated as robust adhesives for wood bonding, which has not yet been systematically studied. The adhesion performance of DAC adhesives was investigated using tensile shear strength measurements according to European standard EN302-1. Results showed the DO and the concentration of DACs had a predominant impact on the adhesion performance. The optimal formulation of DAC adhesives was found to be the aqueous solutions of DAC with a DO of 1.75 and a concentration of 40 wt %. The corresponding best bonding performance was represented by the bonding strength of about 9.53 MPa for beech wood specimens and 5.75 MPa for spruce wood specimens. Furthermore, wood specimens in shear strength tests mainly revealed a substrate failure mode rather than adhesive or cohesive failure. This indicates that the DAC adhesives possessed a stronger bonding strength than the wood itself. Therefore, our study demonstrates that DAC is a potential bio-based adhesive for wood bonding, especially under indoor conditions.