Development of novel sustainable hyperbranched polyester wood adhesives from glycerol and maleic anhydride by solvent free method

Tri-formaldehyde glue is a widely used type of wood glue, but the formaldehyde that it releases is extremely harmful to human health. In this paper, a new biomass adhesive is proposed to replace the triple-formaldehyde adhesive. A hyperbranched polyester was prepared using two cheap biomass materials, glycerol and maleic anhydride, using a solvent-free method. The hyperbranched polyester has good thermal properties. As an adhesive, it has better bonding and water resistance properties than tri-formaldehyde adhesives. In particular, after 3 h of boiling water immersion, the plywood still had a shear strength of about 1.12 MPa, which still satisfied the requirements of Chinese national standard (≥0.7 MPa). What's more, this synthesis is simple to perform, does not require solvents, and leaves a clean by-product which is water. Therefore, the method is expected to be replicated in industry.