A multifunctional lignin-based composite ultra-adhesive for wood processing.

Phenolic resin adhesives are usually synthesized using phenol and formaldehyde. Both of them are fossil-based and the resins are not biodegradable. Replacing them with whole biomass-based lignin and furfural is attractive. However, it is still difficult to wholly replace them, especially lignin due to its low reactivity. In this paper, a preparation method for a composite adhesive was presented. A lignin-based composite adhesive was prepared by using a deep eutectic solvent (DES), lignin, and furfural. The lignin-based composite adhesive is a machinable adhesive for wood, and the adhesive strength for the paulownia plate reached 5.71 MPa. The adhesive also possessed outstanding flame retardance performance with a V0 grade and the ultimate oxygen index of the adhesive-coated wood was 30%. Interestingly, it also had excellent thermal insulation and photothermal performances. Importantly, wood chips can also be processed into strong regenerated wood using the adhesive. [ABSTRACT FROM AUTHOR]