(346a) Completely Biobased Lignin Adhesives for Plywood Applications

Lignin is one of the most abundant nonedible biomass found in nature and has the great potential for use as renewable feedstock for bio-based materials. When found in nature, lignin serves as a biogluethat covalently bonds and crosslinks various plant polysaccharides, affording plants mechanical strength. An application that directly draws on inspiration from lignin’s biological role is as wood adhesives. Lignin’s inherent low reactivity, however, is often only overcome by the use of toxic and environmentally harmful chemicals (e.g. formaldehyde, urea, or strong acids/bases) and conditions that are not amenable for use at the industrial scale. 

In this study, we describe a simple and environmentally benign procedure for the production of lignin-based adhesive for plywood applications. Adhesion is achieved via direct cross-linking with bio-derived cross-linkers without the need for pre-activation of lignin. Adhesion can also be achieved via catalytic repolymerization of lignin under aerobic conditions. The resulting formulation has high lignin content (up to 60%) with overall total bio-derived feedstock content of up to 100%. The use of various lignin sources in the formulation was explored. Mechanical properties of plywood assembled with our lignin-adhesives were comparable with those assembled using commercial plywood adhesives. 

The resulting bio-based adhesive formulation has high lignin content and contains only environmentally friendly and non-toxic components. Together with its ease of use in plywood assembly this formulation is potentially suitable for large-scale industrial applications.