Hemicellulosic Sugars and Lignin:A Synergistic Combination for the Synthesis of High-Performance Bioresins

To render biorefineries economically viable, it isimportant to maximize the value of all of the processedlignocellulosic biomass. However, the hemicellulose fraction isoften overlooked in current biorefinery strategies. In this study, wedemonstrate the valorization of lignin and sugars, both obtainedthrough dilute acid solvolysis of lignocellulosic biomass, for theproduction of lignin/sugar-based polyurethane (LSPU) films aspartial substitutes for petroleum-derived polyols. LSPU films wereprepared using a four-component system, comprising lignin,hemicellulose-derived sugars, polytetrahydrofuran, and hexamethylene diisocyanate isocyanurate trimer. Our study involvedoptimizing the sugar content in the LSPU film formulations toinvestigate how the presence of sugar impacts the films’ structural,thermal, and mechanical properties. The results showed that as the concentration of sugar increased, the mechanical properties ofthe LSPU films were improved in comparison to those of sugar-free samples. Additionally, the LSPUs were evaluated as PUadhesives, where the mechanical properties of the bonded joints, comprising wood substrates, were measured using single-lap sheartests. The shear strength values obtained were comparable to or even higher than those of a commercial PU glue. Our findingsdemonstrate the potential of incorporating hemicellulose-derived sugars in LSPUs for improved mechanical and adhesion properties,offering new possibilities for the valorization of lignocellulosic derivatives