Bio-based epoxy resins from biorefinery by-products

In the transition from petrol to bio-based chemicals, the total utilization of the components from biomass during the biorefinery process can be regarded as the key to its success. Currently, the lignin obtained from the biomass during the pulping of wood is burned; however, this component has the potential to be an alternative to petroleum for producing aromatic feedstocks. Additionally, glycerol is a by-product of biodiesel production. In this work, epoxy resins were synthesized from these two components in an environmentally compatible process using water as the reaction medium (as opposed to organic solvents). Base-catalyzed depolymerized lignin, the only depolymerized lignin available at a multi-kilogram-scale, was chosen as the lignin source. This depolymerized lignin acts as the curing agent for glycerol, which results in entirely bio-based resins. Depolymerized lignin imparts rigidity to the resins, and the glass transition temperature (Tg) increased as the lignin content of the resin increased. Thermogravimetric analysis (TGA) data showed that the resins had a relatively high thermal stability with the onset of thermal degradation starting at 281 °C.