Process Intensification of Thermoplastic Lignocellulose Production through High-Solids Reactive Extrusion Enabled by a Novel Recycle Loop

To reduce the reactant concentration necessary for producing a newly synthesized thermoplastic lignocellulose from forestry waste, this study explores the concept of a recycle stream as a chemical unit operation in a reactive extrusion process. Modified lignocellulose from the first pass was returned to the start of the extrusion process to act as a lubricant for the lignocellulose feedstock. By this action, a high lignocellulose content could be extruded without requiring costly lubrication alternatives such as plasticizing additives, solvents, or excessive quantities of liquid reactants. With 25% recycled material, a significantly improved processing state was found, allowing for a reduction in total reactant usage by 50% without change to the degree of modification and ultimately leaving less unreacted species in the final product. The thermoplastic nature of the modified lignocellulose was characterized by thermal and rheological analysis and was found to demonstrate greater flowability with any recycle stream fraction.