Researchers at the Department of Energy’s Oak Ridge National Laboratory have achieved this for an intractable biorefinery byproduct, lignin, through the development of a new composite material well-suited to additive manufacturing. ORNL scientists have combined a melt-stable hardwood lignin with other materials-conventional plastic, a low-melting nylon, and carbon fiber-to create a composite that has suitable characteristics for extrusion and weld strength between layers during the printing process, they said. “ORNL’s world-class capabilities in materials characterization and synthesis are essential to the challenge of transforming byproducts like lignin into co-products, generating potential new revenue streams for industry and creating novel renewable composites for advanced manufacturing,” he said. Lignin is not an easy material with which to work; it chars easily and can only be heated to a certain temperature for softening and extrusion from a 3D printing nozzle. The team found success in developing a composite for 3D printing by combining lignin with nylon. To understand why the material combination reacted like it did, the scientists studied its molecular structure by conducting neutron scattering at the High Flux Isotope Reactor and used advanced microscopy at the Center for Nanophase Materials Science at ORNL. What they found is that the combination of lignin and nylon “Appeared to have almost a lubrication or plasticizing effect on the composite,” Naskar said. The ORNL team has a patent pending on its lignin-nylon composite, and plans to continue its work to refine the material and find other ways to process it, researchers said.
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