3D printing already plays a huge role in manufacturing, spanning almost every industry you could imagine. Moreover, various materials can be used to print a 3D part, like plastics and polymers, resins, metals, ceramics, composites, concrete, bio-materials, and even food! Still, wood somehow escaped the picture, as it’s not naturally occurring as a liquid. But that soon might change, as researchers from Rice University in Houston, Texas, developed a way to 3D-print our most beloved material from nature.
However, the team consisting of M.S.H Thakur, Muhammad Rahman, and Chen Shi, didn’t directly use wood as the 3D-printing ink. Instead, the researchers made a mix of all components you’d find in wood, like water, cellulose nanofibers, cellulose nanocrystals, and lignin. It’s basically the same stuff you’d find in trees, albeit arranged differently to make a viscous “wood” ink.
The best part – cellulose and lignin can be harvested from wood waste, which is present in every industry that uses wood, including forestry, furniture, construction, shipbuilding, packaging, paper, musical instruments, etc. That’s a lot of waste that could now be re-used to manufacture complex parts using simple direct ink writing (DIW), where the ink is extruded through a nozzle and then rendered into a solid via sintering.
Yup, unfortunately, these parts can’t solidify at room temperature. Instead, once printed, the part will need to be freeze-dried at -85 °C (-121 °F) for 48 hours and then heated to 180 °C (356 °F) for 20 to 30 minutes. The heating is necessary to convert the lignin to molecular glue, which would then bind the cellulose crystals and fibers.
By now, you must be thinking that artificially produced lignin plus cellulose isn’t wood. You’d be right, but the researchers promise that the 3D-printed parts look, feel, behave, and even smell like wood. Considering there is no waste produced in the 3D printing process, we can forgive the researchers for not using “real wood.” Besides, to make the process even more eco-friendly, the team is already looking into alternatives that would replace the sintering and heating steps.
Article & Image Source: Rice University
