From floors to furniture, it is hard to beat the natural aesthetics and warmth of wood. Wood is also arguably one of the most sustainable functional materials. But making objects from the material results in tons of waste.
Researchers have now come up with a way to turn this waste back into a wood-like material. They used the waste to make a water-based ink with which they 3D-printed objects. The recycled material had the appearance, texture, smell, and strength of natural wood.
“The ability to create a wood structure directly from its own natural components sets the stage for a more eco-friendly and innovative future,” said Muhammad Rahman, a professor of materials science and nanoengineering at Rice University in a press release.
Leftovers from wood processing are used today to make particle board, fuel, and mulch. But the new technique could allow people to make a sustainable, biodegradable alternative to plastic.
Materials for 3D printing wood are already available on the market today. But they are typically composed of around 70 percent bioplastics. The new 3D printing material, on the other hand, is made only of compounds found in wood. There are no binders or glues, and processing the material does not take any harsh chemicals like acetone.
The Rice team started with wood chips and treated them to extract two main molecules that make up wood: cellulose and lignin. They broke down the cellulose to form tiny nanoscale fibers and crystals. Then they mixed lignin with cellulose nanofibers and nanocrystals at carefully calculated ratios, and added water to make a clay-like paste that could be used as an ink.
By pushing this ink through a wide nozzle and building up layers of it, the researchers could 3D print objects such as tiny furniture models and a honeycomb. To increase the strength of the 3D-printed objects, the researchers freeze-dried them and then pressed them while heated to temperatures of up to 180°C.
In mechanical tests that involved pressing and bending, the recycled wood performed as well as natural balsa wood. Rahman and his colleagues from Rice University and Oak Ridge National Laboratory presented their results in the journal Science Advances.
The researchers say that they now plan to work on finding ways to boost the strength of the 3D-printed wooden structures without using energy-intensive processes such as freeze-drying and hot-pressing.
Source: Md Shajedul Hoque Thakur et al. Three-dimensional printing of wood. Science Advances, 2024.
Photo courtesy of Gustavo Raskosky/Rice University.
