July 2, 2019
The rapidly expanding adoption of 3D printing has raised some environmental concerns, as most processes rely on resin-based processes that often create large waste streams. Researchers at Chalmers University of Technology in Sweden may have come up with a possible alternative – a wood-based ink that mimics the cellular architecture of wood. By printing products derived from trees, the process could enable the creation of more eco-friendly items.
According to the researchers, genetic coding gives wood unique properties relative to toughness, porosity and torsional strength, but wood-based materials are more difficult to process when it comes to printing.
Chalmers has come up with a way “grow” wood in exact shapes using 3D printing. By converting wood pulp into a nanocellulose gel, the researchers had previously created a type of ink that could be 3D printed. Now they have interpreted the wood's genetic code and then digitized it in order to guide the 3D printer. The arrangement of the cellulose nanofibrils can be precisely controlled during printing to replicate the “desirable ultrastructure” of wood.
“This is a breakthrough in manufacturing technology. It allows us to move beyond the limits of nature, to create new sustainable, green products. It means that those products which today are already forest-based can now be 3D printed, in a much shorter time. And the metals and plastics currently used in 3D printing can be replaced with a renewable, sustainable alternative,” said Professor Paul Gatenholm, who led the research via the Wallenberg Wood Science Centre at Chalmers.
You can read the article, “Materials from trees assembled by 3D printing - Wood tissue beyond nature limits,” in Applied Materials Today.
The printing gel also now includes hemicellulose, a natural component of plant cells, that acts as a sort of glue to provide additional strength to the material. According to Chalmers, that means wood-based products could be designed and printed much more quickly.
The team has already developed a prototype for new packaging concept. They printed out honeycomb structures with chambers in between the printed walls, and then encapsulate solid particles inside the chambers. The resultant product could be used to create air-tight packaging for food or pharmaceuticals.
“Manufacturing products in this way could lead to huge savings in terms of resources and harmful emissions,” Gatenholm said. “Imagine, for example, if we could start printing packaging locally. It would mean an alternative to today's industries, with heavy reliance on plastics and C02-generating transport. Packaging could be designed and manufactured to order without any waste”.
The team has also developed prototypes for healthcare products and clothing. The materials could also be used for 3D printing in space travel applications, and Chalmers is working with the European Space Agency and NASA on potential applications.
“The source material of plants is fantastically renewable, so the raw materials can be produced on site during longer space travel, or on the moon or on Mars. If you are growing food, there will probably be access to both cellulose and hemicellulose,” Gatenholm said.
Source: Chalmers University