by Chalmers University of Technology
Researchers at Chalmers University of Technology, Sweden, have succeeded in 3-D printing with a wood-based ink in a way that mimics the unique “ultrastructure” of wood. Their research could revolutionise the manufacturing of green products. Through emulating the natural cellular architecture of wood, they now present the ability to create green products derived from trees, with unique properties—everything from clothes, packaging, and furniture to healthcare and personal care products.
The way in which wood grows is controlled by its genetic code, which gives it unique properties in terms of porosity, toughness and torsional strength. But wood has limitations when it comes to processing. Unlike metals and plastics, it cannot be melted and easily reshaped, and instead must be sawn, planed or curved. Processes which do involve conversion, to make products such as paper, card and textiles, destroy the underlying ultrastructure, or architecture of the wood cells. But the new technology now presented allows wood to be, in effect, grown into exactly the shape desired for the final product, through the medium of 3-D printing.
By previously converting wood pulp into a nanocellulose gel, researchers at Chalmers had already succeeded in creating a type of ink that could be 3-D printed. Now, they present a major progression—successfully interpreting and digitising wood’s genetic code, so that it can instruct a 3-D printer.
It means that now, the arrangement of the cellulose nanofibrils can be precisely controlled during the printing process, to actually replicate the desirable ultrastructure of wood. Being able to manage the orientation and shape means that they can capture those useful properties of natural 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 3-D printed, in a much shorter time. And the metals and plastics currently used in 3-D printing can be replaced with a renewable, sustainable alternative,” says Professor Paul Gatenholm, who has led this research within the Wallenberg Wood Science Centre at Chalmers University of Technology.
A further advance on previous research is the addition of hemicellulose, a natural component of plant cells, to the nanocellulose gel. The hemicellulose acts as a glue, giving the cellulose sufficient strength to be useful, in a similar manner to the natural process of lignification, through which cell walls are built.