Researchers at the Federal Institute for Materials Research and Testing in Germany have developed a sustainable new 3D printing material from termites and boring insect waste.
Using the pulverized wood particles and feces left by the tiny beetles after feeding, the scientists were able to create a unique raw material product with circular economy that could be 3D-printed as a binder jet without polymer additives. The bio-based material provided parts with low strength but high dimensional accuracy, which may make it ideal for creating environmentally friendly filigree structures in the future.
With termite damage, the researchers succeeded in 3D printing cubic structures with a dimensional accuracy of 200 μm. Photos via the Plos One Journal.
From excrement to raw material
As the world continues to seek sustainable manufacturing solutions, 3D printing is often touted in the industry as being more environmentally friendly than traditional production methods. Even so, the widespread use of oil-based photopolymers remains a challenge to the technology’s environmental friendliness and requires the creation of a circular alternative.
Natural raw materials are not only better for the planet, they also enable users to determine the life cycle of products early on during production and to adjust their throughput accordingly. Such homebrewed materials can also be formulated by recycling waste from the factory, making them both an inexpensive and sustainable solution.
Given that binding agents can handle virtually any powdered starting material, the technology has been widely used as a means of testing such novel formulations. However, refining these materials into powders with a suitable particle size remains a challenge. In order to counteract this, the German scientists have identified a newly optimized pellet, but in the most unlikely source: the termite.
The insect’s digestive system converts uneven woods into a compact cellulose-lignin mixture that (it turns out) is suitable for 3D printing without further processing. While earlier wood-based raw materials required printing polymer additives or the use of other bonding phases, termite damage does not, which makes processing uniquely easy.
The 3D-printed cubic structure of the scientists (picture) had a low packing density. Photo via the Plos One diary.
3D printing with termite damage
To make their wood-based raw materials, the scientists raised a small farm of European House Borers (EHBs) and termites and fed them for six months while they collected their droppings. It was found that all of the termite’s six-sided pellet-shaped feces were found to be nearly identical in size and exhibited excellent fluidity, making them ideal for making uniform layers.
Once they had enough raw materials, the team networked them to a thermal curing station on a commercial 3D printer with an ExOne binder and received a set of cubic samples. Interestingly, by changing the system’s binder saturation parameters, the researchers were able to determine the ratio for the delivery of structures with adjustable porosity.
In terms of layer thickness, the best reproducible result that could be achieved with termite feces was 800 μm, while the EHB proved to be more accurate at 100 μm. The team’s cube-shaped structure also had a dimensional accuracy of around 200 μm, but suffered not only from low packing density but also from oversaturation.
As a result, the part exhibited poor mechanical strength, and while scientists theorized that infiltration might increase its strength, they conceded that their material was not well suited for printing “ready-made objects”. Nevertheless, the researchers still believe that EHB-Frass has potential as a starting material for creating filigree structures, although reinforcement through post-processing is required.
Additive innovations in terms of sustainability
Over the past year, researchers have made significant strides studying the environmental impact of 3D printing and identifying new, more circular materials.
A team at the University of Freiburg has developed its own novel 3D printing material based on wood. By combining naturally derived lignin with cellulose spheres, the scientists were able to produce a unique biopolymer that could prove useful in lightweight construction applications.
Researchers from the State of Wichita, the University of Kansas, and Kansas State University have teamed up to develop a data algorithm to explore the potential of sustainable materials. With the help of data analysis, calculation approaches and diagnostic tools, the team wants to make environmentally friendly raw materials more accessible.
Elsewhere, scientists from Universidade NOVA de Lisboa (UNIDEMI) have highlighted the need for further research into the circularity of 3D printing. The team’s literature research revealed that polymeric factory waste has a particular potential for reducing waste and could be used as recycling material in the future.
The researchers’ results are described in detail in their article entitled “In search of biological starting material: 3D printing of wood particles from house drills and dry wood termite damage”. The research was written jointly by Rudy Plarre, Andrea Zocca, Andrea Spitzer, Sigrid Benemann, Anna A. Gorbushina, Yuexuan Li, Anja Waske, Alexander Funk, Janka Wilbig and Jens Günster.
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The picture shown shows three dry wood termites. Photo via the Plos One diary.
