Novel cellulose composite material for the 3D printing of complex objects
A team of researchers from ETH Zurich (Switzerland) and the Swiss Federal Laboratories for Materials Science and Technology (Dübendorf, Switzerland) has 3D-printed objects with the highest concentration of cellulose in any object 3D printed before.
A team of scientists from ETH Zurich (Switzerland) and the Swiss Federal Laboratories for Materials Science and Technology (Empa; Dübendorf, Switzerland) have reportedly 3D printed objects with the highest cellulose content than any other object 3D printed.
The methodology, described in Advanced Functional Materials, combines direct ink writing 3D printing with a subsequent densification process, increasing the cellulose content in the object to volume fraction of 27%.
The team reports that they are the first to be able to produce solid objects with this level of cellulose content and complexity.
The ink used consists only of water and cellulose particles and fibers, measuring only a few hundred nanometers, with a cellulose content from 6–14% of the ink volume.
After printing this ink, the researchers put the objects into an organic solvent bath to densify the printed cellulose, causing the object to shrink and the relative amount of cellulose particles within the material to increase significantly.
The scientists then soaked the objects in a solution containing a photosensitive plastic precursor.
The densification process allowed us to start out with a 6–14% in volume of water-cellulose mixture and finish with a composite object that exhibits up to 27 volume percent of cellulose nanocrystals,” explained Michael Hausmann (ETH Zurich, Empa).
The team further explained that depending on the plastic precursor used, they were able to adjust the mechanical properties of the printed objects, such as their elasticity or strength, depending on the desired application.
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X-ray analysis and mechanical testing suggested that the cellulose nanocrystals are aligned similarly to those present in natural materials.
This means that we can control the cellulose microstructure of our printed objects to manufacture materials whose microstructure resembles those of biological systems, such as wood,” added Rafael Libanori, Senior Assistant in ETH Professor André Studart’s research group.
The team claims that the applications for this technology are far-reaching and wide-ranging but have already experimented with the 3D printing of an ear based on a human model. However, the team notes that more research and clinical trials are required before applications such as this are translated into clinical practice.
Sources: Hausmann MK, Siqueira G, Libanori R, Kokkinis D, Neels A, Zimmermann T, Studasrt AR. Complex-shaped cellulose composites made by wet densification of 3D-printed scaffolds. Adv. Funct. Mater. 30(4), 2070024 (2020); https://ethz.ch/en/news-and-events/eth-news/news/2020/03/printing-complex-cellulose-based-objects.html
Lead image: A 3D-printed ear cartilage imitation made of the cellulose composite material. (Photograph: Michael Hausmann/ETH Zurich/Empa). Available via: https://ethz.ch/en/news-and-events/eth-news/news/2020/03/printing-complex-cellulose-based-objects.html