Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Printing complex cellulose-based objects

27.03.2020

Trees and other plants lead the way: they produce cellulose themselves and use it to build complex structures with extraordinary mechanical properties. That makes cellulose attractive to materials scientists who are seeking to manufacture sustainable products with special functions. However, processing materials into complex structures with high cellulose content is still a big challenge for materials scientists.

A group of researchers at ETH Zurich and Empa have now found a way to process cellulose using 3D printing so as to create objects of almost unlimited complexity that contain high levels of cellulose particles.


The new 3D printing technology makes it possible to print filigree and robust structures from a cellulose composite material.

Credit: Michael Hausmann / ETH Zurich / Empa

Usage Restrictions: The rights to the images always remain with the person referred to as the copyright holder for them. Images published on ETH News may be used by other media and online portals only if ETH Zurich is specifically mentioned as the copyright holder and only in connection with the relevant ETH News article. Further distribution of images - for example, via download links - is permitted only with the approval of the editorial team.

Print first, then densify

To do this, the researchers combined printing via direct ink writing (DIW) method with a subsequent densification process to increase the cellulose content of the printed object to a volume fraction of 27 percent. Their work was recently published in the Advanced Functional Materials journal.

The ETH and Empa researchers are admittedly not the first to process cellulose with the 3D printer. However, previous approaches, which also used cellulose-containing ink, have not been able to produce solid objects with such a high cellulose content and complexity.

The composition of the printing ink is extremely simple. It consists only of water in which cellulose particles and fibres measuring a few hundred nanometres have been dispersed. The cellulose content is in between six and 14 percent of the ink volume.

Solvent bath densifies cellulose

The ETH researchers used the following trick to densify the printed cellulose products: After printing a cellulose-based water ink, they put the objects in a bath containing organic solvents. As cellulose does not like organic solvents, the particles tend to aggregate. This process results into shrinkage of the printed part and consequently to a significant increase in the relative amount of cellulose particles within the material.

In a further step, the scientists soaked the objects in a solution containing a photosensitive plastic precursor. By removing the solvent by evaporation, the plastic precursors infiltrate the cellulose-based scaffold. Next, to convert the plastic precursors into a solid plastic, they exposed the objects to UV light. This produced a composite material with a cellulose content of the aforementioned 27 volume percent.

"The densification process allowed us to start out with a 6 to 14 percent in volume of water-cellulose mixture and finish with a composite object that exhibits up to 27 volume percent of cellulose nanocrystals," says Hausmann.

Elasticity can be predetermined

As if that were not enough, depending on the type of plastic precursor used, the researchers can adjust the mechanical properties of the printed objects, such as their elasticity or strength. This allows them to create hard or soft parts, depending on the application.

Using this method, the researchers were able to manufacture various composite objects, including some of a delicate nature, such as a type of flame sculpture that is only 1 millimetre thick. However, densification of printed parts with wall thickness higher than five milimeters lead to distortion of the structure because the surface of the densifying object contracts faster than its core.

Similar fibre orientation to wood

The researchers investigated their objects using X-?ray analyses and mechanical tests. Their findings showed 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," says Rafael Libanori, senior assistant in ETH Professor André Studart's research group.

The printed parts are still small - laboratory scale you could say. But there are many potential applications, from customised packaging to cartilage-?replacement implants for ears. The researchers have also printed an ear based on a human model. Until such a product could be used in clinical practice, however, more research and, above all, clinical trials are needed.

This kind of cellulose technology could also be of interest to the automotive industry. Japanese carmakers have already built a prototype of a sports car for which the body parts are made almost entirely of cellulose-based materials.

###

Reference

Hausmann MK, Siqueira G, Libanori R, Kokkinis D, Neels A, Zimmermann T, Studart AR: Complex?Shaped Cellulose Composites Made by Wet Densification of 3D Printed Scaffolds. Advanced Functional Materials, Dec 9, 2019. doi: 10.1002/adfm.201904127

Media Contact

Rafael Libanori
rafael.libanori@mat.ethz.ch
41-446-332-932

 @ETH_en

http://www.ethz.ch/index_EN 

Rafael Libanori | EurekAlert!
Further information:
https://ethz.ch/en/news-and-events/eth-news/news/2020/03/printing-complex-cellulose-based-objects.html
http://dx.doi.org/10.1002/adfm.201904127

Further reports about: 3D Advanced Functional Materials ETH Zurich Nanocrystals plastic

More articles from Materials Sciences:

nachricht Thermophones offer new route to radically simplify array design, research shows
03.07.2020 | University of Exeter

nachricht The lightest electromagnetic shielding material in the world
02.07.2020 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

Im Focus: Gentle wall contact – the right scenario for a fusion power plant

Quasi-continuous power exhaust developed as a wall-friendly method on ASDEX Upgrade

A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...

Im Focus: ILA Goes Digital – Automation & Production Technology for Adaptable Aircraft Production

Live event – July 1, 2020 - 11:00 to 11:45 (CET)
"Automation in Aerospace Industry @ Fraunhofer IFAM"

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM l Stade is presenting its forward-looking R&D portfolio for the first time at...

Im Focus: AI monitoring of laser welding processes - X-ray vision and eavesdropping ensure quality

With an X-ray experiment at the European Synchrotron ESRF in Grenoble (France), Empa researchers were able to demonstrate how well their real-time acoustic monitoring of laser weld seams works. With almost 90 percent reliability, they detected the formation of unwanted pores that impair the quality of weld seams. Thanks to a special evaluation method based on artificial intelligence (AI), the detection process is completed in just 70 milliseconds.

Laser welding is a process suitable for joining metals and thermoplastics. It has become particularly well established in highly automated production, for...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

 
Latest News

Rising water temperatures could endanger the mating of many fish species

03.07.2020 | Life Sciences

Risk of infection with COVID-19 from singing: First results of aerosol study with the Bavarian Radio Chorus

03.07.2020 | Studies and Analyses

Efficient, Economical and Aesthetic: Researchers Build Electrodes from Leaves

03.07.2020 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>