I came across this article yesterday that just left me scratching my head. Can you imagine recycled paper being stronger than steal? Well, a team of Swedish and German has successfully tested a method for producing ultra-strong cellulose fibers, and they believe the same principle should work with recycled fibers.
“Our filaments are stronger than both aluminium and steel per weight,” emphasizes lead author Prof. Fredrik Lundell from the Wallenberg Wood Science Center at the Royal Swedish Institute of Technology KTH in Stockholm. “The real challenge, however, is to make bio based materials with extreme stiffness that can be used in wind turbine blades, for example. With further improvements, in particular increased fibril alignment, this will be possible.”
So how does this work? According to the press release from DESY:
For their method, the researchers took tiny, nanometre-sized cellulose fibrils and fed them together with water through a small channel. Two additional water jets coming in perpendicular from left and right accelerate the fibril flow. “Following the acceleration, all nano fibrils align themselves more or less parallel with the flow,” explains co-author Dr. Stephan Roth from DESY, head of the experimental station P03 at PETRA III where the experiments took place. “Furthermore, salt is added to the outer streams. The salt makes the fibrils attach to each other, thereby locking the structure of the future filament.”
Finally, the wet filaments are left to dry in air where they shrink to form a strong fibre. “Drying takes a few minutes in air,” explains co-author Dr. Daniel Söderberg from KTH. “The resulting material is completely compatible with the biosphere, since the natural structure of the cellulose is maintained in the fibrils. Thus, it is biodegradable and compatible with human tissue.”
During their study, the researchers used filaments from fresh wood; however, the study’s authors believe that they should yield similar results with recycled paper.
“In principle, it should be possible to obtain fibrils from recycled paper also,” Lundell said. “The potential of recycled material in this context needs further investigations.”
Want to check out more? You can access the Hydrodynamic alignment and assembly of nano-fibrils resulting in strong cellulose filaments to read more about their research.