Scientists have successfully developed cellulose fibres that are stronger than steel and aluminium.
A novel procedure developed by a Swedish-German research team spins extremely tough filaments from tiny cellulose fibrils by aligning them all in parallel during the production process.
"Our filaments are stronger than both aluminium and steel per weight," said lead author Fredrik Lundell from the Wallenberg Wood Science Centre 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," said Lundell.
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," said 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," said Roth.
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," said co-author Dr Daniel Soderberg 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," said Soderberg.
The fibres are much stronger than all other previously reported artificial filaments from cellulose nano fibrils.
In fact, the artificial filaments can rival the strongest natural cellulose pulp fibres extracted from wood at the same degree of alignment of the nano fibrils.
The research was published in the journal Nature Communications.
