Science

Biodegradable fibers as strong as steel made from wood cellulose

Fiber made from cellulose claimed to be as strong as steel
Fiber made from cellulose claimed to be as strong as steel
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Close-up of the new cellulose fibers
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Close-up of the new cellulose fibers
Fiber made from cellulose claimed to be as strong as steel
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Fiber made from cellulose claimed to be as strong as steel

A team of researchers working at Stockholm's KTH Royal Institute of Technology claim to have developed a way to make cellulose fibers stronger than steel on a strength-to-weight basis. In what is touted as a world first, the team from the institute's Wallenberg Wood Science Center claim that the new fiber could be used as a biodegradable replacement for many filament materials made today from imperishable substances such as fiberglass, plastic, and metal. And all this from a substance that requires only water, wood cellulose, and common table salt to create it.

To produce the new material, the team took individual cellulose fibers and broke them down into their component strands or "fibrils." They then separated and re-bound these fibrils in a technique that results in filaments much stronger than the original fiber. While fibrils have been separated in other studies – and even used in strengthening composite materials – it is the recombining of these fibrils into a super-strong filament that has never been achieved before and is asserted to be a considerable breakthrough in this type of research.

"We have taken out fibrils from natural cellulose fibers, then we have assembled fibrils again into very strong filament," said Fredrik Lundell, one of the researchers. "It is about 10 to 20 microns thick, much like a strand of hair."

The team constructed a "flow-focusing" device (similar to a small-scale extruder) to reassemble the fibrils after they had been mixed with water and sodium chloride. Controlling their reassembly by carefully adjusting the pressure at which they were injected, the researchers were able to produce continuous, consistent strands of fiber from the fibrils.

In this process, the way that they manipulate the angle at which the fibrils are brought together then determines the strength and stiffness of that fiber. For example, if the fibrils are aligned alongside each other, the material is rigid and inflexible, whereas if the fibrils are combined at angles to each other, the resulting material is more elastic and flexible.

The useful upshot of this is that the fibrils can be used to produce not only strong, steel-like fibers, but more fibrous ones as well. As a result, wood cellulose could be made to replace cotton in textiles, or even be used as a substitute for the glass filaments used in fiberglass used to construct boats and cars. And, as the new material retains its original cellulose, it is still biodegradable just like the wood it came from.

"Our research may lead to a new construction material that can be used anywhere where you have components based on glass fibers, and there are quite a few places," said Lundell. "The challenge we face now is to scale up the production process. We must be able to make long strands, many threads in parallel – and all this much faster than today. Nevertheless, we have demonstrated that we know how this should be done, so we've come a long way."

The work was carried out in cooperation with Deutsches Elektronen-Synchrotron elektronsynkrotronen (DESY) in Hamburg, Germany, with the research findings published in the scientific journal Nature Communications.

Photos: KTH

10 comments
Bob Stuart
I hope they have found a way to keep it from swelling with changes in humidity, and absorbing liquid water like a sponge.
justme70
You say "imperishable" like it's a bad thing.
Adriano
Biodegradable is a misleading concept. The question is, is it one hundred percent biofriendly? I would love to know before I can applaud.
Jim Sadler
I suspect that numerous uses will be found with the only limit being the cost of the material. I do wonder when they mention it as a substitute for fiberglass if it would be durable in boats and items exposed to water. Perhaps the fibers could be tricked into absorbing chemicals other than water that would help them resist water penetration. Products similar to micarta would be one possibility. Flooring made from such a strong material might be a blessing.
Margo Terrill
Why, oh why, oh why don't they consider using industrial hemp? It is much more earth friendly then using trees! I also resonate with others who've made comments about whether it is biofriendly and saying imperishable as if it's a bad thing! HEMP I SAY, industrial hemp!
DonGateley
@Margo: HEMP is one of an enormous number of bio sources of the cellulose that this process uses. It ain't limited to trees. Would it be stronger or weaker after re-processing? There's not enough information here to tell. I can't, however, think of too many applications for strong fiber where bio-degradability is not a disadvantage.
Michael Crumpton
They have made a spinning wheel for wood!
Fretting Freddy the Ferret pressing the Fret
Does it contain heavy metals? No. Does it contain, harmful/poisonous substances? No. Is it bio-friendly? Now answer it yourself.
mike65401
Adriano, you have to ask yourself is it more bio-friendly than what it replaces, not "Is it 100% bio-friendly?" BTW - The fibers used in fiberglass don't get exposed to water even in boat hulls. The fibers are encased in resin.
EvanescereIridescentLuminescence
Could you collect/make use of already fallen wood or dead wood (from pruning) for the cellulose in this? Would this product demand the need to cut down even more trees? Could the cellulose in bamboo or hemp be sufficient enough to substitute? Would like more specs info please.
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