Materials

New wood nanofiber biomaterial steals strength record from spider silk

New wood nanofiber biomaterial...
A scanning electron microscope image of the cellulose nanofiber material, derived from wood, which is now the strongest biomaterial ever made
A scanning electron microscope image of the cellulose nanofiber material, derived from wood, which is now the strongest biomaterial ever made
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A scanning electron microscope image of the cellulose nanofiber material, derived from wood, which is now the strongest biomaterial ever made
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A scanning electron microscope image of the cellulose nanofiber material, derived from wood, which is now the strongest biomaterial ever made

Spider silk has long held the title of strongest natural biomaterial, so scientists have been trying to harness it, mimic it and even improve on the recipe for years. Now, researchers at the KTH Royal Institute of Technology have developed a new biomaterial out of wood nanofibers that steals the strength record.

Wood is one of nature's sturdiest materials, but that doesn't mean it can't be made even better. Researchers recently "densified" the material to make what they call "super wood," and previous work from the KTH team made wood fibers as strong as steel.

Key to both the previous and current KTH work are what are known as cellulose nanofibrils (CNFs). These tiny fibers come together to make the cell walls of wood strong and stiff, and working out how to assemble them on the nanoscale has helped the team build a stronger material.

The researchers used a flow-assisted assembly technique that involved suspending nanofibers in water, in channels just 1 mm wide. Deionized and low pH water flows through, which helps the CNFs align in the right direction and self-organize into tightly-packed bundles. The resulting material is strong, stiff, lightweight and large enough for practical use, creating what the team says is the strongest biomaterial made so far.

"The bio-based nanocellulose fibers fabricated here are eight times stiffer and have strengths higher than natural dragline spider silk fibers, generally considered to be the strongest bio-based material," says Daniel Söderberg, corresponding author of the study. "The specific strength is exceeding that of metals, alloys, ceramics and E-glass fibres."

In numbers, the team measured the tensile stiffness of the material to be 86 gigapascals, and its tensile strength to be 1.57 gigapascals. Even the weakest individual fiber they made was found to be stronger than previously-created CNF fibers.

The researchers say the technique could be used to make strong, lightweight materials for building planes, cars, bikes and furniture. It could also help assemble other nanofibers too, such as carbon tubes.

The research was published in the journal ACS Nano.

Source: KTH Royal Institute of Technology, American Chemical Society (via EurekAlert)

8 comments
Bob Stuart
The real data point here is the clue that includes density - specific strength better than E-glass. If it was 20% better, they'd have said S-glass. I guess they couldn't brag about toughness.
clay
Fascinating.
Are you going to write a more detailed follow up soon?
Wood fibres are absolutely amazing. Like how redwoods are able to move water so high.
And now maybe wood based structural textiles are on the horizon.
You are gonna make me go look up gigapascals to convert them to psi now. :-) and tensile stiffness? I thought tensile is "stretching or pulling force".
Looking forward to more regarding this one!
EH
1.57 GPa = 228kpsi, comparable to the best heat-treated steel and better than most metals but much lighter
The tensile modulus (stiffness) of nanocellulose fibers is only about 1/3 that of standard carbon fiber and 1/10th that of the stiffest carbon fiber, but possibly much cheaper.
In strength and stiffness nanocellulose fiber performs very close to standard E-glass fiberglass or basalt fibers, and will likely be much more expensive for some time to come. It may have advantages in toughness and bonding in composites, but that remains to be seen.
notarichman
no indication on how easily these fibers can be manufactured? replace steel cables for suspension bridges with them? replace the spider silk cross hairs for rifle scopes? how about making 2D sheets and 3D honey comb shapes with the material? how do they handle shock waves? Heat? Cold? let's have some more material science testing!
DavidB
How can something developed by researchers at the KTH Royal Institute of Technology" be (much less win a prize for being) the strongest "natural biomaterial"?
That's like saying cars are the fastest horses.
"The researchers used a flow-assisted assembly technique that involved suspending nanofibers in water, in channels just 1 mm wide. Deionized and low pH water flows through, which helps the CNFs align in the right direction and self-organize into tightly-packed bundles."
Does that sound "natural" to anyone else?
Fretting Freddy the Ferret pressing the Fret
Does it matter that it's not "natural"? It's still made of the same stuff as wood and doesn't sound much chemicals are involved other than water.
Martin Hone
I agree DavidB. Good see the adaption of natural product and improving it, but why muddy the waters by claiming this 'bio-based ' product be be stronger than the leading natural fibre, spider silk ?
HoppyHopkins
sounds like the combination of this and the other two wood based materials would make some very light weight level 4 plus body armor for our military and police which would provide total body protection