Who would have thought to combine wood pulp and dried-up exotic sea creatures? Researchers at the National Institute of Standards and Technology (NIST), and they were smart for doing so.
The marine tunicate, an exotic sea invertebrate often used in Asian cuisine, has been combined with wood pulp to form a new composite material that's flexible, sustainable, non-toxic, and UV light-reflective, says NIST. The material could be used in construction, food packaging, biomedical devices, cars, trucks, and boats, say researchers.
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ARTICLE New 'super wood' is ten times stronger, could replace steel say scientists University of Maryland (UMD) scientists have named it "super wood" and rightfully so, as they say it is over 10 times stronger and tougher than regular wood. |
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Scientists first remove the wood's lignin with acid, in a similar fashion to the University of Maryland's Super Wood, which then creates a milky solution. That solution ultimately dries to form a new material with a 'Bouligand' structure - a structure in which molecules stack up into twisted and spiral shapes. Those structures are resistant to cracking, but remained ultimately weak and unable to hold much weight.
Until now.
The NIST team hypothesized that combining the short wood-derived nano-cellulose rods with another natural material with longer crystalline rods would result in something new that would be incredibly strong and flexible. With appropriate additives, this new material could be used to create films that could slow down the diffusion of water and oxygen. That's where tunicates, whose inner structures are made of long, highly-crystalline nano-cellulose, come in.
"Tunicates have stuck out as the gold standard for their physical properties," said Johan Foster from Virginia Tech University, who is one of only a handful of teams working on tunicate harvest and research around the globe. Foster gathered and supplied the tunicates for the NIST project from a dock in Western France, where the animals are considered a nuisance species.
"If you put a little tunicate into the wood pulp composite, it makes it a little stiffer, and it doesn't break as quickly and becomes more flexible," said lead author Bharath Natarajan said. "Put in 10 percent and it's twice as strong. If your mixture is 30 percent tunicate and 70 percent wood pulp, the resulting composite is 15-20 times tougher. But after that, you really don't see an improvement in strength, and there is a reduction in toughness."
Tunicates are plentiful, but remain expensive to process, say researchers, so knowing exactly how much to add is key to scaling up their use in the future, and for keeping any resulting products affordable.
The NIST team plans on running further tests on the pulp-tunicate mix, which could be made to manufacture resilient, flexible and UV-reflective composites for use in sustainable, lightweight automobiles and aerospace vehicles, among other products.
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