This is 'nanowood,' an invention that could reduce humanity's carbon footprint

March 12, 2018 by Amina Khan, Los Angeles Times
Completely derived from natural wood, nanowood with hierarchically aligned cellulose nanofibrils can be used as an anisotropic super thermal insulator. (A) Schematics of the thermally insulating properties of the nanowood. (B) Digital photograph of the nanowood and the corresponding properties beneficial for building insulation applications. Credit: Science Advances (2018). DOI: 10.1126/sciadv.aar3724

Scientists have designed a heat-insulating material made from wood that is both light and strong and made entirely from tiny, stripped-down wood fibers.

The so-called nanowood, described in the journal Science Advances, could one day be used to make more energy-efficient buildings. It's cheap and biodegradable, too.

"Nature is producing this kind of material," said senior author Liangbing Hu, a scientist and engineer at the University of Maryland in College Park.

Managing heat is a major issue in the cities we build. It's hard to keep heat indoors in the winter and keep it outdoors in the summer. The currently in use are often very expensive to make, both in terms of money and of energy. They're not usually biodegradable and ultimately contribute to our growing landfills. So scientists have been trying to come up with cheaper, more environmentally friendly options.

Hu has been probing the properties of nanocellulose, nanometer-scale versions of cellulose, the tough carbohydrate in the cell walls of plants that allows tree trunks to grow strong and tall. At these incredibly small scales, can take on remarkable characteristics, including a strength-to-weight ratio that's about eight times that of steel.

Hu and his team have already developed a strong, dense material they called super wood, in part by removing some of the wood's lignin—a complex polymer that holds cellulose in the wood together, almost like glue—and hemicellulose, another component of woody tissue.

But for this project, Hu and his colleagues removed all of the lignin and most of the hemicellulose. Lignin is very good at conducting heat—which means it would be a terrible insulator. Without all that lignin, the woody material turned pure white, allowing it to reflect incoming light rather than absorb it (which also helps to block heat).

The secret to nanowood's insulating powers lies partly in its structure. Styrofoam is isotropic: It basically looks the same from any angle. But nanowood is anisotropic: The fibers are bundled together in parallel, so it looks very different from different angles. Heat can travel up and down the fibers with ease, but can't easily cross them, particularly because of the air gaps left after all the woody filler (lignin and hemicellulose) was removed.

The scientists found that the nanowood was just as good an insulator as Styrofoam—slightly better, even. It far outclassed other materials, too.

On top of that, the nanowood was also lightweight and could withstand pressures of 13 megapascals. That's about 50 times higher than insulators like cellulose foam and more than 30 times higher than the strongest of the commercially-used thermal insulation materials, they said.

"To the best of our knowledge, the strength of our nanowood represents the highest value among available super insulating materials," the study authors wrote.

Even better, nanocellulose is readily available and relatively cheap to process, potentially costing as little as $7.44 per square meter. (The key to keeping it sustainable, Hu added, would be to harvest fast-growing trees like balsa, and leave slow-growing trees alone.) In the right conditions, bacteria can eat it, making it biodegradable.

"When the thickness is less than 1 mm, the nanowood slice can be rolled and folded, making it suitable for scenarios that require flexibility, such as pipelines in chemical factories and power plants," the authors wrote.

Hu said that such a strong, lightweight, thermally insulating could have a host of future uses. It could be used to build skyscrapers, to manufacture cars, even protect heat-sensitive electronics, whether on Earth or in space.

Explore further: New process could make wood as strong as titanium alloys but lighter and cheaper

More information: Tian Li et al. Anisotropic, lightweight, strong, and super thermally insulating nanowood with naturally aligned nanocellulose, Science Advances (2018). DOI: 10.1126/sciadv.aar3724

Related Stories

Carbon fiber from wood is used to build car

February 9, 2016

Remember wood paneled station wagons? Well, wood is back, but this time it's not for aesthetics—it's for reducing vehicle weight with renewable materials. Swedish researchers have just produced the world's first model car ...

Insulating bricks with microscopic bubbles

January 16, 2018

The better a building is insulated, the less heat is lost in winter—and the less energy is needed to achieve a comfortable room temperature. The Swiss Federal Office of Energy (SFOE) regularly raises the requirements for ...

Recommended for you

11 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Guy_Underbridge
not rated yet Mar 12, 2018
'Nanowood': Great idea but you got to change that name.
Bart_A
not rated yet Mar 12, 2018
Said someone after the skyscraper fell down: "the bacteria ate it."
TheGhostofOtto1923
2.3 / 5 (3) Mar 12, 2018
Said someone after the skyscraper fell down: "the bacteria ate it."
It wasn't bugs.

"5 But the Lord came down to see the city and the tower the people were building. 6 The Lord said, "If as one people speaking the same language they have begun to do this, then nothing they plan to do will be impossible for them. 7 Come, let us go down and confuse their language so they will not understand each other." gen11

Funny the similarity between Babel in the book, and the name of the book itself.

Coincidence or inside joke?
Nik_2213
5 / 5 (4) Mar 12, 2018
Um, if this stuff wicks damp, how quickly will mould / fungi eat it ? You may have to soak nanowood with eg PEG to stabilise it, treat the outside with char-type fire suppressant...
mackita
not rated yet Mar 12, 2018
The 12 mm × 30 mm × 120 mm sample of American basswood was cut along the growth direction, treated with a mixture of NaOH and Na2SO3 heated to boiling temperatures, followed by subsequent treatment with H2O2 to remove the lignin and most of the hemicellulose from the natural wood and the sample is subsequently freeze-dried to preserve the nanoporous structure of the delignified wood
. I'm not sure what I should think about it, because despite the pile of expert sounding stuff this study is very trivial and everyone could replicate it in his kitchen. They did use exactly the same process in which paper pulp is industrially produced except that last freeze-drying step. The resulting material has appearance and strength of balsa wood. Its structure would be probably destroyed by soaking or humidity.
Turgent
not rated yet Mar 12, 2018
This sounds like the all singing and dancing material.

Time to build new mosquito (British WWII multi use aircraft built of wood that was faster than all others) airplanes and derivatives.

"Even better, nanocellulose is readily available and relatively cheap to process, potentially costing as little as $7.44 per square meter."

"Even better, nanocellulose is readily available and relatively cheap to process, potentially costing as little as $7.44 per square meter." Note thickness is absent. Assuming elastic properties are acceptable and it is machinable this sounds like a disruptive technology if true
mackita
not rated yet Mar 12, 2018
This guy did use essentially the same process and finally he soaked the result by epoxy resin, so he got transparent "wood" at the end.
mackita
1 / 5 (1) Mar 12, 2018
assuming elastic properties are acceptable and it is machinable this sounds like a disruptive technology if true
I'm not sure about its actual usage. Every cellulose mill already produces such a "nanowood" in large quantities, except that it makes free cellulose fibers from it at the end from good reasons. There is also no advantage for usage the byproduct over the wood in construction industry. It just seems for me, that Chinese living in the USA learned how to penetrate into high impacted Science journal with fancy and environmentally well sounding ("nanowood") but otherwise completely dull and void study, which could be generated at every secondary school.
rrwillsj
1 / 5 (1) Mar 12, 2018
"Be Afraid. Very Afraid!" "The Chinese are being innovative. How dare they! Jeez, grow-op guys.

Remember Japan Inc? Or the Brits buying up all the American heiresses? We Yankee Sharps have been swindling the gullible foreigners for centuries now. Why do you think the Russian economy is teetering so? They are way over-extended buying into worthless properties.

USA! USA! Soolldd Amerhikhan!

If my understanding of this article is correct? The procedures for processing wood into nanowood, removes the flammable and heat-carrying lignin? And the hemicellulose. So it won't burn but reflects heat?

I did not see where it covered the issues of water-resistance. After being processed into nanowood, will there be any nutrients left for fungi? And for that matter, how about resistance to boring worms, wood ants and termites?

After all, this is the termite's planet. We Crazy Apes are just temporary renters. Might want to reconsider pissing off the landlords!
Dug
not rated yet Mar 12, 2018
Unfortunately, "biodegradable" limits product to only very short term uses such as disposable insulating packing materials. Being ashort term biodegradable material would seem to give away all of the carbon sequestering value such a product might have. Perhaps it's a stronger form of cardboard.

In order to be considered as a valuable building material the "biodegradable" nature of the material would have to go away. To do this you would probably be using a petrochemical derivative - not to mention the fossil fuels used in the processing of the cellulose.

Somewhere along the way - the "environmental" benefits (are lost) and costs of nanowood (are greater than) growing sustainable and carbon sequestering forests for lumber is probably a better overall environmental option. Seems to be a solution looking for a problem that might not really exist when you consider only short term carbon capture benefits.
rrwillsj
3 / 5 (2) Mar 13, 2018
Dug, your points seem reasonable. However, among the advantages of new products such as nanowood are diversity.

That the construction industry for one, would have more choices in materials to use. Maybe mix & match.

For the United States and Canada, the great percentage of buildings, especially personal residences, are built of wood. Resulting in a high social cost dealing with the inevitable house-fires.

Another common problem is infestation with vermin and molds. Those costs should include diseases spread by vermin. And medical costs of accumulating physical reactions to chemical poisons.

Obviously, there is no perfection. We will always have to settle for incremental improvements.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.