Posts Tagged ‘wood’


The new super compressed wood is nearly nine times stronger than its natural counterpart. (Photo: University of Maryland)

Researchers at the University of Maryland have re-designed wood to make it entirely impervious to visible light, while only absorbing the slightest levels of near-infrared light.

Rather than absorbing sunlight, the new wood could bounce it right back into the environment. In effect, homes made from this material would be able to prevent virtually all heat from seeping indoors, potentially easing our reliance on air conditioning in summer months.

“When applied to building, this game-changing structural material cools without the input of electricity or water,” noted Yao Zhai, one of the study authors, in a press release.

We know that air conditioning saves lives, especially in climates where heat takes a deadly toll on air quality. But we also know that as we dial up the AC, we also dial up demand on fossil fuel-burning power plants. And emissions from those plants stir up an atmospheric cocktail that can be just as toxic.

“Reducing human reliance on energy-inefficient cooling methods such as air conditioning would have a large impact on the global energy landscape,” the researchers note in the study abstract.

To make that kind of “cooling” wood, scientists used hydrogen peroxide to strip away the lignin, a support element in the cell walls of trees. That process exposed only the wood’s cellulose, which is a powerful building block of plants and trees. It’s also incredibly impervious to the sun’s energy.

What’s more, the lignin-free wood allows heat produced indoors to escape. That’s because indoor heat occupies a slightly different wavelength than your garden variety sunlight — a wavelength that doesn’t get repulsed by the new wood variant. So by day, the sun’s heat is kept at bay, and at night, indoor heat dissipates into the environment, although the team admits this could be an issue when it comes to actually retaining heat indoors.

Another benefit to wood made entirely of cellulose? It’s incredibly strong. In a previous study, researchers noted that cellulose nanofibers outperform steel and spider silk as the “strongest bio-material” on Earth.

The University of Maryland team claims the new wood packs a tensile strength of around 404 megapascals, or more than eight times that of natural wood. That puts it somewhere in the neighborhood of steel.

“Wood has been used for thousands of years and has emerged as an important sustainable building material to potentially replace steel and concrete because of its economic and environmental advantages,” the authors note.

https://www.mnn.com/green-tech/research-innovations/stories/cooling-wood-reflects-heat-sun?utm_source=Weekly+Newsletter&utm_campaign=9bbb9aca6f-RSS_EMAIL_CAMPAIGN_WED0529_2019&utm_medium=email&utm_term=0_fcbff2e256-9bbb9aca6f-40844241

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A new wood-compacting process crushes the gaps between cell walls in natural wood (porous structure seen in the scanning electron microscopy image, left), making the densified wood (right) as strong as steel.

Newly fabricated superstrong lumber gives a whole new meaning to “hardwood.”

This ultracompact wood, described in the Feb. 8 Nature, is created by boiling a wood block in a water-based solution of sodium hydroxide and sodium sulfite. The chemicals partially strip the wood of substances called lignin and hemicellulose, which help give wood its structure and rigidity. Then the block gets squeezed between metal plates heated to 100° Celsius at a pressure of 5 megapascals — about 50 times the pressure of sea-level atmosphere. That squashes the gaps between the cell walls in the wood, shrinking the block to about 20 percent its original thickness and making it three times denser.

Researchers found that the densified wood could withstand being stretched or pulled 11.5 times harder than its natural counterpart without breaking. That makes it about as strong as steel, even though it’s more lightweight. Stainless steel pellets fired from an air gun and moving at 30 meters per second easily busted through a typical wooden plank, but got lodged in a stack of densified wood sheets with the same total thickness.

Chemicals used to process the wood work for various tree species and don’t pose any significant pollution concerns, says study coauthor Teng Li, a mechanical engineer at the University of Maryland in College Park. So this condensed wood could provide an ecofriendly alternative to steels or alloys for constructing buildings or bridges. It could also be used to manufacture more lightweight, fuel-efficient cars or trains, Li says.

J. Song et al. Processing bulk natural wood into a high-performance structural material. Nature. Vol. 554, February 8, 2018, p. 224. doi: 10.1038/nature25476.

https://www.sciencenews.org/article/superdense-wood-lightweight-strong-steel