Fwd: [Dewayne-Net] Stronger Than Steel, Able to Stop a Speeding Bullet - It's Super Wood!

["Dave Farber" <farber () gmail com>]

Begin forwarded message:

> From: Dewayne Hendricks <dewayne () warpspeed com>
> Date: February 13, 2018 at 8:07:21 AM EST
> To: Multiple recipients of Dewayne-Net <dewayne-net () warpspeed com>
> Subject: [Dewayne-Net] Stronger Than Steel, Able to Stop a Speeding Bullet - It's Super Wood!
> Reply-To: dewayne-net () warpspeed com
>
> [Note:  This item comes from friend Steve Schear.  DLH]
>
> Stronger Than Steel, Able to Stop a Speeding Bullet—It’s Super Wood!
> Simple processes can make wood tough, impact-resistant—or even transparent
> By Sid Perkins
> Feb 7 2018
> <https://www.scientificamerican.com/article/stronger-than-steel-able-to-stop-a-speeding-bullet-mdash-it-rsquo-s-super-wood/>
>
> Some varieties of wood, such as oak and maple, are renowned for their strength. But scientists say a simple and 
> inexpensive new process can transform any type of wood into a material stronger than steel, and even some high-tech 
> titanium alloys. Besides taking a star turn in buildings and vehicles, the substance could even be used to make 
> bullet-resistant armor plates.
>
> Wood is abundant and relatively low-cost—it literally grows on trees. And although it has been used for millennia to 
> build everything from furniture to homes and larger structures, untreated wood is rarely as strong as metals used in 
> construction. Researchers have long tried to enhance its strength, especially by compressing and “densifying” it, 
> says Liangbing Hu, a materials scientist at the University of Maryland, College Park. But densified wood tends to 
> weaken and spring back toward its original size and shape, especially in humid conditions.
>
> Now, Hu and his colleagues say they have come up with a better way to densify wood, which they report in the February 
> 7 Nature. Their simple, two-step process starts with boiling wood in a solution of sodium hydroxide (NaOH) and sodium 
> sulfite (Na2SO3), a chemical treatment similar to the first step in creating the wood pulp used to make paper. This 
> partially removes lignin and hemicellulose (natural polymers that help stiffen a plant’s cell walls)—but it largely 
> leaves the wood’s cellulose (another natural polymer) intact, Hu says.
>
> The second step is almost as simple as the first: Compressing the treated wood until its cell walls collapse, then 
> maintaining that compression as it is gently heated. The pressure and heat encourage the formation of chemical bonds 
> between large numbers of hydrogen atoms and neighboring atoms in adjacent nanofibers of cellulose, greatly 
> strengthening the material.
>
> The results are impressive. The team’s compressed wood is three times as dense as the untreated substance, Hu says, 
> adding that its resistance to being ripped apart is increased more than 10-fold. It also can become about 50 times 
> more resistant to compression and almost 20 times as stiff. The densified wood is also substantially harder, more 
> scratch-resistant and more impact-resistant. It can be molded into almost any shape. Perhaps most importantly, the 
> densified wood is also moisture-resistant: In lab tests, compressed samples exposed to extreme humidity for more than 
> five days swelled less than 10 percent—and in subsequent tests, Hu says, a simple coat of paint eliminated that 
> swelling entirely.
>
> A five-layer, plywoodlike sandwich of densified wood stopped simulated bullets fired into the material—a result Hu 
> and his colleagues suggest could lead to low-cost armor. The material does not protect quite as well as a Kevlar 
> sheet of the same thickness—but it only costs about 5 percent as much, he notes.
>
> The team’s results “appear to open the door to a new class of lightweight materials,” says Ping Liu, a materials 
> chemist at the University of California, San Diego, unaffiliated with the Nature study. Vehicle manufacturers have 
> often tried to save weight by switching from regular steel to high-strength steel, aluminum alloys or carbon-fiber 
> composites—but those materials are costly, and consumers “rarely make that money back in fuel savings,” Liu says. And 
> densified wood has another leg up on carbon-fiber composites: It does not require expensive adhesives that also can 
> make components difficult, if not impossible, to recycle.
>
> [snip]
>
> Dewayne-Net RSS Feed: http://dewaynenet.wordpress.com/feed/
> Twitter: https://twitter.com/wa8dzp



-------------------------------------------
Archives: https://www.listbox.com/member/archive/247/=now
RSS Feed: https://www.listbox.com/member/archive/rss/247/18849915-ae8fa580
Modify Your Subscription: https://www.listbox.com/member/?member_id=18849915&id_secret=18849915-aa268125
Unsubscribe Now: 
https://www.listbox.com/unsubscribe/?member_id=18849915&id_secret=18849915-32545cb4&post_id=20180213101704:EF37F40A-10D0-11E8-B311-C8936133EBD3
Powered by Listbox: http://www.listbox.com