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A Chemical Bath and a Hot-press Can Transform Wood Into a Material That is Stronger Than Steel, Researchers Find (nature.com)
The process, and others like it, could make the humble material an eco-friendly alternative to using plastics and metals in the manufacture of cars and buildings, Nature reported this week. From the report: "It's a new class of materials with great potential," says Li Teng, a mechanics specialist at the University of Maryland in College Park and a co-author of the study published on 7 February in Nature. Attempts to strengthen wood go back decades. Some efforts have focused on synthesizing new materials by extracting the nanofibres in cellulose -- the hard natural polymer in the tubular cells that funnel water through plant tissue. Li's team took a different approach: the researchers focused on modifying the porous structure of natural wood. First, they boiled different wood types, including oak, in a solution of sodium hydroxide and sodium sulfite for seven hours. That treatment left the starchy cellulose mostly intact, but created more hollow space in the wood structure by removing some of the surrounding compounds. These included lignin, a polymer that binds the cellulose. Then the team pressed the block -- like a panini sandwich -- at 100C (212F) for a day. The result: a wooden plank one-fifth the thickness, but three times the density of natural wood -- and 11.5 times stronger. Previous attempts to densify wood have improved the strength by a factor of about three to four.
There is also a summary here at Sciences News.
Ceci n'est pas une signature.
There's a reason you should have read the fucking article.
Hu says that his study’s main finding is that removing the right amount of lignin is key to maximizing performance. In his team’s experiments, removing too much of the polymer resulted in less-dense, brittle wood, suggesting that some leftover lignin is helpful in binding the cellulose fibres when they are hot-pressed. The wood was strongest when roughly 45% of the lignin was removed.
How isotropic? (a rope and a bucket of sand are both strong: but the rope is only strong in tension and the sand only in compression). What's the 'strength' to weight ratio?
For years we've been able to pump wood full of ethylene and then induce it to polymerize, What you end up with is a heavy piece of plastic inferior in almost all respects to the original wood.
As you point out, cost of working, preservation, reaction with the environment: all of these are hugely important.
Mild steel is US$500 per ton; Al is US$2000 per ton. It's the cheaper cost of manufacturing that means your beer can isn't steel any more.
Protoplasm. Quiet Protoplasm. I like quiet protoplasm.
You just invented plywood!
Plywood is weaker than normal wood not stronger and definitely not stronger than steel.
Not when sandwiched vertically in a weight-bearing truss.
Happiness in intelligent people is the rarest thing I know.
Ernest Hemingway
Steel and aluminum in particular are NOT "easily recycled" - in fact that's a much more expensive process than creating engineered wood of any type by a factor nearing 100x
To use a French term: bullshit. Recycling aluminum is as easy as tossing it into the furnace. Unless you're going to claim mining the bauxite, transporting it, refining it, THEN heating it into ingots is somehow less expensive than transporting flattened cans to a mill and dumping them in the furnace.
Oh wait, you don't have to make up more bullshit. Recycling scrap aluminium requires only 5% of the energy used to make new aluminium.
For steel, only 25% of the energy needed to process raw ore is needed to remelt steel.
Trabants were partially made of plywood, weren't they?
Yes. Also, many WW2-era German, Russian, and British aircraft of many types including fighters, especially early in the war for the Soviets and late in the war for the Germans, used various types of laminated and/or compressed wood, some as a major percentage of the vehicle. The British Mosquito was one of the fastest aircraft in the WW2 sky and made the first bombing runs on Berlin due to it's speed, payload capacity, long range, and was made largely from wood. It served many different roles from heavy fighter, to twin-engine fast bomber, to fast reconnaissance, and more. Pilots loved the "Mossy". It was such a great aircraft the Germans tried to copy it, but with only limited success.
Strat
Progressivism (aka US 'Liberalism'): Ideas so good they need a police/surveillance-state to enforce.
In WW2 the British built a multi-role military aircraft called the "Mosquito" out of plywood. Originally conceived as a very fast lightweight bomber, it was a brilliant success at a wide variety of tasks: night fighter, high altitude interceptor, ground attack craft, photo-reconnaissance craft, torpedo bomber.
Basically it was the anti-F35: designed to do one thing well, it ended up doing everything pretty well.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
The chassis of Morgan sports cars (just about all that remains of the UK owned car industry) are still made of ash.
Note that "strength" in this context is per cross sectional area. So taking a block of wood, and compressing it down doesn't change its absolute strength (it can support the same weight as before), but increases its measured strength (load per square mm of cross sectional area before failure). One of the attractions of metals like steel is their isotropic properties - they have the same properties regardless of which direction you load them. Fibrous materials are anisotropic - stronger in certain directions than others.
Glass fibers are also stronger than steel in tension, but they're weaker in compression and absolutely suck in shear (loading perpendicular to the fibers). The fibers just bend sideways instead of offering any resistance. So we embed them in a matrix of plastic (polyester or epoxy) to create fiberglass. Tensile and compressive strength are reduced, but shear strength improves substantially - enough to where you can walk on a fiberglass board whereas raw glass fibers would simply flop over and let you fall through. Where a fiber used to bend, the plastic matrix absorbs and transmits those forces to other fibers, converting shear forces into tension and compression (the board bows downward in the middle, compressing in the top half, stretching in the bottom half).
It sounds like what this team has done is taken wood, and cooked it so the cellulose fibers remain but much of the matrix which holds them together has been removed. That has little consequence in tension, but could weaken shear strength to where the material is structurally useless except as rope/cable.
Yes and no. The 2x4s used in standard residential framing burn quite readily. Larger timbers form a protective char, which, as long as it remains on the wood, protects the inner core from fire. If the timber has been specced correctly, the char does not penetrate deeply enough to compromise the structure for some time.
Steel, meanwhile, is an excellent heat conductor and therefore will start to sag as soon as the outer edge of the steel has reached a temperature that will cause sag.
Looks like the chassis is metal but the frame is ash:
https://www.classicdriver.com/...
An indication of just how good the Mosquito performed is the grudging admiration of Hermann Göring:
In 1940 I could at least fly as far as Glasgow in most of my aircraft, but not now! It makes me furious when I see the Mosquito. I turn green and yellow with envy. The British, who can afford aluminium better than we can, knock together a beautiful wooden aircraft that every piano factory over there is building, and they give it a speed which they have now increased yet again. What do you make of that? There is nothing the British do not have. They have the geniuses and we have the nincompoops. After the war is over I'm going to buy a British radio set – then at least I'll own something that has always worked.