Scientists have just made wood that is as strong as steel
There are many excellent reasons planes aren’t made out of wood, but one of these just got knocked down. A team of researchers at the University of Maryland (UMD) has managed to make wood that is 12 times tougher than regular wood, and literally has the strength of steel.
The team, led by Liangbing Hu, started by boiling samples of wood in a liquid mix of sodium hydroxide and sodium sulphide to partially remove hemicellulose and lignin, both important polymers in the formation of cell walls. Then, the team pressed the wood using heat compression, collapsing the cell walls completely and forming tightly-aligned cellulous nanofibers. What they were left with was a very dense piece of wood, 20% thinner than natural wood, but with strength you just wouldn’t believe.
To test this, the engineers fired bullet-like projectiles at the treated wood. While the bullets flew right through the unmodified material, the treated wood stopped the bullet from going all the way through.
“This new way to treat wood makes it 12 times stronger than natural wood and ten times tougher,” Hu said. “This could be a competitor to steel or even titanium alloys, it is so strong and durable. It’s also comparable to carbon fibre, but much less expensive.”
Better still, while it’s as strong as steel and takes ten times more energy to fracture than natural wood, it’s not as heavy, weighing six times less. Its applications are seemingly endless.
According to the researchers, the treated wood can be used in cars, aeroplanes and even buildings. Living in a city made out of dense wood would be interesting, to say the least. Applications like this could mean that fast-growing, softwoods like pine or balsa, first treated with the solution, would be a much greener, more environmentally-friendly solution than denser woods like teak which is used in furniture. Though, we shouldn’t get our hopes up just yet.
The whole process takes nearly two days to complete as the wood needs to be boiled in the solution for over seven hours and then compressed for an entire day. The engineers still need to find a way of scaling and speeding up the process before we see its practical application.
Hu is clearly wood’s strongest advocate, having previously developed an array of wood-based materials. So far, he’s developed sodium-ion batteries based on a composite of wood and leaves, transparent wood and even built burnt-wood water filters.