Engineers at the University of Maryland have found a way to make wood more than ten times stronger and tougher than before, creating a natural substance that is stronger than many titanium alloys. According to them this kind of wood could be used in cars, airplanes, buildings and any application where steel is used.
The team’s process begins by removing the wood’s lignin, the part of the wood that makes it both rigid and brown in colour. Then it is compressed under mild heat, at about 150 F. This causes the cellulose fibres to become very tightly packed. Any defects like holes or knots are crushed together. The treatment process was extended a little further with a coat of paint.
The scientists found that the wood’s fibres are pressed together so tightly that they can form strong hydrogen bonds, like a crowd of people who can’t budge. The compression makes the wood five times thinner than its original size.
The team tested their new wood material and natural wood by shooting bullet-like projectiles at it. The projectile blew straight through the natural wood. The fully treated wood stopped the projectile partway through.
“This new way to treat wood makes it twelve times stronger than natural wood and ten times tougher. This could be a competitor to steel or even titanium alloys because it is so strong and durable. It’s also comparable to carbon fibre, but much less expensive,” said Liangbing Hu, the leader of the team that did the research published in the journal Nature. Hu is an associate professor of materials science and engineering and a member of the Maryland Energy Innovation Institute.
Teng Li, the co-leader of the team and the Samuel P. Langley Professor of mechanical engineering at the University of Maryland, whose team measured the dense wood’s mechanical properties, said: “The wood is both strong and tough, which is a combination not usually found in nature. It is as strong as steel, but six times lighter. It takes 10 times more energy to fracture than natural wood. It can even be bent and molded at the beginning of the process.”
