Associate Professor Liangbing Hu (L) and Professor Teng Li of the University of Maryland compare a piece of compressed wood (Top, C) to its original form (Bottom, C) at the University of Maryland, Maryland, the United States, on Feb. 2, 2018.(Xinhua/Hua Xie)
U.S. researchers said Wednesday that they have developed a simple way to make wood as strong as steel or even titanium alloys, opening up possible applications in areas such as buildings, cars and airplanes.
"This new way to treat wood makes it 12 times stronger than natural wood and 10 times tougher," associate professor Liangbing Hu of the University of Maryland, who led the study, said in a statement.
"This could be a competitor to steel or even titanium alloys, it is so strong and durable. It's also comparable to carbon fiber, but much less expensive," Hu said.
The process begins by removing the wood's lignin, the part of the wood that makes it both rigid and brown in color, according to the study published Wednesday in British journal Nature.
Then it is compressed at temperatures of 100 degrees Celsius for about one day, which makes the wood five times thinner than its original size.
Any defects like holes or knots are crushed together, the researchers explained.
The treatment process was extended a little further with a coat of paint.
"The wood's fibers are pressed together so tightly that they can form strong hydrogen bonds, like a crowd of people who can't budge -- who are also holding hands," they said.
Professor Teng Li, also with the University of Maryland, who co-led the study, measured the dense wood's mechanical properties and found it's 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," Li told Xinhua.
The team also tested the material by shooting a bullet-like projectile at it.
Unlike natural wood, which was blown straight through, the fully treated wood actually stopped the projectile partway through.
"The paper provides a highly promising route to the design of light weight high performance structural materials, with tremendous potential for a broad range of applications where high strength, large toughness and superior ballistic resistance are desired," said Huajian Gao, a professor at Brown University, who was not involved in the study.
"It is particularly exciting to note that the method is versatile for various species of wood and fairly easy to implement," Gao said.
