Wood: building block of the future

Engineers at the University of Maryland have found a way to make wood more than 10 times stronger and tougher than before, creating a natural substance that is stronger than many titanium alloys.

“It is both strong and tough, which is a combination not usually found in nature,” says team leader Teng Li, professor of mechanical engineering at the university.

“It is as strong as steel, but six times lighter, and takes ten times more energy to fracture than natural wood. It can even be bent and moulded at the beginning of the process.”

The team’s process begins by removing the wood’s lignin, which is the part of the wood that makes it both rigid and brown in colour. It is then compressed under mild heat, at about 65°C. This causes the cellulose fibers to become very tightly packed. Any defects like holes or knots are crushed together, and the treatment process was extended a little further with a coat of paint.

The scientists found that 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. The compression makes the wood five times thinner than its original size.

“Soft woods like pine or balsa, which grow fast and are more environmentally friendly, could replace slower-growing but denser woods like teak, in furniture or buildings,” says Liangbing Hu, leader of the team that conducted the research.

“This kind of wood could be used in cars, airplanes, buildings – any application where steel is used."

Image: University of Maryland