Engineers from the University of Maryland (UMD) have found a way to treat the wood that makes it so strong and resilient as to overcome many titanium alloys. “This new way of treating the wood makes it 12 times more resistant than natural wood and 10 times tougher,” said Liangbing Hu of the School of Engineering, A. James Clark of UMD and the leader of the team that conducted the research, which is published in Nature.
“This could compete with the steel or even titanium alloys, for being so strong and durable. It is also comparable to the carbon fiber, but much less costly.” Hu is an associate professor of science and materials engineering and a member of the Maryland Energy Innovation Institute.
“It is strong and tough, a combination that is not normally found in nature,” said Teng Li, co-director of the team and Samuel P. Langley, an associate professor of mechanical engineering in the school of Clark from the UMD. His team measured the mechanical properties of the wood dense. “It’s as strong as steel, but six times lighter. It takes 10 times more energy to fracturarla the natural wood. You can even bend it and shape it at the beginning of the process.”
The team also tested the new material of natural wood by shooting projectiles similar to bullets. The projectile made a direct hit through the natural wood. The wood is completely treated stopped the projectile until the half.
“Soft woods such as pine, which grow fast and are more environmentally friendly, could replace woods of slower growth but more dense, like teak furniture or buildings,” said Hu.
“The document provides a route very promising for the design of structural materials with lightweight, high-performance, with a tremendous potential for a wide range of applications where you want high strength, high hardness and ballistic resistance higher,” said Huajian Gao, professor, Brown University, who was not involved in the study. “It is particularly exciting to observe that the method is versatile for various species of wood and fairly easy to implement”.
“This type of wood could be used in cars, aircraft, buildings, any application that uses steel,” said Hu.
“The two-step process reported in this paper reaches a force exceptionally high, far beyond what is reported in the literature,” said Zhigang Suo, professor of mechanics and materials at Harvard University, who also participated in the study. “Given the abundance of wood, as well as other plants rich in cellulose, this study inspires the imagination”.
“The observation most prominently, in my opinion, is the existence of a limit concentration of lignin, the glue between the cells of wood, to maximize the mechanical performance of the densified wood. Removing too much or too little reduces the resistance in comparison with a maximum value achieved in the elimination intermediate or partial lignin. This reveals the subtle balance between the hydrogen bonds and the adhesion imparted by this polyphenolic compound. In addition, of note is the fact that the densification of wood leads to both, higher strength and toughness, two properties that are generally offset each other,” said Orlando J. Rojas, professor at the University of Aalto in Finland. That magic number would be around 45%.