Ordinary wood made stronger than steel or titanium

Wood is great stuff for ... everything. From it do everything that you can imagine. The only thing missing is strength. Many types of wood are very durable, but unfortunately not strong enough to be used more widely. Specialists from the United States achieved an increase in the strength characteristics of wood by special processing.

After a tree is processed by a new method, its strength increases tenfold, it becomes more durable than steel or titanium. At the same time, wood is still environmentally friendly material, an alternative to plastics or metals.

“In fact, this is a new class of materials with great potential,” said Lee Teng, a specialist from the University of Maryland. The work of Teng and his colleagues was published on February 7 in the authoritative scientific publication Nature.

Attempts to strengthen the tree, to change in one way or another, its characteristics have not ceased for decades . Some methods are successful, others are not. Microfibers of cellulose can be attributed to the number of successful ones, which makes it possible to create materials that are sufficiently resistant to external influences.

But Teng and his colleagues decided to approach the problem from the other side. Researchers have focused on modifying the porous structure of natural wood. Initially, they began to try to boil various types of wood, including oak, in a solution of sodium hydroxide and sodium sulfite for seven hours. This process left the pulp structure almost intact, but the components surrounding the pulp were partially gone. One of these components is lignin, a cellulose-binding polymer.

Then the team placed a wooden block under the press for a day, at the same time heating it to 100 degrees Celsius. As a result, wooden strips having a thickness of one fifth of the previous parameters were formed. In addition, this material was three times denser than natural wood and 11.5 times stronger. Previous attempts to strengthen the strength characteristics led to an increase in this parameter by a maximum of 3-4 times.

Scanning the fibers of a new material with an electron microscope showed that squeezing destroyed the cellulose tubes, which are compressed and intertwined. "You get nanofibres placed along the tree's growth axis, linked together," said one of the research participants.

In order to test how stable the “new type of wood” is to external factors, the team began to shoot at pallets from a ballistic gun, which is usually used to test the strength of military vehicles. As it turned out, the modified wood withstands the impact of a 46-gram steel projectile, flying at a speed of about 30 meters per second.

This, of course, is much slower than the speed of a bullet ejected from the barrel of a firearm, but it is still a solid achievement. This speed roughly corresponds to the speed of a car moving before a collision with an obstacle. Yes, Americans believe that their method allows you to create material suitable for the automotive industry.


Experts believe that the team of "tree improvers" overly complicates the process, which can be much simpler. For example, just exposure to high temperature, steam and pressure can significantly improve the strength characteristics of the material. And you can simply boil the wood for 7 hours in a solution of caustic soda. The result is a fairly durable material. 24-layer protection from such a tree delays a 9-mm bullet, which is fired from a pistol.

Michaela Ider, a researcher at the Max-Planck Institute, believes that pressure also strengthens wood - although in this case it is not clear how strongly the interweaving of nanofibers is. Nevertheless, the authors of the original work are confident that only their method allows to repeatedly improve the strength of wood. Colleagues agree with them, saying that the work has a great potential, and in the future it would be possible to create a commercial technology for the production of durable wooden building materials.