A research group led by the University of Maryland in the United States has developed a process, by which several tree species can be strengthened to being bulletproof. A research report published in Nature magazine says that wooden boards made in the process match steel and some titanium alloys, when it comes to strength.
The manufacturing process of such wooden boards consists of two phases. The first stages are similar to making cellulose.
At the beginning of the process wood is boiled with sodium, which removes lignin and hemicellulose. This strengthens the cell walls of the wood.
In the second phase the processed wood is compressed, until the cell walls scatter. After that the pressed material is heated slightly. This increases the development of new chemical bonds, but at the same time maintains the polymers, which are important for wood’s density.
After these processes the wooden material is three times as dense as the unprocessed. Liangbing Hu, research scientist at the University of Maryland says, that the process makes wood 12 times stronger and ten times more solid than natural wood.
Wood’s compression strength can be made 50 times better, and it’s stiffness can be made almost 20 times better than the original, according to Liangbing Hu.
The material can be molded without restrictions, and it is supposed to withstand humidity. However, so far there is only one piece size of a book manufactured from the material.
According to researchers, wooden material could be used to make bullet proof armour plates. This kind of board does not protect from bullets as well as Kevlar, which is commonly used in bullet proof vests, but its manufacturing costs are only five percent of those of Kevlar.
There are also plans to use the wooden material in buildings and vehicles, and its possibilities are being researched constantly. For example, Lars Berglund’s research group in the Technical University of Stockholm (KHT) has developed wooden window screens of the material.