나무가 철보다 강할 수 있나?
Researchers say they have created a new super-material in the laboratory. They say it is stronger, lighter and costs less than steel.
But the new material is not a product of high technology or a metallic substance. It is wood.
Researchers Liangbing Hu and Teng Li are with the University of Maryland in the United States.
By using a few chemicals, heat and pressure, they have made wood three times denser and 10 times stronger. Hu says that means it can compete with some of the world’s strongest materials.
"We're interested in replacing steel and carbon fibers with strong wood structures," he said.
The process does not require any special raw, unprocessed material. Hu said that means the cost of the product will be relatively low. He added, "We can start with very cheap wood, and we can also start with very fancy, expensive wood. But in the end, ultimately we get very similar performance."
The researchers are calling their product "super wood." It is made by partially removing a natural polymer called lignin.
Hu explained that “lignin is like a binder to hold all the components together in natural wood. In our process, we found out to be able to densify the wood completely, we have to remove some of these binders."
Strong chemicals are put on the wood. The chemicals remove about half of its lignin. Then, after being left in extreme heat and pressurized for a day, the treated wood is ready. The researchers say the wood is strong enough to build automobiles, airplanes, wind turbines and more. A report on their findings was published in the journal Nature.
The researchers say super-strength wood would have less of an effect on the environment than the steel or other metals it could replace. However, their process is not pollution-free. It uses some of the same chemicals involved in making paper.
Researcher Teng Li says he and Hu are finding many new ways to use wood, including creating batteries and see-through wood and paper.
“Wood has been existing on Earth more than a million years. And human beings have been using wood for furniture, construction for more than 10 thousand years. And then the more we worked on this material, we realized, we have never fully exhausted the potential of this amazing material."
Other scientists are finding new uses for wood as well. Researchers in Sweden have reported making wood-based super-strong fibers for clothing and other materials.