Using the legendary properties of heartwood from the black locust tree as their inspiration, scientists have discovered a way to improve the performance of softwoods widely used in construction. The method, reported in the journal ACS Applied Materials & Interfaces, involves addition of similar kinds of flavonoid compounds that boost the health of humans.
Ingo Burgert and colleagues explain that wood's position as a mainstay building material over the centuries results from a combination of desirable factors, including surprising strength for a material so light in weight. Wood is renewable and sustainable, making it even more attractive in the 21st century. Wood, however, has a major drawback that limits its use: It collects moisture easily -- warping, bending, twisting and rotting in ways that can undermine wooden structures. Some trees, like the black locust, deposit substances termed flavonoids into their less durable "sapwood." It changes sapwood into darker "heartwood" that reduces water collection and resists rot. The scientists used this process as an inspiration for trying an improved softwood that is more stable than natural wood.
They describe a process that incorporates flavonoids into the walls of the cells of spruce wood, a common building material for making houses and other products. The hydrophobic flavonoids are embedded in the more hydrophilic cell wall environment, meaning that the cell walls take in less water. Burgert and coworkers report that the treated wood was harder than untreated wood and more resistant to the effects of water, holding its shape better through changing humidity.
The authors acknowledge funding from the Max Planck Society, Germany, as well as the Bundesamt für Umweltschutz and Lignum, Switzerland.
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