According to new research conducted by an international team, an innovative, rapid ‘water-shock’ process can be used to create strong and mouldable wood.
The scientists behind the research say the flexible wood created through this process has enhanced mechanical properties that could make it a candidate for a whole new range of applications, which might even include aerospace!
Previous approaches to instilling timber with the same levels of malleability as metals and plastics have compromised the strength of the material. However, this new process has the potential to improve both strength and malleability, which would make timber a contender for a much broader range of applications.
So, how has this been achieved? The researchers first softened wood by extracting the lignin that binds its cell walls and is responsible for its strength. After closing the wood’s fibers through a process of evaporation, they proceeded to re-swell it by ‘shocking’ it with water.
By moulding the wood into the required shape before it dries, the finished timber product can be created to perfectly suit the spatial requirements of the end user.
“The rapid water-shock process forms a distinct, partially open, wrinkled cell wall structure that provides space for compression, as well as the ability to support high strain, allowing the material to be easily folded and moulded,” said Professor Liangbing Hu, Director of the Center of Materials Innovation at the University of Maryland, and lead author of the research report.
“The resulting 3D-moulded wood is six times stronger than the starting wood, and comparable to widely used lightweight materials like aluminum alloys.”
The processed wood created using this approach offers such high levels of formability thanks to the capacity of the wrinkled cell wall structure to withstand severe folding without fracture.
“The researchers introduce a clever means to transform the naturally occurring, straight-walled cellular structures of wood into wavy, accordion-like geometries, at the microscale,” said co-author Professor John Rogers, of Northwestern University.
“The result is an unusual, high-strength form of wood that is both flexible and mouldable, in ways that open up new applications for this very old class of material.”
Access to mouldable wood significantly increases the possibilities for potential use of timber as a sustainable structural material, particularly as industries look to reduce their environmental footprint.
“This out-of-the-box approach to developing advanced wood materials will drive wood product and market innovation as a sustainable solution to replace many unsustainable structural materials and combat climate change,” said the USDA Forest Products Lab’s JY Zhu, who was also involved in the research.
Co-author Stephen Eichhorn, Professor of Materials and Science Engineering at the University of Bristol, cited a childhood memory of his father building an aeroplane from wood as inspiration for one particularly exciting potential future use.
“He bent the wood to be used in the wings of the plane using steam. To see now that it is possible to make this flexible wood, while also enhancing the mechanical properties, makes this a truly amazing material. And who knows? It could be used as a future material in aerospace!” said Eichhorn.
The research was the result of a collaboration between the University of Maryland’s Center for Materials Innovation, Yale University, The Ohio State University, the University of North Texas, the US Department of Agriculture Forest Service, the University of Bristol, and ETH Zurich.
Source: Phys.org
