New process endows wood with super properties

December 31, 2018 | 06:55
Thinner but tougher and stronger.
Thinner but tougher and stronger.
University of Maryland (UMD) engineers, College Park have developed a process that makes wood more than ten times stronger and tougher than has been achieved by any process to date. Wood is a natural and sustainable material and this new process converts it into a new light structural material which is stronger than many titanium alloys.

The new wood ‘densification’ treatment makes a material twelve times stronger than natural wood and ten times tougher. The properties of the treated wood make it similar to carbon fibre, but much cheaper and a competitor to steel or even titanium alloys.

The treated wood is both strong and tough - a combination not normally found in nature. After measuring the mechanical properties of the densified wood, it was found to be as strong as steel but six times lighter. Ten times more energy is needed to break the material compared to natural wood. The densified wood can also be bent or formed into a shape in the course of the treatment process. During development, sheets of the new densified wood material were subjected to ballistic testing and partially resisted total projectile penetration whereas untreated wood provided little resistance.

The wood-densification treatment is a relatively simple technique and can be used with different types of wood. The two-stage process produces a material of exceptionally high strength, going far beyond anything previously achievable using wood as a raw material. Wood lignin acts as an adhesive between the cells in wood and the process removes some of this from the structure to achieve an optimal concentration level. Higher or lower concentrations significantly reduce the strength of the finished material. There seems to be a subtle balance between hydrogen bonding and the adhesion provided by the polyphenolic compounds, resulting in increased strength and toughness, it’s unusual to find both these properties are enhanced, they usually trade-off.

More details of the research can be found in the paper published in the journal Nature. These novel wood-based technologies have a commercial outlet via Inventwood LLC which is a UMD spinoff company.
 
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