Researchers at the University of Maryland in the USA have developed a simple strategy to transform natural wood into a high-performance structural material with a more than tenfold increase in strength and toughness. The researchers, reporting their process today in Nature journal, say that this treatment also results in a material with greater dimensional stability that could be substituted into any application where steel is currently used, such as cars, aeroplanes, buildings and, presumably, bicycle manufacture.
We’ve reported on wooden bicycles many times in the past, but what’s different here is that the University of Maryland researchers, led by Liangbing Hu, are proposing that bulk natural wood is transformed using a two-step process that involves the partial removal of lignin and hemicellulose through boiling in an aqueous mixture of sodium hydroxide and sodium sulphite. The material is then mechanically hot-pressed at 100°C, leading to a reduction in thickness of about 80%.
According to the researchers, “[This leads] to the total collapse of cell walls and the complete densification of the natural wood with highly aligned cellulose nanofibres.”
This treatment is said to work equally effectively for various species of wood – both hard woods and cheap and fast growing soft woods – and results in a material that has a specific tensile strength that's higher than that of high-specific-strength steel (HSSS), and even of lightweight titanium alloy (Ti 6Al/4V).
"This could be a competitor to steel or even titanium alloys, it is so strong and durable," said Liangbing Hu. "It's also comparable to carbon fibre, but much less expensive."
“The large increase in tensile strength of the densified wood is not accompanied by a decrease in toughness,” say the researchers. “Both the work of fracture and the elastic stiffness of the densified wood are more than ten times higher than those of natural wood.”
Mat has worked for loads of bike magazines over 20+ years, and been editor of 220 Triathlon and Cycling Plus. He's been road.cc technical editor for eight years, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a past winner of the Cycling Media Award for Specialist Online Writer.