Super strong wood through self-densifying

While sustainably-grown wood can be an economical and eco-friendly building material, its relatively low tensile strength limits its potential applications. That could soon change, however, thanks to a new self-densifying technique for creating super-strong wood.

Individual wood fibres are made up mainly of cellulose, along with a binder material known as lignin. This mixture forms the wall of what is essentially a long hollow tube – the fibre – which runs lengthwise within the larger piece of wood. The hollow space inside the tube is called the lumen, and it is this that limits wood’s strength.

A team from China’s Nanjing University recently set out to address that shortcoming, by developing the new process.  It begins by boiling a block of wood in a mixture of sodium hydroxide (lye) and sodium sulfite, removing some of the lignin. That block is then immersed in a heated blend of lithium chloride salt and a solvent known as dimethylacetamide. This causes the cellulose (and remaining lignin) to swell, expanding inwards to fill the lumen.

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Source: New Atlas
Image credit: Nanjing University