August 23, 2016

Here comes Transparent Wood

Here comes Transparent Wood

See-through wood may become a building material of the future. Photo Credit: University of Maryland

Wood is a versatile material: it’s strong and it’s light and it’s flexible. But it isn’t translucent or particularly durable. Glass is. But glass isn’t strong or flexible. But what it you could get the better of both worlds by making wood transparent like glass?

A flight of fancy, you say? Drum rolls please!

A team of scientists at the University of Maryland, in the United States, has developed a process that can make wood stronger and more durable … and also translucent. And that makes their revamped wood an eminently desirable building material. Unlike glass, it’s a good thermal insulator but like glass it is optically transparent.

The see-through wood can create a uniform and consistent daylight distribution all day long without glare effect. It also offers “high-impact energy absorption that eliminates the safety issues often presented by glass.” In fact, the engineers have demonstrated the resilience of their product by hitting a piece of it with a hammer. The translucent wood withstood the impact while a similarly sized piece of glass immediately shattered.

But how did the scientists create a translucent piece of wood? Glad you’ve asked. They bleached a piece of wood by soaking it in sodium hydroxide (commonly known as lye) to remove lignin, a compound that turns wood strong and gives it its brown color. They then soaked it in a “clear liquid” before soaking the thus-clarified wood again, this time in a glue-like epoxy that makes it very hard and clear.

Once that is done, the porous tubes of cellulose within wood, which serve to suck water up from roots towards leaves and pull sugars down towards roots, into effective light diffusers. “You have a uniform consistent indoor lighting, which is independent of where the sun is,” one of the scientists explains. That means that even light from a glancing angle illuminates the see-through wood.

Why does all this matter? Because “Our transparent wood also has a much lower thermal conductivity compared with glass, making it a better thermally insulating building material with a lower carbon footprint,” they say.

But there’s a downside. “Making transparent wood requires using epoxy, so it’s not very environmentally friendly right now,” one researcher said. The scientists are now “experimenting with other types of clear stiffeners, which will include PVP (polyvinylphenol), which is recyclable.”



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