An extract from orange juice production is offering an eco-friendly way for developing transparent wood, an innovative structural material for building construction. Since it was first introduced in 2016, transparent wood has been developed by researchers at KTH Royal Institute of Technology in Sweden. The wood lets natural light through and can store thermal energy.
The key to making wood into a transparent composite material is to strip out its lignin, the major light-absorbing component in wood. But the empty pores left behind by the absence of lignin need to be filled with something that restores the wood’s strength and allows light to permeate.
In earlier versions of the composite, researchers at KTH’s Wallenberg Wood Science Centre used fossil-based polymers. Now, the researchers have successfully tested an eco-friendly alternative: limonene acrylate. “The new limonene acrylate is made from renewable citrus, such as peel waste that can be recycled from the orange juice industry,” says KTH doctoral student Céline Montanari.
Unlike other transparent wood composites developed during the past five years, the material developed at KTH is intended for structural use. It shows heavy-duty mechanical performance.
All along, sustainability has been a priority for the research group, says Professor Lars Berglund, head of KTH’s Department of Fibre and Polymer Technology. “Replacing the fossil-based polymers has been one of the challenges we have had in making sustainable transparent wood,” Berglund says. Environmental considerations and so-called green chemistry permeate the entire work, he says. The material is made with no solvents, and all chemicals are derived from bio-based raw materials.
The new advances could enable a yet unexplored range of applications, such as in wood nanotechnology, Berglund says. Possibilities include smart windows, wood for heat-storage, wood that has built-in lighting function – even a wooden laser.
The research team is working with Sergei Popov’s photonics group at KTH to explore the nanotechnology possibilities even further.
Source: KTH Royal Institute of Technology
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