Transparent Wood Becomes More Translucent Using A Bio-Plastic Made From Citrus

Researchers at KTH Royal Institute of Technology in Sweden have announced an improvement for their transparent wood first introduced five years ago. The new research has made their composite material 100 percent renewable and more translucent. Researchers have infused their transparent wood with a clear bio-plastic derived from citrus fruit.

The key to making wood into a transparent composite material is stripping out its lignin which is the light-absorbing component in wood. However, the pores left empty after stripping out the lignin have to be filled with something to restore the natural strength of the material and allow light to permeate. Previous versions of the material used fossil-based polymers.

Researchers have completed testing with an eco-friendly alternative called limonene acrylate, a monomer made from limonene. The material is made from renewable citrus, such as peel waste recycled from the orange juice industry. The composite offers optical transmittance of 90 percent at 1.2-millimeter thickness and a remarkably low haze of 30 percent.

The new material is intended for structural use and shows heavy-duty performance with a strength of 174 MPa and elasticity of 17 GPa while being sustainable. Researchers have been looking for a way to replace fossil-based polymers, and its replacement was seen as a key challenge to making sustainable transparent wood.

KTH's advances could allow the transparent wood to be used in a range of applications, including smart windows, wood for heat storage, wood that has integrated lighting function, and possibly a wooden laser. Currently, the researchers are working with the photonics group at KTH to explore the nanotechnology possibilities further. The improved material is made with no solvents, and only bio-derived chemicals are used.