Researchers at the Swedish KTH Royal Institute of Technology developed the first transparent wood without the need for fossil-based materials that is 100% renewable.

A lot is happening in the world of transparent wood. Back in February, we reported on a project by the University of Maryland (USA) that made transparent wood using less chemicals and solar power. However, this project, like an earlier version of transparent wood by KTH, used fossil-based polymers to reinforce the material.

To make wood transparent, the material has to be stripped of its lignin, which is the major light-absorbing component in wood. The empty pores left behind have to be filled with something that restores the wood’s strength and allows light to permeate.

The researchers found an eco-friendly alternative to fossil-based polymers in limonene acrylate, a monomer made from limonene, which is a major component in the oil of citrus fruit peels. The monomer can be extracted from peels, for instance waste from the orange juice industry.

The new composite offers optical transmittance of 90 per cent at 1.2 mm thickness. It was developed for structural use, unlike earlier versions. It shows heavy-duty mechanical performance: with a strength of 174 MPa (25.2 ksi) and elasticity of 17 GPa (or about 2.5 Mpsi).

The material is made without any solvents and all chemicals are derived from bio-based raw materials.

Photos: Céline Montanari / KTH Royal Institute of Technology