The wood may seem more appropriate for a cozy house than for modern architecture, however, a specially treated type of wood can become a fashionable building material of tomorrow. Scientists report the development of a new type of transparent wood, which not only transmits light but also absorbs and emits heat, which in theory could reduce the energy costs. This material can withstand heavy loads and decomposes over time — important characteristics in the modern world.
Transparent wood: material of the future?
“In 2016, we have shown that transparent wood has excellent thermal insulation properties in comparison with glass and also high light transmittance,” says Celine Montanari, who presented their project. “In this work we tried to reduce the building’s energy consumption by introducing a material that can absorb, store and release heat”.
With the development of economy worldwide, the energy consumption is constantly growing. Most of this energy is used for lighting, heating and cooling homes, offices and other buildings. Glass window can transmit light, contributing to light and heat homes, but they do not accumulate energy, which can be used after sunset.
Three years ago, lead researcher Lars, Berglund from the Royal Institute of technology in Stockholm, Sweden, announced the creation of optically transparent wood in the journal biomacromolecules is. The scientists made the material by removing the light-absorbing component of the lignin from the cell wall of balsa wood. To reduce the scattering of light, and they included acrylic in the porous wood structure. The team could see through the material, but it was quite muddy, to provide privacy in the construction of large objects. Transparent wood also has a pleasant mechanical properties that allow it to withstand heavy loads.
Based on this work, Montanari and Berglund added a polymer called polyethylene glycol (PEG) to delignification wood. They chose PEG because of its sposobnosti to accumulate heat, but also because of the similar wood properties. In Stockholm there is a very old ship called “Vasa”, and informed the researchers used a PEG to stabilize the craft wood — PEG can penetrate deeply into the cells of the wood.
PEG is considered to be a material with change of phase, being stable in normal condition, it begins to melt at a temperature of 26 degrees, releasing energy in the process. The melting point can be adjusted by using different types of PEG. “On a Sunny day, the material will absorb the heat before it gets inside, and inside is cooler than outside. Night the opposite happens: PEG will solidify and release the heat in the room, so the temperature will be maintained constantly.”
The group entered into a PEG in delignification wooden frame to prevent polymer leakage during the phase transition. They also added to the acrylic material, to protect it from moisture. As before, the modified wood was transparent, but slightly cloudy, and durable and could accumulate heat.
Scientists note that the transparent wood has the potential to be more environmentally friendly than other building materials, such as plastic, concrete and glass. In addition to its ability to keep warm, transparent wood can be easily disposed of after it has accomplished its task. PEG and wood both decompose with time. The only part that is not biodegradable — it’s acrylic, but it can be replaced by another polymer bio-based.