Transparent wood can store and release heat (video)



ORLANDO, Florida, April 3, 2019 – Wood may seem more comfortable in log cabins than in modern architecture, but a type of specially treated wood could be the modern building material of the future. Today, scientists report a new type of transparent wood that not only transmits light, but also absorbs and releases heat, which could save on energy costs. The material can withstand heavy loads and is biodegradable, opening the door for eventual use in ecological homes and other buildings.

The researchers will present their findings today at the 2019 Spring Meeting and National Exposition of the American Chemical Society (ACS). ACS, the world's largest scientific society, celebrates the meeting here until Thursday. It has about 13,000 presentations on a wide range of scientific topics.

A new video about the research is available at http: // bit.ly /HLS_Transparent_Wood.

"In 2016, we demonstrated that transparent wood has excellent thermal insulation properties compared to glbad, combined with high optical transmission," says Céline Montanari, Ph.D. Student who is presenting research at the meeting. "In this work, we try to further reduce the building's energy consumption by incorporating a material that can absorb, store and release heat."

As economic development progresses globally, energy consumption has skyrocketed. Much of this energy is used to light, heat and cool homes, offices and other buildings. Glbad windows can transmit light, which helps to light and heat homes, but does not store energy to use when the sun sets.

Three years ago, the principal investigator Lars Berglund, Ph.D., and his colleagues from the KTH Royal Institute of Technology in Stockholm, Sweden, reported optically transparent wood in the ACS journal Biomacromolecules. The researchers made the material by removing an absorbent component of the light called lignin from the cell walls of the balsa wood. To reduce light scattering, they incorporated acrylic on porous wood scaffolding. The team could see through the material, but it was vague enough to provide privacy if it was used as an important building material. The transparent wood also had favorable mechanical properties, which allows it to withstand heavy loads.

Based on this work, Montanari and Berglund added a polymer called polyethylene glycol (PEG) to the designated wood. "We chose PEG because of its ability to store heat, but also because of its high affinity for wood," says Montanari. "In Stockholm, there is a very old ship called You'll, and the scientists used PEG to stabilize the wood. So we knew that PEG can really penetrate wood cells. "

Known as a "phase change material", PEG is a solid that melts at a temperature of 80 F, storing energy in the process. The melting temperature can be adjusted using different types of PEG. "During a sunny day, the material will absorb the heat before it reaches the interior space, and the interior will be colder than the outside," explains Montanari. "And at night, the opposite happens: the PEG becomes solid and releases heat inside so that it can maintain a constant temperature in the house."

The equipment encapsulated PEG within the scaffold of wood design, which prevented the leakage of the polymer during the phase transitions. They also incorporated acrylic on the material to protect it from moisture. As in its previous version, the modified wood was transparent, although slightly cloudy and strong, but it had the additional advantage of storing heat.

The researchers point out that transparent wood has the potential to be more respectful to the environment than other building materials such as plastic, concrete and glbad. In addition to its thermal storage capacity, transparent wood could be easier to discard after it has performed its function. "PEG and wood are biological and biodegradable," says Berglund. "The only part that is not biodegradable is acrylic, but it could be replaced by another bio-based polymer."

Now, the focus is on expanding the production process to be industrially feasible. The researchers estimate that transparent wood could be available for specific applications in interior design in just five years. They also try to increase the storage capacity of the material to make it even more energy efficient.

A press conference on this topic will take place on Wednesday, April 3 at 9 a.m. Eastern time at the Orange County Convention Center. Reporters can register at the press center, Room W231B, or watch live on YouTube http: // bit.ly /ACSLive_Orlando2019 ("ACSLive_Orlando2019" distinguishes between upper and lower case). To ask questions online, sign in with a Google account.

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The researchers acknowledge the support and funding of the Wallenberg Foundations and the European Research Council.

The American Chemical Society, the largest scientific society in the world, is a non-profit organization constituted by the United States Congress. ACS is a world leader that provides access to information and research related to chemistry through its multiple databases, peer-reviewed journals and scientific conferences. ACS does not conduct research, but publishes and publishes peer-reviewed scientific studies. Its main offices are in Washington, DC, and Columbus, Ohio.

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Title

Multifunctional transparent wood for thermal energy storage applications.

Summary

Recent research on transparent wood compounds highlighted its potential to be used in buildings with thermal insulation thanks to the combination of low thermal conductivity, unique optical characteristics and favorable mechanical properties. In this study, a multifunctional transparent wood composite was designed, which extends the applications of transparent wood to thermal energy storage systems in pbadive buildings. Organic phase change materials (PCM), such as polyethylene glycol (PEG), can store and release latent thermal energy during a reversible phase change process. PEG is an environmentally friendly and recyclable organic PCM, which has a high latent heat and undergoes solid-liquid phase transitions in a suitable temperature range. However, the use of solid-liquid PCM is limited due to leakage problems that occur during the fusion process, which decreases its long-term thermal reliability. In this work, wood scaffolding was used to encapsulate PEG to prevent leakage during phase transitions. A multifunctional transparent wood composite was designed with features that include optical transparency and latent heat energy storage. During the experimental procedure, the PEG was first stabilized in form in a polymethyl methacrylate (PMMA) matrix, and then encapsulated in a delignified wooden scaffold. A delignification of the wood was carried out to remove the light-absorbing components (lignin) and, finally, transparency was achieved after the PEG impregnation of stabilized form in the porous wood cells. The prepared multifunctional transparent wood combines excellent thermal properties with a high latent heat and adjustable optical properties with a high optical transmittance and unique haze. The multifunctional transparent wood composite can be used as a filler in glazing structures with reduced thermal energy consumption.


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