American researchers at Stanford University have developed an inexpensive plastic-based textile that is more heat-resistant. This new textile could cool our bodies without the need for air conditioning, which is expensive for our wallets and the planet.
Dwriting their work in the magazine ScienceResearchers suggest that this new family of fabrics could become the basis for clothing for warm countries.
"If we can cool people rather than the buildings where they live and work, we could save energy."says Yi Cui, an assistant professor of materials science and engineering at Stanford University in California.
This new material, the result of the marriage of nanotechnology, optics and chemistry, allows the body to discharge heat. According to the scientists, the body can cool down two degrees Celsius more than if it were wearing a cotton garment.
Like cotton or linen, this new material, made from polyethylene, allows sweat to evaporate. But it is also equipped with a novel mechanism that lets infrared radiation emitted by the body pass through.
All objects, including our bodies, emit heat in this form of invisible light waves. Blankets keep us warm by trapping these heat emissions. It is this heat radiation that makes us visible in the dark with night vision goggles. « Between 40 and 60% of body heat is dissipated as infrared radiation when we sit at the desk."says Shanhui Fan, a professor of electrical engineering and one of the co-authors of the study. According to him, "Very few, if any, studies had been carried out to date to design a textile that would promote the dissipation of infrared radiation.
Researchers are using a variant of polyethylene commonly used in the manufacture of batteries. This material has a specific nanostructure that is opaque to visible light but permeable to infrared radiation. It is this characteristic that would allow the body's heat to dissipate. Stanford engineers then modified the industrial polyethylene by treating it in such a way that water vapour molecules could evaporate through nanopores in the plastic. This allows the material to breathe like a natural fibre.
To test the cooling ability of this experimental fabric compared to a cotton cloth of the same thickness, researchers placed a small piece of the fabric on a surface with the same temperature as the skin and measured the amount of heat retained by each sample.
According to Shanhui Fan, this study opens the way to new ways of cooling or heating objects without the use of external energy sources.
Researchers are now working on improving their product to offer a wide range of colours and textures. It is up to fashion designers to make it their own to offer us a refreshing wardrobe for the coming warm-up season.