With climate change being at the centre of attention at the moment, many scientists are looking for ways to minimise the effects of hotter temperatures on our lives. One of the main working points is keeping cool, through technologies as sustainable as possible.
Cooling fabrics have been researched for years already. Ones that can block sunlight and release body heat are particularly sought-after. Textiles with light-refracting synthetic particles, including titanium dioxide or aluminium oxide, and ones with light-reflective properties using organic polymers in the weaving process have already been developed. However, due to their intensive fabrication process and the materials they use, large-scale production and commercialisation aren’t a sustainable way forward.
“If you walk out into the sunlight, you will get increasingly hot because your body and clothing are absorbing ultraviolet (UV) and near-infrared (near-IR) light from the sun”, explained Trisha L. Andrew, a chemist and materials scientist working on the project. “And as long as you’re alive, your body is generating heat, which can be thought of as light, too.”
Researchers from the University of Massachusetts Amherst have now found another way to develop a cooling fabric, using a mineral-polymer coating that can be applied to practically every kind of textile. The scientists were inspired by the crushed limestone-based plasters used historically to keep houses cool in extremely sunny places. The coating uses calcium carbonate and barium sulfate, two natural minerals which can be found in chalk. While the calcium carbonate particles reflect visible and near-infrared light, barium sulfate particles are capable of reflecting ultraviolet light.
During tests conducted on a day with temperatures over 90 degrees Fahrenheit (32 degrees Celsius), air temperatures underneath the treated fabric were registered to be around 8 degrees Fahrenheit (4.5 degrees Celsius) cooler than the ambient temperature in the middle of the afternoon. A difference of maximum 15 degrees Fahrenheit (over 8 degrees Celsius) was noted between treated and untreated fabric in the air underneath the sample.
“We see a true cooling effect. What is underneath the sample feels colder than standing in the shade”, said Evan D. Patamia, a graduate student at the University of Massachusetts Amherst who presented the results at the fall meeting of the American Chemical Society (ACS). “What makes our technique unique is that we can do this on nearly any commercially available fabric and turn it into something that can keep people cool. Without any power input, we’re able to reduce how hot a person feels, which could be a valuable resource where people are struggling to stay cool in extremely hot environments.”
If the technique is developed further and eventually commercialised, it could mean a true revolution in sun and heat protection for anyone, from employees having to work outside to children playing on the beach.
