Investigating the cooling power of chalk
29/08/2024
Inspired by the crushed limestone-based plasters historically used to keep houses cool in sunny climates, chemistry graduate student Evan D. Patamia and undergraduate Megan K. Yee, part of the team lead by professor of chemistry Dr Trisha L. Andrew, developed a method to integrate calcium carbonate – the main component in limestone and chalk – and a bio- compatible barium sulfate into a polymer coating, via chemical vapor deposition (CVD), a process developed by Dr Andrew.
The team noted that deflecting the sun’s rays and expelling natural body heat, a process known as radiative cooling, is usually achieved using synthetic chemicals such as titanium dioxide or aluminium oxide, or polyvinylidene difluoride, which is said to involve PFAS substances.
The coating has been tested on cotton or synthetic fabrics. “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,” said Mr Patamia. “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.”
Dr Andrew is part of a startup company, Soliyarn, that is working on scaling the CVD process for bolts of fabric. She said that it could also contribute to setting up a pilot-scale production for the novel chalk-based coating.
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