An international team of researchers has developed an innovative solution to combat heat in buildings without resorting to traditional systems that consume energy and aggravate climate change. Porous plastic sheets, created from polymethyl methacrylate (PMMA), can reduce the interior temperature of closed spaces by up to 8.4 degrees Celsius through radiative cooling.
How PMMA Porous Plastic Sheets Work
Akhlesh Lakhtakia, a professor of engineering sciences and mechanics at Penn State University, led this project with Mingkai Lei of Dalian University of Technology in China. Unlike other materials that only reflect infrared light, these sheets reflect both visible and shortwave infrared light, providing more efficient cooling during the day.
The sheets, which are about one-twelfth of an inch thick, are made using a powder sintering process that creates internal pores. These pores scatter light at different angles, allowing heat to radiate out into space. At night, the sheets emit mid-wave infrared light, continuing passive cooling without the need for electricity.
The researchers tested the sheets in real-world and laboratory conditions. In a box exposed to sunlight, the interior temperature dropped from 80 to 65.3 degrees Fahrenheit, compared with a cardboard box that only dropped to 75.2 degrees.
Lakhtakia points out that although PMMA sheets degrade after several years of solar exposure, they can be recycled and reused. This technology not only reduces dependence on air conditioning systems, but also opens up opportunities for job creation related to their installation and maintenance.
The project was funded by the National Natural Science Foundation of China and the Fundamental Research Funds for the Central Universities. In addition to Lakhtakia and Lei, researchers from Dalian University of Technology participated, including Yupeng Li, Hui Zhao, Xiangren Meng, Yishu Zhao and Haodong Liu.
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Source and photos: Penn State University
