Roofing membrane that stays cool for longer
A bilayer roofing material is designed to address two causes of performance loss – ageing and surface contamination.
The material combines a titanium dioxide-loaded thermoplastic polyolefin (TPO/TiO₂) substrate with a thin propylene-based elastomer/boron nitride (PBE/BN) surface layer.
The substrate scatters visible and near-infrared sunlight, while the upper layer reportedly improves UV reflection and mid-infrared thermal emission.
Published in Science Bulletin, the study from the Beijing University of Chemical Technology, China, reports that the two layers give the membrane 94.1% solar reflectance and 90.7% mid-infrared emissivity.
The PBE surface also has fewer high-adhesion regions than conventional TPO, making it harder for dust particles to stick. After 5,600 hours of accelerated ageing and contamination tests, the membrane is said to have still reflected around 83% of sunlight, retaining about 88% of its original performance.
In rooftop tests in Beijing, the material was found to have reduced surface temperature by an average of 9.4°C around midday compared with uncovered asphalt.
The membrane can be made using co-extrusion, which could allow it to be produced continuously over large areas, claim the scientists behind it.
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