Making a fabric largely invisible to body heat
Because its energy is lower than that of visible light, heat is known as infrared radiation. When radiation (such as heat or light) reaches an object, it can bounce off or travel around it.
When designing their new fabric, Cui and his team started with a common plastic. It’s known as polyethylene.
But the new material’s great advantage is its structure. Unlike the version of the plastic used in bottles and many bags, the new version includes tiny fused bubbles, or nanopores. Those bubbles — each around a billionth of a meter in diameter — are interconnected and let fluids (like air) flow from one side to another. Overall, when seen up close, the material looks like a very thin, very tiny version of a kitchen sponge.
The team came up with a way to test how well heat (that infrared radiation) will pass through the new fabric. When wearing a cotton shirt, a man’s skin temperature would climb about 3.5° Celsius higher than if he wore no shirt at all. But in a shirt made from the team’s new fabric, his skin would feel only 0.8 °C warmer than if he went shirtless.
That’s a big temperature difference. Someone who feels cool doesn’t need to set the thermostat for the air conditioning too low. And that would save money. For every 1 °C warmer the air-conditioning’s thermostat is set, residents will use about 10 percent less household energy, studies have shown.