New plastic clothing material could keep people cool

A team of researchers at Stanford University may now have a strategy for keeping us cool with that one layer.

The polyethylene-based fabric, described in an article in the journal Science, allows the human body to discharge heat so efficiently that a person wearing clothes made of this material would feel almost 4 degrees Fahrenheit (2.2°C) cooler than if they were wearing cotton clothes.

The engineers from Stanford University created a plastic clothing material that is woven into clothing that could cool your body. But it is also equipped with a unique mechanism that lets the infrared radiation emitted by the body.

Researchers started with an industrial-grade polyethylene that offered both light opacity and thermal transparency. Still, it enabled air, water vapor and thermal radiation to escape.

In a Science perspective, Massachusetts Institute of Technology scientist Svetlana Boriskina noted that a 1 to 4 C shift in a thermostat could save up to 45 percent of the energy required to cool a building. Cui is an associate professor of materials science and engineering and of photon science. The first one is not innovative, and is something that already exists in some fabrics: it lets perspiration evaporate through the material.

Thereafter, researchers modified the chemical properties of the material so that the second problem that polyethylene doesn’t allow water to pass through was fixed.

Much of our body heat is lost in the form of infrared radiation, an invisible and benign wavelength of light. A blanket helps to keep the body warm by trapping infrared heat emissions close to the body. It is these thermal radiation that make us visible in the dark with night vision goggles.

He said “very few studies, if any, had been conducted previously to design a textile favoring the dissipation of infrared radiation”.

Scientists has blended nanotechnology, photonics and chemistry to develop the material, which cools the wearer in two ways. The trouble is it also allows visible light to escape, Cui said.

The new material is based on the same clear, clingy plastic substance you probably use every day to wrap leftovers: polyethylene.

High-resolution SEM images of the new material. However, kitchen plastic can not be used for clothing as it is see-through and impervious to water. Nobody, except the most daring among us, would consider wearing completely see-through clothing.

So the engineering team worked at changing the pore size of the material and added other chemicals, allowing the heat and moisture out, but not visible light. Even the synthetic fibers used in cutting-edge wicking technology that kicks into gear when we sweat, cooling us by drawing that water away from our skin, still trap the infrared radiation. This resulted in a single-sheet material that meets the three basic criteria for a cooling fabric. To give it more structure, they then made a three-ply version, wedging a thin cotton mesh between two sheets of polyethylene.

They now needed to test the cooling potential of their three-ply construct against a cotton fabric of comparable thickness. Wearing anything traps some heat and makes the skin warmer.

‘If dissipating thermal radiation were our only concern, then it would be best to wear nothing’.