New fabric regulates heat as needed

University of Maryland researchers have developed a synthetic yarn fabric that keeps warm or cools – it dynamically changes its properties depending on the situation.

The fabric looks inconspicuous, but it is able to change its properties. It can absorb or release heat as needed.Photo: Faye Levine, University of Maryland

The fabric looks inconspicuous but is capable of altering its properties. It can absorb or release heat as needed.

Photo: Faye Levine, University of Maryland

The range of high tech functional apparel is large. For athletes, it is now natural that their shirt, for example, moisture transported away from the body or stores heat on cool days. So far, they only had to decide which functional clothing to use for the upcoming training or competitive situation. This could change now. For scientists from the American University of Maryland (UMD) have developed a fabric that adapts its properties to the environment.

Intelligent textile is controlled by moisture

The intelligent textile is said to be the amount of heat passing through it flows through, automatically regulate. When it is hot and humid, like on a warm, sweaty body, the fabric lets heat (infrared radiation) through. As soon as it gets cooler and drier, because the athlete, for example, stops moving, the fabric reduces the escaping heat. So far, there were certainly substances that derived heat through different ways. However, it was not possible to eliminate this property when it was no longer needed and on the contrary residual heat should remain on the body.

The basis for the new yarn is two different synthetic fibers – one is capable To take in water, the other rejects it. This causes the material to warp when exposed to moisture. In fact, the yarn strands contract. The wetter they get, the tighter they are wrapped. This enlarges the spaces between the tissues. Basically, so the “pores” are opened in the fabric, which heat can escape. Although this effect is not very large, the individual fiber strands are also coated with carbon nanotubes, a conductive material, and the tissue deformation process affects the electromagnetic coupling between the carbon nanotubes in the coating.

Nanocarbon tubes function as well a Venetian

Carbon nanotubes are known to have high thermal conductivity. In this case, electromagnetic interactions occur in the range of the infrared wavelength, depending on how large the distance between the carbon nanotubes is. The closer they are together, the greater the coupling effect and the more infrared radiation is transmitted. The farther apart they are, the less infrared radiation is emitted. YuHuang Wang, professor of chemistry and biochemistry at UMD, explains it by example: “Although this is a greatly simplified picture, one can imagine the process as two antennas being brought together to regulate the type of electromagnetic waves they record. As the fibers are brought closer together, their radiation also changes. In the case of clothing, the result is that the substance reacts to the heat radiation of the body. “The researchers describe this process as a” gating “of the infrared radiation. Like a tunable blind, heat can be transmitted or blocked by this effect. Wang says the idea came to him when he looked at the blind in his office.

The reaction occurs almost as soon as the garment hits the moisture. Therefore, before the wearer realizes that he is hot, already use the cooling effect of his functional clothing. On the other hand, as soon as the body cools down and dries, the dynamic locking mechanism of the smart textile turns around. The remaining heat will then be stored.

Mass production of the tissue would be easily possible.

However, it will take a while for the tissue to enter the market, as the researchers previously provided further details of their development want to clarify. They emphasize, however, that the synthetic fibers used are readily available. The carbon coating can be easily added during the standard dyeing process, so that nothing stands in the way of subsequent mass production.

With this new development, once again the great potential of the nanocarbon tubes in the field of intelligent textiles. While on the one hand they can give substances great strength, for example for lifejackets, on the other hand they offer highly complex applications. At the University of Delaware, for example, textiles are being researched that can detect movements of a body through coatings made of nanocarbon tubes.

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