Selam material in self-heating underwear, also known as far-infrared radiation acrylic fiber, is a kind of silk material which uses advanced spraying technology to twist far-infrared radiation ceramics into acrylic fiber. Underwear made of this material can reflect the heat generated by human body back through underwear, thus achieving the effect of keeping warm.

In fact, heating underwear is not a "high-tech". Because any material can generate heat through moisture absorption. The mechanism of fiber moisture absorption and heat generation is that when fiber absorbs water, hydrophilic groups in fiber molecules combine with water molecules, and the kinetic energy of water molecules decreases, and at the same time it is converted into heat energy and released.

Generally, the moisture absorption and heating performance is closely related to the moisture regain of fibers. Fiber has high moisture regain and poor moisture absorption and heating performance. For example, wool and modal fibers have good moisture absorption and heating effects, while ordinary acrylic fibers and polyester fibers have poor moisture absorption and heating effects.

Extended data:

The raw material of heating underwear is a special fiber material imported from Japan around 2000, which actively heats up by absorbing the moisture emitted by the human body. This fiber material was first used for mountaineers, and later extended to the general consumption field, mainly used for making underwear. The materials used in the heating underwear produced by domestic manufacturers are all imported from Japan.

Because this kind of fiber material is expensive, general heating underwear is made of a small amount of heating fiber mixed with other fibers. Yang Shibin, chairman of the China Knitting Industry Association, added that, therefore, it is impossible for real heating underwear to rise that high, and generally it can actively raise the temperature by 2℃ to 4℃.

Moisture absorption and heating

The mechanism of fiber moisture absorption and heat generation is that when fiber absorbs water, hydrophilic groups in fiber molecules combine with water molecules, and the kinetic energy of water molecules decreases, and at the same time it is converted into heat energy and released. Usually, the moisture absorption and heating performance has a great relationship with moisture regain. When the moisture regain is high, the moisture absorption and heating performance is good, and when the moisture regain is low, the moisture absorption and heating performance is poor. For example, wool and modal fiber have good moisture absorption and heating effect. Ordinary acrylic fiber and polyester fiber have poor moisture absorption and heating effect.

Solar thermal storage

By adding special substances into the fiber to absorb solar energy and convert it into heat energy, it emits far infrared rays with long wavelength, which warms the interior of clothes.

Phase change heat storage

Heat can be absorbed, stored and released in the form of latent heat by adding heat-sensitive phase change materials to fibers. In the process of temperature change, it can change from solid to liquid, thus achieving the effect of heat absorption and heating.

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