GuestJune 29, 2021 AATCC Newsletter

From Hot to Cold and Cold to Hot: Fabrics that Work with your Body Temperature

 By Dr. Nicola Davies


Clothing is traditionally categorized by seasons—thick insulating jackets for winter and absorbent cottons during the hot summer. However, recent advances in temperature-sensitive textiles may blur some of the traditional lines dividing consumer garments. Today, textile innovators have developed technologies that equip fabrics with cooling/warming properties or the capability to regulate heat exchange or respond to body temperatures.


“Temperature management has become a big topic in textiles,” says Hans Kohn, Chief Operating Officer of Schoeller Textile AG in Switzerland. And rightly so. Temperature-sensitive textiles provide huge opportunities for personalizing body thermal comfort and for realizing energy consumption efficiency in heating or cooling the human body.

Energy consumption is especially significant against a backdrop of unexpected and possibly extreme climate fluctuations. According to Jifei Ou, founder and CEO of OPT Industries Inc., “In extreme conditions, developing textiles that can better shield the body from low or high temperatures is crucial.”


Cooling and Warming Effects

Some fabrics are now built with the ability to respond to changes in body or ambient temperatures to give the effect of cooling or warming the body of the wearer.

One method of providing this cooling/warming effect is by using Phase Change Materials (PCM), which are capable of altering their aggregate state from solid to liquid or vice versa when there is movement across a specific temperature range. Water is a perfect example of a PCM, as it freezes solid when the ambient temperature drops to 0°C and returns to liquid form when the temperature rises and further evaporates into gas when the temperature reaches 100°C.

According to Kohn, “Schoeller PCM uses PCMs, particularly microencapsulated paraffins, to store and release thermal energy to balance temperature differences.” The paraffins are developed in such a way that they respond to a specific temperature range. If the ambient temperature rises, they store excess heat. If the temperature drops, they release any stored heat.

For Ou, warming effects can best be incorporated into textiles through biomimicry, which is the practice of mimicking what can be seen in nature and applying it to human design. According to Ou, when it comes to developing textiles for extreme temperature conditions, “I believe the answer can be found in biological systems. We are working on heat insulation material inspired by feathers. Our goal is to produce a lightweight insulation material at scale without having to pull them from birds.”

Birds feathers may hold the answer to heat insulation


Regulating Heat Exchange

Temperature-sensitive textiles can also provide body comfort by applying the principles at work in thermal radiation, specifically by either reflecting or absorbing infrared rays. For example, Schoeller Textile AG has developed a special combination of dyes applied to textiles to help reduce or manage heat absorption:

  • Coldblack, a selection of dark dyestuffs and auxiliaries that reflect infrared rays. Once applied, it produces a dark textile that does not absorb infrared rays and thus gives the effect of reducing heat absorption.
  • “Solar+, which can be considered as the opposite of Coldblack, is a textile finishing that enhances the absorption of infrared rays to keep the textile warmer in cold but sunny conditions,” says Kohn.

Notably, Coldblack and Solar+ do not require a specific application technology. They can be applied through common dyeing technologies at various stages of dyeing and to various textile types. This means these dye materials can be applied to final products already in garment form, possibly transforming old garments into ones with either added heat insulation or cooling properties.


Extreme Insulation

Aerogels, which are a dehydrated matrix of silicon dioxide made up of 96% air, have also seen revolutionary applications. Aerogels are characterized by low thermal conductivity and breathability. When wrapped around an object, an aerogel blanket can insulate its coolness or warmness efficiently.

Aerogel insulation properties were typically applied in aeronautics, construction, and other industrial purposes. However, recently, these properties have also been incorporated into the design of lightweight and flexible textiles. For instance, Aspen Aerogel Inc. developed its pyrogel insulation to serve as an underfoot barrier in insoles of boots used by extreme mountain climbers.

However, aerogel has a high cost compared to most textiles. “Current methods of fabricating aerogel also produce the material in flat bulk. On the other hand, textile materials are made from fiber to yarn and then to fabric,” adds Ou. Therefore, aerogel’s application may be limited to non-woven textiles and specific garments such has footwear, specialized jackets, blankets, and gloves.


Smart Textiles

Some smart fabrics can adjust to body heat and act to both warm up or cool down. “To better manage body heat, we need to first better understand human physiology,” says Ou, explaining that research suggests that heating specific parts of the body can already give the effect of warming up the entire body. According to Ou, research indicates that regulating the temperature of the wrist can create the perception of coolness while regulating the temperature of the feet can influence the perception of warmness.

Smart sensors are another area of great interest within the field of temperature-sensitive textiles. “Textile sensors, which close the feedback loop for active heating/cooling design, are mature for mass market deployment,” says Ou. He explains that sensors are ideally machine knitted or woven into the fabric and may even be 3-D printed and embedded into the textile.

A basic example of the use of sensors in temperature-based textile products is the heatable softshell, which is a jacket built with carbon fiber infrared heating technology for hiking. “The heatable softshell uses textiles that can be actively heated, and its temperature can be controlled with sensors that pair with an app,” says Kohn.

These smart textiles may only be the beginning. With increasing research and development in temperature management technologies, we can expect their application to lead to the creation of textiles with smarter functions that offer enhanced comfort, efficiency, and flexibility in all temperatures.



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