Flexible aerogels are used in clothing, but a thin layer is warmer than down?

Aerogel is a solid material with a nanoporous network structure. It is also the world's lightest solid material. It is known as one of the top ten new materials for changing the world with graphene and fullerenes. It has outstanding performance in the fields of heat, optics, electricity, mechanics, acoustics, etc. It is a military-civilian dual-use technology with great application value.

The history of aerogels dates back to 1931, when the Pacific University of California first prepared silica aerogels by supercritical drying of ethanol. Although the thermal adiabatic properties of this silica aerogel are very good, the outstanding brittleness characteristics limit its wide application. Until the 1990s, NASA proposed to solve the problem of spacecraft storage and transfer of thermal insulation materials for liquid fuel tanks. Invented the idea of ​​developing flexible aerogel composites and signed a Small Business Innovation Research (SBIR) project contract with Aspen Systems of the United States in 1992 to develop flexible, durable and easy to use aerogels.

Silicon aerogel

In 1999, Aspen Systems developed a fiber-composite aerogel superinsulation material, and in 2001 established Aspen Aerogel to commercialize aerogel materials, opening the aerogel as a thermal insulation material. This fiber aerogel composite is rapidly applied to low-temperature fuel tanks and pipelines in the aerospace industry, and is extended to civil applications such as construction, electrical appliances, and refrigeration equipment.

Electrospinning composite aerogel film

Thanks to good thermal performance, OROS has partnered with Aspen Aerogels to launch its first Lukla jacket with this fiber aerogel composite as insulation. However, due to neglecting the problem that the aerogel insulation material may peel off during exercise, the garment may lose thermal insulation performance with use; the silicone aerogel must be packaged according to the strong hygroscopicity, resulting in the garment being almost airtight. .

Since then, the company has carried out a series of breathability and durability improvements based on the first garment, and developed a new polymer composite aerogel called SolarCore, which reduces the weight of the jacket by 40% and breathability. Better, it can be widely used in gloves, snow pants, hats, shirts and other products.

Aerogel Technologies of the United States has also developed the Aerotherm aerogel warming series for use in the field of clothing and footwear based on the aerogel of Aspen Aerogels. Aerotherm aerogel material is a porous material made by impregnating a silicon aerogel into a non-woven flexible substrate. Its thermal insulation performance is 2 to 8 times that of traditional thermal insulation materials, and it has excellent pressure bearing capacity. Thermal performance is virtually unaffected by pressure – maintaining its original thickness above 95% and warmth retention above 97% even at 15 psi.

Therefore, only 2mm of Aerotherm aerogel material can be used to increase the warmth of the garment by 2 to 3 times, especially in areas that are often stressed, such as knees, elbows, buttocks, soles, and the like. Garments made from this material can achieve better thermal insulation without the use of thermal interlayer materials, while mezzanine insulation structures often lose warmth due to compression.

In addition, polymer-based polyimide flexible aerogels developed by NASA have also begun to seek industrialization in the civilian sector. In 2015, FLEXcon obtained the technology license from NASA GRC and cooperated with Blueshift, which is also developing polyimide aerogel, to produce NASA high-grade aerogel materials on a larger scale. . In addition to pipe insulation products used in extreme environments, FLEXcon is also developing high-end outdoor products for polyimide aerogels, such as outdoor clothing, gloves, shoes, tents and so on.

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