The concept of aerogel is very popular this year. Merchants claim that aerogel is an aerospace material that can achieve better warmth retention than down and is lighter and more breathable. So, can aerogel really replace down and become a new generation of "cold-proof magic weapon"?
     "Aerogel" is not a material
     Aerogel is a type of three-dimensional network structure material that envelops a large number of closed micropores. At present, there is no unified definition of it in the industry. Strictly speaking, it is not a material, but a material morphological structure. Many substances can be called aerogels as long as they can maintain their basic shape, have high porosity (generally above 80%) and low density. Aerogel contains a large number of nano-scale micropores and a high hollow rate, so the thermal conductivity is low and the insulation efficiency is good.

     The reporter investigated the aerogel products on the market, including aerogel cold-proof clothing, aerogel gold label P cotton clothing, aerogel aerocondensation double cold-proof clothing, aerogel cotton pants, aerogel thermal underwear, aerogel thermal quilts and other products. The reporter checked the washing labels of these products and found that a considerable part of them were made of ordinary fabrics and had nothing to do with aerogel. The fillers related to aerogel can be divided into three categories: one is 100% polyester fiber (polyester); the second is polyester fiber blended with viscose fiber (viscose fiber), polyacrylonitrile fiber (acrylic fiber), polyurethane elastic fiber (spandex), wool and other fabrics; the third is polyester fiber blended with polyimide fiber. Some merchants will specifically mark: "Polyester fiber uses aerogel wet-proof technology" or "Aerogel is detected to be polyester fiber." In other words, the aerogel material claimed by the merchant is actually polye                                                                                             

     Suitable for heat insulation in extreme environments
     Huang Chen, a professor at the School of Textiles of Donghua University, told reporters that the mechanical properties of aerogel fibers are generally weak, and the high porosity cannot support the spinning process of polyester fibers at all, and it is easy to break. Therefore, polyester fibers cannot be made into real aerogel structures. A considerable number of the above-mentioned merchants use aerogel coating technology, that is, a layer of silica aerogel is applied to the fabric of the clothes. However, the coating is generally very thin and the material is very brittle. It will fall off with wear and washing, and the warmth effect will become worse and worse. Some merchants will choose to use PU coating to stick aerogel powder to the fabric, but the adhesive will affect the porosity of the aerogel, which in turn affects the heat insulation effect of the clothes. Therefore, the warmth effect of aerogel clothing made with coating technology will gradually decrease with the increase in the number of uses.
     Moreover, space suits and protective clothing belong to a type of special personal equipment system, using polyimide aerogel as an interlayer to protect the human body from external high temperature environment damage. In the cosmic environment, the local temperature may reach 1000℃, at which time the down will be scorched, but the aerogel will not. In this case, aerogel has an advantage. Aerogel is more suitable for heat insulation in extreme environments, especially high temperature environments, rather than being made into cold-proof clothing for cold protection. It is not necessary to wear it daily. In addition, aerogel, as a thermal insulation material, is only part of the space suit system. In the cosmic environment, other materials and equipment are also needed to achieve the moisture and heat balance between the human body and the external environment. Space suits are a system completely different from daily clothing.
     The reporter experienced this aerogel cold-proof clothing that claims to be made of polyimide fiber. At around 0℃, the warmth retention is indeed good, but it will feel a little stuffy after wearing it for a long time. The reporter also saw some consumers comment that they still feel cold when wearing it at -20℃, and the warmth retention effect is not as good as down jackets. Since the main filling material of this cold-proof clothing is still polyester fiber, its characteristics are still similar to traditional chemical fiber cold-proof clothing.
     It can be seen that although there are many aerogel products on the market, many products are playing edge balls in terms of structure and performance, and there is a relatively serious phenomenon of hyping concepts. Consumers should pay attention to checking the fabric labels when purchasing and make rational choices according to their needs.