Recently, a paper published by China scientists in《Science》magazine shows that inspired by polar bear fur, scientists have invented a fiber woven garment that imitates polar bear fur. Although it is only one-fifth as thick as a down jacket, it is as warm as a down jacket.
In the process of seeking solutions, the team started with polar bear fur to solve the weaknesses and processing challenges of traditional aerogels. This breakthrough in aerogel technology, especially for textiles, has solved the shortcomings of traditional aerogels. Even after stretching, washing and dyeing, it can still maintain its endothermic characteristics.
This achievement was completed by Professor Bai Hao from the School of Chemical Engineering and Biological Engineering of Zhejiang University and Associate Professor Gao Weiwei from the Department of Polymer Science and Engineering. Among them, Gao Weiwei pointed out that this proof-of-concept fiber may one day be used to meet the needs of lightweight and durable clothing, such as sportswear, military uniforms and space suits, without using animal fur or down.
Porous Core Technology Of Imitating Polar Bear Fur
The research shows that aerogel is one of the best thermal insulation materials at present, and it has been used as thermal insulation material for buildings. However, the fibers made of aerogels are often too brittle to be woven into wearable textiles, and it is easy to lose heat insulation after washing and in humid environment. Therefore, researchers look for inspiration from polar bear fur. Each strand of polar bear fur has dozens of tiny pores, which can prevent heat from being conducted out and keep polar bears warm in the harsh Arctic environment. This porous core is surrounded by a dense, waterproof, flexible and tough shell.
Gao Weiwei and her colleagues used a method called freeze spinning to make a string of aerogel fibers, imitating the porous internal structure of polar bear fur. They used this method to make fibers from the solution extracted from silkworm chrysalis before. In order to replicate the shell of aerogels, researchers coated aerogels with an elastic material called thermoplastic polyurethane, which is often used in sportswear and equipment.
The stretched length of aerogel should not exceed 2% of its existing length, otherwise it will be damaged. However, this composite fiber inspired by polar bears can bounce back to its original length after being stretched by 1000% strain, which shows that it is stronger and more elastic than the previous aerogel fiber because of the elastic coating. The insulation performance of this fiber can still be maintained for 10000 times after being stretched to twice its length, and its structure or shape will not change when it is soaked in water, dried or dyed.
Next, the researchers knitted a sweater with aerogel fibers and compared its thermal insulation performance with that of down jackets, sweaters and long-sleeved cotton tops. The research team recruited a volunteer to put on each piece of clothing in a room where the temperature dropped to minus 20 degrees Celsius, and measured the surface temperature of the four pieces of clothing to evaluate their thermal insulation performance.
Good Thermal Insulation And Durability
Although the thickness of the imitation polar bear sweater is only one-fifth of that of the down jacket, it has the best thermal insulation effect among all garments. Its average surface temperature is 3.5 °C, while the average surface temperature of down jacket is 3.8 °C, which shows that the heat released by down jacket is slightly higher than that of sweater. The thermal insulation performance of cotton shirts and sweaters is the worst, with average surface temperatures of 10.8℃ and 7.2℃ respectively. However, the thermal insulation of aerogel sweater has not decreased after several turns in the washing machine, which shows that it is durable enough.
Yu Shuhong, a material scientist at Hefei University of Science and Technology of China, pointed out that although this research represents the further development of creating new thin and warm textiles, there is still a long way to go before the synthetic imitation polar bear fur clothing appears in ordinary clothing stores. At present, the method of manufacturing this kind of fiber is too slow and requires a lot of energy, so it is impossible to produce it on a large scale.
However, Bai Hao, the co-author of the research report, said that this is exactly what the research team is working on, and the research team is planning to improve its scalability.