Towards superior thermal insulation: Flexible Kevlar aerogel fibers with ultrafine size

Aramid aerogel fibers, characterized by their 3D porous structure, high specific area, etc., are emerging as thermal insulation materials with significant appeal for high-temperature applications. To obtain better thermal shielding and more compact aerogel fabrics, ultrafine, highly flexible and easily bendable aerogel fibers have been developed, called ultrafine Kevlar aerogel fibers (UKAF). These fibers are observed to be about 100 μm in diameter, finer than reported in most previous studies, and perform well in tensile and heat resistance. The breaking strength of the UKAFs can be as high as 6.5 MPa, thanks to the use of high-concentration spinning suspensions. Besides, these ultrafine fibers also inherit the excellent thermal stability of Kevlar, almost do not decompose before 480 °C. In addition, the resultant UKAFs can be easily twisted, knotted, and braided. The fabrics braided from such fibers are able to show a significant temperature drop gradient of 130 °C mm when exposed to a hot plate of 300 °C, indicating superb performance in thermal insulation. Given these, the flexible UKAFs prepared in this study that possess a distinctive set of properties will be highly advantageous across various applications, particularly in the field of thermal insulation.