Aramid nanofiber (ANF) aerogels have received attentions as high-temperature insulators due to their highly porous structure, low thermal conductivity and excellent thermal stability. However, the common ANF fabrication methods still face drawbacks of low efficiency, high energy consumption and environmental pollution. Here, we report a novel, simple and aqueous-based treatment method in which aramid fibrils were fabricated by steam explosion of poly (p-phenylene terephthalamide) (PPTA) pulp. The obtained aramid fibrils have fine branches with a size smaller than micrometers. They can be evenly dispersed in water and the dispersion was directional frozen and freeze–dried to aramid fibril aerogels. The aerogel demonstrates abundant inter-fiber entanglement, large specific surface area with a specific surface area of 134.32 m2/g and high thermal insulation performance with thermal conductivity of 0.03137 W/m·K. Besides, aramid fibril presents high thermal stability over 500 °C. Taking advantage of these features, aramid fibril aerogels are expected to find potential applications in the fields of thermal insulation.
