Processing Nomex Nanofibers by Ionic Solution Blow-Spinning for Efficient High-Temperature Exhausts Treatment

Hard-to-dissolve polymers provide next-generation alternatives for high-performance filter materials owing to their intrinsically high chemical stability, superior mechanical performance, and excellent high-temperature resistance. However, the mass production of hard-to-dissolve nanofibers still remains a critical challenge. A simple, scalable, and low-cost ionic solution blow-spinning method has herein been provided for the large-scale preparation of hard-to-dissolve Nomex polymeric nanofibers with an average diameter of nearly 100 nm. After rapidly dissolving Nomex microfibers in the lithium chloride/dimethylacetamide (LiCl/DMAc) solution system, the conductive solution can be stably and conductivity-independently processed into nanofibers. The method optimizes electrospinning and avoids spinnability degradation and potential safety hazards caused by high electrical conductivity. Owing to nanofibrous structure and high dipole moment, Nomex nanofibrous filters show a stable high filtration efficiency of 99.92% for PM_0.3 with a low areal density of 4.6 g m^-2, as well as a low-pressure drop of 189.47 Pa. Moreover, the flame-retardant filter can work at 250 °C and 280 °C for a long and short time without shrinking or burning, respectively, exhibiting a high filtration efficiency of 99.50% for PM_0.3-10.0. The outstanding properties and low cost enable the efficient capture of PM from various high-temperature exhausts, making Nomex nanofibrous membrane an even more ideal industrial-grade air filter than polypropylene, polytetrafluoroethylene, polyimide, and ceramic nanofibrous filters.

Hard-to-dissolve nanofibers provide alternatives for high-efficiency and low-resistant air filtration but are limited by the universality and economics of fabrication methods. A scalable and efficient ionic solution blow-spinning strategy has herein been proposed in preparing hard-to-dissolve nanofibrous filters.

The online version contains supplementary material available at 10.1007/s42765-022-00231-x.