Stretched PTFE nanofiber nonwovens for superior air permeability and dust holding capacity in PM filtration

Abstract

In industrial environments, the massive emission of particulate matter (PM) and dusts, along with high temperatures, humidity, and exposure to toxic gases and chemicals, necessitate the development of industrial filtration media with high durability and enhanced dust holding capacity. To address these challenges, we propose a novel approach to extend the operational lifespan of high-performance filtration media by employing stretched polytetrafluoroethylene (sPTFE) nanofiber (NF) nonwovens. Utilizing an emulsification electrospinning process followed by an advanced stretching technique, sPTFE NFs were fabricated and tailored to optimize key microstructural properties, such as thickness, fiber diameter, and pore size. Notably, stretching the PTFE NF by 2- and 3-fold resulted in significant fiber thinning, effectively increasing internal pore size and substantially enhancing air permeability. The 3-fold stretched sPTFE (3-sPTFE) NF not only retained its nanofibrous air filtration properties but also improved its crystalline structural stability, achieving a high filtration efficiency (>92%) via a depth filtration mechanism, even with a reduced media thickness (28.96 μm), while exhibiting a lower pressure drop of 60.8 Pa. More importantly, the 3-sPTFE filter demonstrated an extended lifespan of 16,281 s and an a superior dust holding capacity of 107.7 g m−2, outperforming both less-stretched PTFE NFs and conventional expanded PTFE (ePTFE) membranes, which rely primarily on surface filtration. These results establish sPTFE NFs as a highly promising solution for industrial PM filtration, offering enhanced operational efficiency, prolonged usability, and reliable performance in harsh emission environments.