Nano‐Porous Melt‐Blown Poly(Lactic Acid) Fiber Mat Air Filters for High Efficiency Particulate Capture

Abstract This study introduces a two‐step technique for developing nano‐porous, compostable melt‐blown nonwovens with high porosity, specifically engineered for high‐performance particulate capture in air filter applications. The first step entails creating a high melt flow index material by melt‐blending low‐viscosity polylactic acid (PLA) with a sacrificial additive, polyethylene glycol (PEG), of varying molecular weights. Rheological, compatibility, and thermal analyses are conducted on the sample blends. The MFI of the resulting blends ranges from 56 g/10 min (baseline PLA) to 238 g/10 min (PLA/PEG 400–10%), confirming their suitability for the melt‐blowing process. These blends are then formed into nonwoven mats using a twin‐screw extruder, producing microfibers with diameters between 1.05 and 2.64 µm. The second step involves boiling water etching to remove PEG, creating nanopores within the fibers. This etching process leaves a network of nanopores (50–200 nm in size), distributed throughout the microfiber structure. The PLA/PEG 2000 sample exhibits optimal properties, achieving ≈72% particulate capture efficiency for 0.3 µm NaCl particulates during air filtration testing. This study represents an innovative and eco‐friendly approach for creating nano‐porous nonwoven mats with potential applications in air filtration, water filtration, and battery separators, where high porosity is beneficial.