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.