Melt-blowing of polymers for porous and functional air filters

Abstract

This thesis develops innovative, high-performance, melt-blown nonwoven materials for air filtration. The first chapter presents a two-step process to create nano-porous, compostable PLA nonwovens with high porosity for particulate capture. First, PLA is melt-blended with polyethylene glycol (PEG) of varying molecular weights to enhance melt flow index (MFI), producing blends with MFI values ranging from 56 g/10 min to 238 g/10 min. These blends are processed into microfibers, with diameters from 1.05 to 2.64 µm, using a twin-screw extruder. The second step involves boiling water etching to remove PEG and form nanopores (50–200 nm), achieving approximately 85% particulate capture efficiency for 0.3 µm NaCl particles. This eco-friendly method shows potential for air and water filtration and battery separators. The second chapter addresses the limitations of conventional face masks, which lack antibacterial or antiviral properties. To improve mask functionality, advanced melt-blown filters are created using polypropylene (PP) and Rose bengal (RB), a photosensitizer. The study investigates the impact of processing temperature on fiber morphology, filtration efficiency, and antibacterial properties. The optimized filters show superior antibacterial performance, particulate filtration efficiency, and breathability, offering significant improvements for personal protective equipment (PPE), with enhanced antimicrobial protection and durability.