Effect and durability of electret charging on filtration performance of meltblown polylactid acid nonwovens

The meltblow process was utilized to produce nonwoven fabrics from polylactic acid (PLA) in order to evaluate the potential of this bio-based polyester as an alternative to conventional polyolefins. Therefore, it was opposed against polypropylene (PP) meltblown as benchmark material, which is commonly used as a filter layer, for example in particle-filtering face masks. PLA was found to be processable at more moderate thermal process conditions, while its fiber diameters showed higher sensitivity to process parameter variation. This allowed the controlled deposition of both fine-fiber meltblown webs, but also coarse – spunbond-like – meltblown fiber webs. These showed minor mechanical performance but sufficient haptics and equal air permeability to spunbond PLA. Electret treatment of fine fiber PLA meltblown (1.43 µm average diameter) resulted in a raise of particle filtration performance (in paraffin oil) from 70% to >97%, exceeding the performance of PP meltblown of same grammage and fiber diameter distribution. The effect was also traceable over storage time (90 days), with just a slight reduction of 5% over the first days. These findings highlight PLA’s potential as a high-performance, bio-based alternative for filtration applications. Furthermore, the results contribute to the understanding of bio-polymer processing by comparing the processability, fiber morphology, and resulting performance of PLA and PP under similar process conditions.