Electret characteristics of melt-blown polylactic acid fabrics for air filtration application

Polylactic acid (PLA) is a biodegradable and biocompatible polymer. Melt-blown PLA electret fabrics have become attractive materials for air filter applications. Its filtration performance mainly depends on the electrostatic effect originating from electrets. How to improve their electret behavior and then to enhance their filtration efficiency has always been challenging. In this article, three melt-blown PLA fabrics with different morphological or crystal structure are made from different process conditions or ingredient. The electrets are formed by means of corona charging technology. Their crystalline and morphological structure was analyzed, and filtration performance was measured. Their charge-trapping feature was studied by thermal stimulating discharge technology. The results proved that the air filtration efficiency of three melt-blown samples improved a lot when electrets were formed. Different crystalline structures of PLA fabrics will result in differences in their electret charge-trapping feature. The PLA fabrics with semi-crystalline characteristics display a regular charge-trapped level distribution and amorphous structure hints the diversity of charge-trapped levels. The deference in filtration resistance is mainly ascribed to the different fiber diameters and their distributions. More narrow distribution of fiber diameter leads to more compact fabrics and to higher filtration resistance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48309.