Polylactic Acid Meltblown Nonwovens with High Filterability and Low Charge Decay: A Commercially Viable Strategy for Liquid Electret Charging Solutions

Polylactic acid (PLA) meltblown nonwovens are highly desirable alternatives to existing polypropylene air filtration materials, owing to their durability throughout their operational lifespan and biodegradable nature upon disposal. However, the practical utilization of PLA meltblown nonwovens remains challenged by the dual objectives of enhancing filtration performance and maintaining long-term stable charge storage. Herein, we implemented a commercially viable solution process for liquid electret charging, aiming to enhance the filtration efficiency (>95%) and charge stability (>1 year) of PLA meltblown nonwovens. In this process, the space charge is transferred from the liquid electret to the surface of PLA meltblown nonwovens to be polarized, and then the stable charges inside PLA fibers are formed by aging process. The resulting liquid electret charging PLA meltblown nonwovens showed an enhanced salt filtration efficiency of 99.5% and an oil filtration efficiency of 96.1%. The charge density and thermally stimulated discharge (TSD) measurements indicate that PLA meltblown nonwovens exhibit stable and abundant charge-carrying capabilities. A plausible charge generation and storage mechanism has been proposed. Moreover, evaluating the durability of these nonwovens is crucial for broadening their applications and addressing environmental and energy challenges.