Preparation and characterization of poly(lactic acid) meltblown nonwovens modified by electrets and co-plasticizers

The Compound modifications of poly(lactic acid)(PLA) were conducted by using nano SiO₂ or one organic matter as the electrets (O-electret), and using epoxy soybean oil (ESO) and poly(ethylene) (PEG) as the combined plasticizers, respectively. Then the biodegradable electret-plasticizer/PLA meltblown nonwoven composites were manufactured on a commercial meltblown production line. The melt flowability of modified PLA chips was tested by using a torque rheometer and a melt flow index (MFI) instrument. It is found that addition of ESO and PEG improves the MFI to 110 g/10 min. The mechanical properties of meltblown nonwoven composite were tested by DMA. The relevant results indicate that the strength and plasticity of meltblown nonwoven composites can be remarkably enhanced after being modified by plasticizers. Filter media testing platform was used to evaluate the filtration performance of electret-plasticizer/PLA meltblown nonwoven composites. It is found that introduction of electret could improve the PM2.5 filtration efficiency of that to 86% or more. SEM observations were eventually employed to study the micromorphology of the nonwoven composites, the result shows that the ratio of fine fibers within the PLA meltblown nonwoven has been increased notably after electret modification, and with the help of plasticizers such microscale fibers became relatively longer and finer, hence the interlacement of these fibers turned more complex.