A Systematic Single-Parameter Study for the Melt Electrospinning of Poly(lactic acid)

Melt electrospinning (MES) is a fiber manufacturing technique in which a molten polymer is stretched into ultrafine fibers by an electric field. MES combines the ability to produce very fine fibers with the advantages of solvent-free manufacturing. Its controlled variant, melt electrowriting (MEW), is especially valuable because it allows exceptional architectural precision, making it highly attractive for biomedical applications. This study presents a systematic, single-parameter evaluation of how nozzle-to-collector distance (nozzle height), applied pressure, and collector speed influence the morphological and thermal properties of the resultant poly(lactic acid) (PLA) fibers. Fiber diameter, uniformity, thermal transitions, crystallinity, and thermal stability are analyzed, the former being tuned over a wide controlled range (≈4-42 μm). Larger nozzle heights and higher collector speeds promote fiber drawing, yielding thinner (down to ~4 µm) and more uniform fibers, while increasing pressure results in progressively thicker fibers due to higher melt flow rates (up to ~42 µm). Thinner fibers exhibit higher glass transition temperatures, suggesting enhanced molecular orientation, whereas all fibers remain amorphous due to the rapid quenching applied during processing. Thermal stability improves at intermediate nozzle heights, correlating with the increased morphological uniformity. These results provide a clear, quantitative understanding of the physical mechanisms governing MES processing of PLA, delivering practical guidelines and processing-structure-property relationships for the design of tailored biodegradable scaffolds.