Formation of Polypropylene Nanofibers from Poly(ethylene-co-vinyl alcohol)/Polypropylene/Poly(ethylene-co-vinyl alcohol) Three-Layer Sheets by Using Laser-Assisted Melt Electrospinning

We used our new nozzle-free melt-electrospinning (M-ESP) system to produce polypropylene (PP) nanofibers. The M-ESP system includes a line-like CO2 laser beam melting device. We fabricated core (PP)-clad [poly(ethylene-co-vinyl alcohol; EVOH] nanofibers from EVOH (melt flow rate [MFR]: 14 g/10 min)/PP (MFR: 12 g/10 min)/EVOH three-layer sheets using the M-ESP system. The core-clad structure was formed by a wrapping phenomenon that is the result of the difference in the MFR values of the EVOH and PP melts. By removing the EVOH, we obtained PP nanofibers with the avg. dia. of 0.21 µm from the core-clad nanofibers. The nanofiber dia. was decreased by decreasing the MFR of the PP melt and the thickness of the PP layer in the EVOH/PP/EVOH sheet.