Solution blow spinning: parameters optimization and effects on the properties of nanofibers from poly(lactic acid)/dimethyl carbonate solutions

Solution blow spinning (SBS) is a process to produce non-woven fiber sheets with high porosity and an extremely large amount of surface area. In this study, a Box–Behnken experimental design (BBD) was used to optimize the processing parameters for the production of nanofibers from polymer solutions consisting of poly(lactic acid) (PLA) dissolved in dimethyl carbonate. In addition, a comparative study between SBS fibers and cast film was performed to verify the influence of the SBS process on the crystallinity and thermal properties of PLA. The PLA concentration in polymer solutions was the most significant parameter affecting fiber diameter. The BBD analysis revealed that small diameter fibers were best obtained by a combination of 8 % w/v PLA concentration, 80 psi air pressure, and a feed rate of 50 µL min⁻¹. The comparative study showed that both the SBS and the film casting processes increased the PLA crystallinity. However, the PLA films had a higher degree of crystallinity compared with the fibers made by the SBS process (39 and 17 %, respectively), which was attributed to the high shear created at the SBS nozzle inducing orientation and chain alignment. During the fiber formation, crystals formed with varied morphology including the α′-crystals, which have a less ordered structure and lower thermal stability compared to the α-crystals. The lower thermal stability of SBS fibers compared to the films can be explained by the lower degree of crystallinity and also by the higher surface area which can accelerate the weight loss process.