Preparation and Characterization of Poly(lactic acid) Micro- and Nanofibers Fabricated by Centrifugal Spinning

In this paper, poly(lactic acid) (PLA) micro- and nanofibers were successfully prepared by centrifugal spinning which is a more simple and effective approach to produce micro/nanofibers. The morphology of fibers was investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), while their thermal properties by differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA). The results showed that the diameter of PLA fibers increased significantly with increasing solution concentration and decreased slightly with increasing collection distance. It can be controlled below 500 nm at the optimal process parameters which were found to be spinning solution concentration of 6 %, spinneret diameter of 0.11 mm, rotational speed of 5500 rpm and collecting distance of 15 cm. Although the crystallinity of the PLA fibers was weaker than that of the PLA pellets due to the insufficient adjustment of the molecular chain in rapid solvent evaporation and short stretching time, it can be improved by increasing the rotational speed from 4500 to 7000 rpm. The glass transition temperature (Tg) and melting temperature (Tm) of the fibers were nearly keeping constant compared to the PLA pellets. Its good degradability was demonstrated by the loss of fibers structure completely within 5 hours of immersion in NaOH at pH 13.