Mechanical Property Enhancement of Polylactide Nanofibers through Optimization of Molecular Weight, Electrospinning Conditions, and Stereocomplexation

Aligned poly(L-lactide) (PLLA) electrospun nanofibers of different molecular weights (M-w = 100K, 300K, and 700K) were collected using a rotating disk at take-up velocities of 63, 630, and 1890 m/min. Structural development within the spun fibers was examined. Enhanced crystallinities were observed within the fibers spun at elevated take-up velocities, from the polymers with increased M-w. Mechanical properties were evaluated using the single nanofiber tensile test. Despite exhibiting remarkable crystalline and amorphous orientation, the fibers prepared from polymer of molecular weight, 700K, displayed a significant drop in tensile strength when a take-up velocity of 1890 m/min was used to stretch and align the fibers. The finding suggests that an optimum processing condition exists in the preparation of mechanically superior PLLA fiber electrospun from different molecular weight. This study has also collected aligned nanofibers electrospun from poly(L-lactide) (PLLA)/poly(D-lactide) (PDLA) blended solutions at take-up velocity of 630 m/min. Highest stereocomplexation activity was observed within the fibers spun from PLLA/PDLA blend solution with weight concentration 50/50 wt/wt. The tensile results highlighted that, among the various blend ratios spun with take-up velocity of 630 m/min, the highest tensile strength was observed for the fibers obtained at a blend ratio of 50/50 wt/wt.