Electrospinning fabrication of partially crystalline bisphenol A polycarbonate nanofibers: Effects on conformation, crystallinity, and mechanical properties

The application of an electrostatic and centrifugal field (1800 rpm) in a novel electrospinning process was shown to improve the degree of uniaxial alignment in polymer nanofibers and to enhance orientational order in polymer chains, producing bisphenol A polycarbonate (BPAPC) nanofibers with superior mechanical properties. High-speed videography showed that the additional centrifugal field effectively removed electrical bending instability and promoted molecular orientation during the electrospinning process. Infrared spectroscopic (IR) characterization revealed that the fraction of trans–trans conformers in BPAPC nanofibers reached 67% under optimal electrospinning conditions (25 kV and 1800 rpm at 25 °C). Modulated differential scanning calorimetry (MDSC) and wide-angle X-ray diffraction (WXRD) assays showed that a degree of crystallinity of 6.5% could be achieved. Moreover, two crystal phases at angles of 2θ = 17.3° and 21.9° were produced in BPAPC nanofibers. The elastic modulus of BPAPC nanofibers with a crystallinity of 6.5% was 7.11 and 5.13 GPa, as measured via atomic force microscopy (AFM) and nanoindenter (NI) experiments, respectively. These results demonstrated that the mechanical behavior of BPAPC nanofibers could be improved by conducting the proposed electrospinning technique. Moreover, BPAPC nanofibers produced through the proposed method could be potentially applied for the reinforcement of composites.