EFFECT OF GAS FLOW RATE ON CRYSTAL STRUCTURES OF ELECTROSPUN AND GAS-JET/ELECTROSPUN POLY(VINYLIDENE FLUORIDE) FIBERS

The effect of gas flow rate on crystal structures of electrospun and gas-jet/electrospun poly(vinylidene fluoride) (PVDF) fibers was investigated. PVDF fibers were prepared by electrospinning and gas-jet/electrospinning of its N,N-dimethylformamide (DMF) solutions. The morphology of the PVDF fibers was investigated by scanning electron microscopy (SEM). With an increase of the gas flow rate, the average diameters of PVDF fibers were decreased.The crystal structures and thermal properties of the PVDF fibers were investigated by attenuated Fourier transform infrared spectroscopy (AT-FTIR), wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). It was found that electrospinning and gas-jet/electrospinning of PVDF from its DMF solutions promoted the formation of β phase. Moreover, gas-jet/electrospun PVDF fibers exhibited higher crystallinity and β phase content than electrospun fibers did. Similar with electrostatic force, the drawing force of gas jet may induce the conformational change to all-trans (TTTT) planar zigzag conformation, and then promote the formation of the β phase.