Influence of processing conditions on polymorphic behavior, crystallinity, and morphology of electrospun poly(VInylidene fluoride) nanofibers

Abstract

The polymorphism and crystallinity of poly(vinylidene fluoride) (PVDF) membranes, made from electrospinning of the PVDF in pure N,N-dimethylformamide (DMF) and DMF/acetone mixture solutions are studied. Influence of the processing and solution parameters such as flow rate, applied voltage, solvent system, and mixture ratio, on nanofiber morphology, total crystallinity, and crystal phase content of the nanofibers are investigated using scanning electron microscopy, wide-angle X-ray scattering, differential scanning calorimetric, and Fourier transform infrared spectroscopy. The results show that solutions of 20% w/w PVDF in two solvent systems of DMF and DMF/acetone (with volume ratios of 3/1 and 1/1) are electrospinnable; however, using DMF/acetone volume ratio of 1/3 led to blockage of the needle and spinning process was stopped. Very high fraction of b-phase (79%-85%) was obtained for investigated nanofiber, while degree of crystallinity increased to 59% which is quite high due to the strong influence of electrospinning on ordering the microstructure. Interestingly, ultrafine fibers with the diameter of 12 and 15 nm were obtained in this work. Uniform and bead free nanofiber was formed when a certain amount of acetone was added in to the electrospinning solution.

Enhanced ferroelectric properties of electrospun poly(vinylidene fluoride) nanofibers by adjusting processing parameters

“…1,2 In this process, an electrically charged jet is accelerated toward a grounded collector when the electrical forces overcome the surface tension of the polymer uid. [5][6][7][8] Among these structures, particular attention has been given to the b phase in which chains in all-trans planar zig-zag conformations are packed into an orthorhombic unit cell. These brils have gained special attention in manufacturing electronic and photonic devices where anisotropic properties are competent.…”

Friction‐induced electroactive β polymorph of poly(vinylidene fluoride)

“…According to Table , peak melting temperature ( T m ) of wear debris is slightly higher than that of unworn PVDF. Due to all‐trans planar zigzag conformation and denser packing, melting temperature of β polymorph is commonly higher than that of α polymorph . Hence, increasing F (β) leads to higher T m .…”

Crystalline forms of PVDF fiber filled with clay components along processing steps

“…The crystallinity rate (χ c ) of PVDF was determined from the endotherm area assuming a heat of fusion of 100% crystalline material equal to 104.6 J g −1 for the α‐phases and 103.4 J g −1 for the β‐phases in eq. . The weight of the additives was systematically deducted from the total weight of the samples in order to obtain the actual melting enthalpy of the single polymer.…”