The combination of electrospinning and forcespinning: Effects on a viscoelastic jet and a single nanofiber

The combination of electrospinning and forcespinning (otherwise called electrostatic-centrifugal spinning) was first proposed in our laboratory. A viscoelastic jet has a stretching force in the axial (ax→) and tangential (ay→) directions under electrostatic and centrifugal forces. The jet radius (R₀) will be dramatically decreased, and the jet velocity (υ₀) will be substantially increased due to a particular stretching force. The radius of curvature, the jet length, and the Taylor cone of a viscoelastic jet will be completely different when the jet velocity (υ₀) increases. A strong stretching force and a fast extension speed will form after optimizing the radius of curvature (by Reynolds (Re) and Weber (We) numbers), jet length (by Peclet (Pe) and Epsilon (ε) numbers), and Taylor cone (by dimensionless stress (Π₁) and Ohnesorge (Oh) numbers). Through dimensionless number and group analysis, higher Re(PC=9.38×10^-2, PLA=1.52×10^-1 and PAN=1.53×10^-2) and We(PC=13.8, PLA=15 and PAN=13.3) number of all three systems can collect the bead-free and uniform nanofibers. Similarly, higher P{cyrillic}₁(PC=1.83×10^-5, PLA=2.86×10^-5 and PAN=5.13×10^-9) and Oh(PC=39.60, PLA=29.22 and PAN=238.94) numbers refer to viscosity and electrostatic force dominate the jet behavior and obtained the nanofiber with high modulus, hardness, crystallinity and good molecular orientation. Hence, the uniaxially aligned polycarbonate, polylactic acid and polyacrylonitrile nanofibers with superior physical properties (modulus≥2.77GPa, 3.3GPa and 1.46GPa, hardness≥0.32, 0.26 and 0.22 and crystallinity≥3%, 37% and 21%) can be successfully manufactured in this process.