Dynamics of melt-electrospinning and its application to the micro-fiber formation of biopolymers

溶融電界紡糸の動力学的解析とバイオマイクロファイバーの形成

2018-09-25

2018-09-25

The thesis consists of three chapters on the dynamics of melt-electrospinning and its application to the micro-fiber formation of biopolymers. The first chapter investigated the fabrication of core-sheath microfibers and the relationships among processing parameters, crystalline structures and the mechanical properties. The tensile strength and the modulus of the as-spun and the drawn fibers increased with increasing the take-up velocities. When the take-up velocity was above 500 m/min, jet became unstable and started to break up at the tip of Taylor-cone, decreasing the mechanical properties of the fibers. The drawing process facilitated the crystallization of PLLA and PHBH, and the tensile strength and the modulus increased linearly with increasing the draw ratio. The crystal information displayed from WAXD patterns and DSC heating curves supported the results of the tensile tests.The second chapter discussed the fabrication of ultrafine cellulose fibers with pure ionic liquid in high concentration. The maximum solubility of cellulose in 1-butyl-3-methylimidazolium chloride (BmimCl) can reach up to 20 wt% when the solution was stirred at 110 oC for 2 hours. The cellulose-BmimCl solution was then processed into homogeneous gels through the methods of recrystallization and casting. Pure cellulose fibers with perfect morphologies were achieved after melt-electrospinning and coagulation. The results of WAXD and FTIR indicated that the cellulose fibers were amorphous and chemically stable.The third chapter studied the electrodynamics and spinnability of melt electrospinning. A temperature-voltage phase diagram was constructed to distinguish the regimes of the bending, the whipping, and the break-up of the jet. Jet breaks up periodically at the tip of Taylor-cone if the polymer viscosity is too low or the elongation rate is not high enough to stretch the jet. The elongation rate for each segment of the jet keeps almost constant at a certain melt temperature, while the elongation rate increases and the solidification point of the jet shifts from the Taylor-cone to the target with increasing melt temperature. An analytic equation is proposed to estimate the jet diameter along the spinline before jet solidifies.

博士（工学）

京都工芸繊維大学

14303甲第905号

http://hdl.handle.net/10212/2502

eng

ETD

19

Thesis or Dissertation

Thesis