580 likes | 1.75k Views
Fiber spinning. SHEN, Qing E-mail: sqing@dhu.edu.cn. Melt spinning. Fiber thermal stable process. Wet spinning. Solution dry spinning. cited from Encyclopedia of Polymer Science and Technology. Vol. 6, p267, John Wiley & Sons, Inc. New York, 1993. Solution wet spinning.
E N D
Fiber spinning SHEN, Qing E-mail: sqing@dhu.edu.cn
Solution dry spinning • cited from Encyclopedia of Polymer Science and Technology. Vol. 6, p267, John Wiley & Sons, Inc. New York, 1993
Solution wet spinning • cited from Encyclopedia of Polymer Science and Technology. Vol. 6, p267, John Wiley & Sons, Inc. New York, 1993
Nanofibres – basic setup liquid jet ~ 105 Volt/m
Electro-spinning bending instability of electro-spun jet charges moving along spiralling path E ~ 105V/m Bending instability enormously increases path of the jet, allowing to solve problem: how to decrease jet diameter 1000 times or more without increasing distance to tenths of kilometres
Classical liquid jet 0.1mm Orifice – 0.1mm Primary jet diameter ~ 0.2mm Micro-jet diameter ~ 0.005mm • Gravitational, mechanical or • electrostatic pulling limited to • l/d ~ 1000 by capillary instability • To reach nano-range: • jet thinning ~10-3 • draw ratio ~106 !
Electrospinning observed at 30fps Average velocity of the fibres: 2 m/s 5 cm
Electron microscopy PEO nanofibres
In melt spinning a thin thread of molten polymer is extruded through a small capillary (spinneret). Solidification occurs at the freeze point as a result of cooling and the action of stresses on the thread along the spinline. The solidification process is referred to as flow induced crystallization.