Investigation Of Electrospinning Processes And Methods

Nano-fibers obtained by electrospinning technique is characterized with large specific surface area and small aperture size thus rendering the technique a comprehensive prospects in areas like highly efficient filtering material, biomaterials, highly precise instrument, protective materials, nano composites etc. At present, though enormous amounts of studies are about electrospinning, most of them is mainly concerned with the spinnability of a polymer, while few attentions are focused on the influence of electrospinning process on fineness of fibers. Especially, up to now the overwhelming majority of studies adopted syringe electrospinning machine with extremely low output and could not meet the requirements of commercial process. Therefore the deep investigation into the electrospinning processes and high efficient electrospinning methods is necessary. This paper investigates the influence of single syringe electrospinning process on fineness of fiber from two aspects namely, experiment and theory. A sputtering electrospinning method is proposed and discussed. First, PVA nano-fiber felt are made using the single syringe electrospinning device, The influence of electrospinning processes i.e. the relation between collecting distance, the applied voltage in electrospinning and the viscosity of fluid on fineness of fiber is experimentally studied. In addition, the drawing process of polymer solution by an electric field is simulated using the bead-chain model. The diameter of the electro-spun fiber is obtained by computing the dynamic variation of the thickness of the polymer jet. And we make a comparison between simulated data and experimental data.Secondly, based on the analysis electrospinning apparatus available, a sputtering electrospinning apparatus is proposed. This equipment consists of the liquid-storage appliance, the uniform distributor, the glass rod, the metallic drum, the exhaust fan, the collecting drum, the waste solvent recovery unit and so on. Passing through the orifices at the tip of the uniform distributor, the spinning fluid is evenly distributed on the rotating metallic drum. In the high-voltage static field between the metallic drum and the collected drum, the drop on metallic drum is drawn to be fiber, and after the volatilization of solvent leaves filament.Thirdly, PVA spinning fluid is first trial-spun on the sputtering electrospinning apparatus. PVA fiber felt with diameter of 250 to 1000 nanometers can be made on the apparatus, with a productivity of 18 grams per minute, about 40 times of the syringe electrospinning machine. And, the influences of uniform distributor, metallic drum and its rotating speed on the spinning processes are analyzed. The suitable viscosity and electrostatic pressure on this machine is also determined. We further investigate the influence of the collecting distance, the applied voltage, the viscosity and the temperature of spinning fluid on the diameter of fiber.Finally, in order to prove the applicability of the sputtering electrospinning apparatus, 4.0% PEO spinning fluid is spun. Three hours' continuous spinning produces 48g PEO fiber felt. The influence of various spinning parameters on diameter of fiber are investigated experimentally, and a comparison is made with the single syringe electrospinning. In addition, we analyze the influence of voltage, electrical conductivity and viscosity of spinning solution on the formings of slub.