Polymeric Nanofibers Made By Electrospinning And Their Application

Nanometer science and technology is a high-tech which investigate the motion laws and properties of electron, atom and molecule in the nano-scale. It is the aim of nanotechnology that the functional machines and relative products are prepared by controlling the single atom. The definition of nanomaterial is that at least one of three dimension of the material is in nano-scale. The most works and products in nanomaterial is nanoparticles, a zero dimension nanomaterial. The research of one dimension material is less than that of zero dimension nanomaterial. The interests of researchers is more and more focus on one dimension material, nanofiber.Recently, there are many methods such as drawing, template synthesis, phase separation, self-assembly, electrospinning, etc. developed to prepare the nanofibers. The electrospinning is a direct method to continuously prepare the polymeric nanofibers and to be further developed for mass production of one-by-one nanofibers. In electrospinning, when the electrical force overcomes the surface tension of polymer solution or melt, the charged jet is ejected. The jet is drawn in a line for some distance, then bends, followed a looping and spiraling route. The jet is drawing several millions times or spitting several times and the jet become very thin. Finally, the solvent evaporates or the melt solidifies. The nanofibers reach the collector in non-woven fabric.This thesis advanced a novel ideal of electrospinning. The standardelectrospinning prototype setup was designed and produced. Based on the standard setup, a new type setup of electrospinning was developed, that is the gas-jet/ electrostatic spinning setup which spinneret was improved by adding a gas jet part. Several conventional polymeric nanofibers were made by gas-jet/electrostatic spinning. Taking the polysulfone as a model polymer, the process conditions were studied in the electrospinning. The result was that polymeric nanofibers were made by gas-jet/electrostatic spinning as the same as the standard electrospinning. At the same time, the production of the nanofibers was higher in gas-jet/electrostatic spinning than in standard electrospinning. The process parameters affected on the diameter of nanofibers.The prototype standard electrospinning setup was designed and manufactured in vertical form. It was composed of the system of high voltage electrical source, solution input and collector. The voltage supplied by the electrical source was 0-70.0 kV, the power of injection pump was 100 kg / cm2 and the material of collector was stainless steel plane or web.The standard electrospinning method was improved and the gas-jet/electrostatic spinning was put forward. A new spinneret combined a gas jet orifice was designed. This new spinneret was made of gas canal, solution canal, gas buffer and capillary.The gas-jet/electrostatic spinning was validated by spinning the nanofiber of several polymer such as PAN, PS, PVA, PSU. The result was the nanofibers of these polymers could be prepared.The nanofiber of the polysulfone (PSU) as the model polymer was made by the gas-jet/electrostatic spinning. The diameters of PSU were from 50nm to 500nm. The difference between the standard electrospinning and the gas-jet/electrostatic spinning was compared during the electrospinning process. The production of the gas-jet/electrostatic spinning was several times larger than that of the standard electrospinning in the same collecting period. The result was that the mass production of nanofibers might be become possible by using this method. The process parameters of electrospinning process affected on the diameters of nanofibers were also researched. The parameters included applied voltages, the concentrationsof polymer solution and the distances between the spinneret and the collector. In experiments, adding the voltages from 27.5 kV to 45.0 kV, the diameter of PSU nanofibers reduced from 250nm to 150nm. When the distance between t increased from 15cm to 19cm, the diameter of PSU nanofibers decreased from 300nm to 150nm. When t...