Investigation Of The Needleless Electrospinning Processes

Nanofibers are defined as fibers with diameters on the order of 100 nanometers. Nanofibers 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. Electrospinning is a straightforward and cost effective method for fabricating submicron fibers.However, one major technical barrier for manufacturing electrospun fabrics for applications is production rate. Up to now the overwhelming majority of studies adopted syringe electrospinning machine with extremely low output (0.1-1 g/h) and could not meet the requirements of commercial process. Recently, modified single-needle, multi-needle and needleless systems have been introduced to achieve multiple polymer jets and thus improve the output of nanofibers. Though the productivity is improved, some problems occur in single- and multi-needle electrospinning, such as needle clogging and disturbance of electric field. Needleless systems without these problems have attracted more attention, compared to modified single-needle and multi-needle setups. A novel needleless electrospinning setup, the " sputtering needleless electrospinning ", is developed in this paper. Further investigations of the eletrospinning process and Taylor cone theory of this new apparatus are also mentioned.Firstly, status quo of research at home and abroad in electrospinning process, apparatus and theory is summarized in chapter 1. In chapter 2, the orthogonal test method is adopted to explore; the further influences of solution concentration, processing parameters (applied voltage, gap distance) on the fineness and morphology of polyethylene glycol oxide (PEO) nanofibers.In chapter 3, based on traditional Taylor cone theory and A.L.Yarin's Taylor cone theory, the half angle of Taylor cone of PEO for electrospinning is studied using the sputtering needleless electrospinning apparatus. In addition, the influences of solution concentration, processing parameters (applied voltage, gap distance) on the half angle of Taylor cone are also investigated.In chapter 4, advantages and disadvantages of the sputtering needleless electrospinning apparatus are discussed. On the basis of that, a new needleless electrospinning apparatus is designed. The theoretical advantages of this new apparatus are mentioned. Furthermore, experiments of the new needleless electrospinning apparatus are carried out with polyethylene glycol oxide (PEO) as the raw material.In chapter 5, the conclusions of the whole article are summarized.