Experimental Characterization And Mechanism Of Bubble-electrospinning

In the last decade, with the rise of nanotechnology, a great deal of attention has been paid to electrospinning method to produce continuous nanofibers, and theory research has also been explored systematically. Electrospinning is the simplest, the cheapest, and the most straightforward way to produce nanofibers by forcing a polymer solution or melt through a taylor cone with a high voltage electric field. The characteristic of nanofibers, such as high ratio of surface area to mass, unusual strength, high thermal and electric conductivity, and high surface energy make nonwoven nanofiber bulk fabric got via electrospinning process have diverse and wide range applications, anyway, the low production rate of traditional electrospinning limited it's application in large scale, bubble-electrospinning is a new method to fabricate nanofibers and has a potential of mass production.Polyacrylonitrile-based nanofibers prepared by electrospinning have attracted much attention in recent years for both fundamental research and industry, the bubble-electrospinning process of the PAN polymer solution is studied in this work, we evaluate the effects of the processing parameters such as solution concentration, applied voltage, distance of collection, relative humidity and environmental temperature on the diameter and the morphology of the bubble -electrospun fiber, We find that the diameter of the electrospun fibers increases with the increase of solution concentration; Applied voltage has an effect on the morphology of the bubble -electrospun fiber, and increasing electrospinning voltage can increase the diameter and plainness of the nanofibers as well; Increasing the distance of collection makes the diameter of the fibers decrease and the average of fiber assemble can decreases as small as 110nm,the thinnest fiber we got has a diameter of only 38nm; Environmental temperature seems has relatively little effect on diameter of the fibers, but as increasing of the temperature ,the uniformity of diameter distribution increasing notably ; The parameter of relative humidity has smaller effect when use PAN as polymer solution than PVP; In this work ,we also compare roughly the results got from bubble-electrospinning with traditional electrospinning process in the aspect of diameter and morphology of the nanofiber, thinner fiber and less sticking nanofiber assembly can got via bubble-electrospinning process with the same solution, scanning electron microscope (SEM) Photos showed the change of the morphology of the electrospun fibers via the different processing parameters and different fabricating method.The following sessions conducted a series of investigations to explore surface tension and how it relates to bubble formation. Properties of bubbles, bubble motion in electric field, numerical analysis of the process of collapsing and deforming both in the arise process of single bubble in the polymer solution and near the liquid boundaries is studied in the following part, in the process of bubble-electrospinning process, more than one jet can flow from a drop at the same time, therefore, production rate can increase sharply, its mathematical model and theoretical analysis worth further studying.