Numerical Simulation Study Of Multi-needle Electrospinning

Eletrospinning is a straightforward and cost effective method for fabricating submicron fibers.The electric force used as drawing force is one of the most remarkable differences betweenelectrospinning and traditional dry/wet spinning. The electric-field distribution of spinneret hasvery important influence on the formation and trajectory of jets. Therefore it is very necessary toresearch the electric field in electrospinning. To meet high liquid throughput requirements, in therecent past multi-nozzle system have been tested in China. The computational software COMSOLMultiphysics was adopted to simulate the electric field of spinneret, which could show theelectric-field distribution simply and intuitively. By this way, the effect of electric intensity onformation of fibers is analyzed in depth, to provide the reference for industrial production ofelectrospinning nanofibers.At first, the electric field of traditional single needle electrospinning was simulated, byestablishing the geometric model,setting the material attributes of model, adding excitations.Consequently, the electric-field distribution was shown. By analyzing the equipot^tial lines andvector diagrams of electric intensity and image of electric intensity cloud, combined theelectrohydrodynamics, it was conclusion that the electric intensity was maximum at the tip ofdroplet with the maximum surface charge density, where electric force would overcome surfacetension more easily, to extracted a jet. COMSOL Multiphysics software was employed to simulateand analyze the magnitude and distribution of the electric field intensity during multi-needleelectrospinning process. Systematic analysis was conducted on which the factors such as thenumber, diameter, length, spacing of the spinning needles and applied voltage influence themagnitude and distribution of the field intensity of each needle, and the theoretical foundationfor”end effect”.The results indicated that the peak value of field intensity occurs at needle tip for singleneedle electrospinning, while the peak values will occur at the outsides of the tip of the needleslocated at the bilateral sides of the linear needle array, and the field intensity of the middle needlesdecreases due to the suppression actions from the side needles resulting in “end effect”. Inaddition，the peak intensity of the outside needles was found to decrease significantly with the increasing number, diameter and length of the needles, while increase in the applied voltage anddecrease in receiving distance would enhance the peak intensity of electric field notably.The major technical barrier for manufacturing electrospun fabrics for applications, however,is the low production rate. The morphology of fibers was discussed by adjusting conditions suchas the voltage, the capillary to screen distance, the distance of adjacent spinning needles. Thestructures were characterized means by field emission scanning electron microscopy(FESEM). Weuse digital display conductometer to measure conductivity of solutions and we analyze the fibersdiameter size and distribution by means of Image-Pro Plus software.