Theoretical And Experimental Study On Preparation Of Nanofibers By Bubble Atomization Jet Electrospinning

Because the length and diameter ratio of nanofibers have certain advantages,they have been widely used in many aspects.Electrospinning plays an important role in the production of many nanofibers.Under the action of electric field force,the droplet at the tip of the needle will change from spherical to conical,and then split into tiny polymer jets,which will solidify into fibers.The singularity of its jet leads to the very low yield of nanofibers,which hinders their development.In order to improve the production efficiency of nanofibers,the bubble atomization technology was introduced into electrospinning in this paper.(1)Based on the bubble atomization technology and electrospinning technology,a new device for preparing nanofibers was designed,the functions of each component of the device were analyzed,and the integrated equipment of bubble atomization jet electrospinning was processed.The feasibility of the device was verified.The average diameter of the nanofibers produced was 186 nm,which met the performance requirements of nanofibers in the market.Different kinds of nanofibers were prepared with the equipment,and the fiber diameters were all about 200 nm,which proved that the equipment has wide applicability.(2)The equipment was used to prepare polyacrylonitrile(PAN)nanofibers,and the process parameters of bubble atomization jet electrospinning were optimized.The results show that when the solution concentration is 12%,the gas-liquid mass ratio is 5%,the additional voltage is 30 k V,and the spinning distance is 60 cm,the average diameter of the nanofibers is 194 nm,and the unevenness is 38%.Compared with the traditional single-needle electrospinning method,the diameter of the nanofibers is smaller,and the yield is increased by 70 times.(3)The forming mechanism of nanofibers prepared by bubble atomization jet electrospinning was investigated,and the working process of bubble atomization jet electrospinning was divided into three stages: gas-liquid mixing stage,atomization stage,and fiber forming stage.Through the study of the mixing process of two-phase flow inside the nozzle,the flow patterns of gas-liquid two-phase flow at different concentrations were simulated,and the flow patterns of the two-phase flow were observed by visualization.It was found that the gas-liquid mixing was more uniform when the two-phase flow pattern was bubble flow,and the gas-liquid mass ratio was between 1%-8%,and the bubble flow could be presented.The distribution of the airflow field outside the nozzle was analyzed,and the atomization form was observed with a high-speed camera.In the process of atomization,the ratio of liquid viscosity to gas-liquid mass had the greatest influence on the effect of jet atomization,and the quality of atomization effect became worse with the increase of the concentration.With the increase of the gas-liquid ratio,the atomization effect becomes better.The atomization quality can be controlled by reasonably controlling the solution concentration and the gas-liquid mass ratio during the experiment.By using COMSOL Multiphysics software to simulate the distribution of the airflow field and the static electric field outside the nozzle,the motion pattern of the jet in the double field is analyzed,and the fiber forming mechanism of the nanofibers is obtained.Compared with the traditional needle electrospinning mechanism,the nanofibers prepared by the bubble atomization jet electrospinning device have obvious advantages.