Research On Optimization Design And Experiment Of Nozzle For High-speed Centrifugal Spinning

High-speed centrifugal spinning is a novel method to fabricate nanofiber by centrifugal force which is generated by high-speed rotating nozzles.Centrifugal spinning has aroused the concern of researchers because of its advantages such as higher production efficiency,wider range of spinning materials and lower energy consumption compared with traditional nanofiber fabrication technology.At present,further research is still needed for the optimization of centrifugal spinning equipment,especially the nozzle shape and nozzle structural parameters.The nozzle structures for high-speed centrifugal spinning are proposed in this paper.The optimization theoretical model of flow field in spinning nozzle is established and the structure parameters of spinning nozzle are optimized.First of all,the research background and research progress of nozzles are introduced in this article for high-speed centrifugal spinning.Several different structures of spinning nozzles are proposed based on the principle of centrifugal spinning.Secondly,the optimization theory of the flow field in the centrifugal spinning nozzle is studied by establishing the twodimensional flow field in the rectangular coordinate system.Thirdly,the movement of spinning solution is simulated in different centrifugal spinning nozzles and the structure parameters of different nozzles are optimized by orthogonal experimental design.Then high-speed centrifugal spinning experiments are carried out with different spinning nozzles and the effects of nozzle structures on nanofibers are analyzed by changing the experimental parameters.The main contents of the study are as follows:1.The traditional fabrication method of nanofiber and high-speed centrifugal spinning method are introduced.The research purpose and significance of high-speed centrifugal spinning nozzle are described.Both domestic and foreign research progress of electrospinning nozzle,melt-spinning nozzle and centrifugal spinning nozzle are introduced,which can provide some references for the optimization design of high-speed centrifugal spinning nozzle.2.The equipment composition and principle of high-speed centrifugal spinning are studied.Several different nozzle structures of centrifugal spinning are proposed,such as stepped nozzle,conical-straight nozzle,conical nozzle and curved-pipe nozzle.The relationships between the outlet velocity of the spinning solution and the structural parameters such as the nozzle length,the inlet diameter and the outlet diameter are analyzed by studying the movement of the solution in the spinning nozzle.3.The continuity equation and motion equation of spinning solution in the nozzle during the high-speed centrifugal spinning process are studied based on the knowledge of fluid mechanics.The two-dimensional flow field in the nozzle of centrifugal spinning is established in cartesian coordinate system.The solution flow in the centrifugal spinning nozzle is solved by finite element method,which provided theoretical support for the simulation and optimization of the centrifugal spinning nozzle.4.The solution motion in the nozzle of high-speed centrifugal spinning is simulated by Fluent.With the outlet velocity of spinning solution as the test index,the structural parameters of stepped nozzle,conical-straight nozzle,conical nozzle and curved-pipe nozzle are optimized by numerical simulation and orthogonal test.The influence degree of structure parameters on the outlet velocity of the solution is analyzed for centrifugal spinning and the optimal parameter combination of each spinning nozzle structure is obtained according to the results of orthogonal test.5.High-speed centrifugal spinning experiments are carried out respectively with stepped nozzle,conical-straight nozzle,conical nozzle and curved-pipe nozzle.The morphology,diameter distribution and production efficiency of the nanofiber fabricated by different centrifugal spinning nozzles are analyzed by changing the concentration of the spinning solution and the rotating speed of the motor.The experimental results show that the nanofiber fabricated by conical-straight nozzle and the curved-pipe nozzle has better morphological quality and smaller fiber diameter.The nanofiber generation efficiency of conical-straight nozzle and the curved-pipe nozzle is higher than stepped nozzle and conical nozzle.Finally,the research work of high-speed centrifugal spinning nozzle is summarized and analyzed in this paper.It is pointed out that there are some shortcomings in the research work,such as the establishment of the theoretical model for the flow field in the spinning nozzle and the experiment of high-speed centrifugal spinning nozzle.The follow-up improvement plan of the research work is also discussed.