Flow Field Simulation and Experimental Study of Centrifugal Spinning

Centrifugal spinning has demonstrated to be one of the effective techniques for the preparation of micro-/nanofibers. It is utilizing centrifugal force to extrude polymer solution/melt out of the nozzle and form a serious of stretching jets. Then, the micro-/nanofibers were formed after the evaporation of the solvent or drop down of jet temperature during jets stretching process. In the process, the structure of spinneret and the flow field of gas outside of spinneret has a great influence on fiber formation and quality. Therefore, the motion mechanism of spinning fluid in spinnerets and nozzles with different structures is studied in this paper. Based on the experimental analysis of fiber spinnability, the motion equation and wave equation of polymer jet in space Cartesian coordinate system are derived, and the two-dimensional flow field of polymer solution is analyzed. Through the simulation of the motion mechanism of the solution in different nozzles and the gas flow field outside different spinnerets, the optimal structure of the spinnerets and nozzles is determined. In addition, the effects of solution properties, rotation speed and nozzle diameter on the fiber morphology are analyzed. Results showed that spinneret of nozzle-free expressed more uniform flow field and were suitable for the preparation of highly oriented micro-/nanofibers. The spinneret with nozzles presented a more turbulent flow field, while fibers with smaller diameters and more uniform distribution could be obtained. The structure of nozzle had a greatly influence on fiber diameters, distribution of fiber diameters, and fiber morphology.