Study On The Core Shell Nanofiber Model Of Emulsion Electrospinning

Preparation of nanofiber materials by electrospinning is one of the most important academic and technical activities in the field of material science and technology in the world in recent decades.Compared with the traditional spinning method,electrospinning has the advantages of abundant raw materials,simple process and mild conditions.It has become one of the main ways to effectively prepare nanofiber materials.Emulsion electrospinning is one of the most important methods for preparing core-shell nanofibers.Compared with coaxial electrospinning,emulsion electrospinning has simple device,better controllability,wider application field,and has special significance in preparing fibers containing active substances,special drugs and other functional fibers.At present,the research on emulsion electrospinning mainly focuses on the experimental research on fiber forming in terms of emulsion materials and technological parameters,as well as the application of emulsion electrospinning.This paper with PVA as the water phase,TEO for oil phase is configured with four different water/oil ratio of spinning emulsion,respectively,9:1,7:1,5-1,electrostatic spinning experiments,respectively to change process parameters(including voltage,flow velocity,the diameter of the needle,accept distance),and the parameters of these effects of orthogonal experiment,by scanning electron microscopy(SEM)and transmission electron microscopy(TEM)for characterization analysis.Then,based on the basic knowledge of electricity and fluid mechanics involved in the process of electrostatic spinning,the specific stages of the process of electrostatic spinning were analyzed,including the stage of steady-state jet formation by Taylor cone and the stage of unsteady jet motion.Finite element analysis of electric field distribution in electrostatic spinning process was carried out through comsol-multiphysics software to analyze the influence of different voltage and distance parameters on electric field intensity.Finally,the forming process of Taylor cone in emulsion electrostatic spinning was simulated numerically,and the forming conditions and rules of Taylor cone under different voltages and emulsions were analyzed.The electric field simulation results show that the electric field intensity at the initial position of the spinning needle is the largest,and it increases with the increase of voltage and decreases with the increase of distance.Under the same voltage condition,the field strength at the pinhead will increase with the decrease of the distance,and the electric field force will also increase,which has a great influence on the formation of Taylor cone and jet flow.Through numerical simulation of the shape of Taylor cone forming,the results show that with the increase of voltage,the Taylor cone will shrink,which will affect the diameter of the fiber and the stability of the jet flow.When the voltage continues to increase,the Taylor cone will be destroyed,forming multiple jets and affecting the spinning process.When the surface tension of the emulsion increases,the Taylor cone begins to shrink,forming a good cone structure.As the surface tension continues to increase,the Taylor chase structure will also be destroyed.Finally,the optimized process parameters were obtained as follows:when PVA/TEO was 9:1,the loading voltage was 20kV,the needle diameter was 0.8mm,the spinning speed was 0.4ml/h,and the receiving distance was 13cm.Under such parameters,the fiber morphology was good,and the nanofiber with good coreshell structure was formed.This also verifies the reliability of the simulation of spinning process.