Study On Multiple Nozzles Electrospinning

Electrospinning is a straightforward and cost effective method for fabricating submicron fibers.Due to unique properties such as high surface area to volume ratio, small pore sizes,high porosity and so on,the ultrafine fiber membranes prepared by electrospinning process have been extensively studied and widely used for its potential applications in filter media,composite materials,biomedical applications, etc.The major technical barrier for manufacturing electrospun fabrics for applications is the production rate.Another major technical problem for mass production of electrospun fabrics is the assembly of nozzles during electrospinning. A straightforward multi-jet arrangement as in high-speed melt spinning cannot be used because adjacent electrical fields often interfere with one another,making the mass production scheme by this approach very impractical.In the present work,we designed a kind of large multi-jet nozzle,and several nozzles were used to improve the yield of electrospinning.The influence of applied voltage,tip to collector distance,distance between nozzles,number of nozzles,arrangement on electric field,jet path,production rate,critical voltage,membrane shape and fiber morphology were investigated.Taylor cone multi-nozzle electrospinning machine was also investigated in this paper based on electric field analysis.Ansoft Maxwell 3D software was used to analyze electric field of electrospinning.Research on electric field of single nozzle electrospinning was carried out.The results indicate that electric field near the nozzle is strong;near the collector is weak;near the edge on top of nozzle is strong;electric field of the middle on top of nozzle is weak.Electric intensity vector near the edge on top of nozzle is declining,and perpendicular to solution surface there.When tip to collector distance increases,the largest field strength on top of nozzle decreases. The relationship of jet path and electric int(?)nsity vector was investigated;results indicate:that influence of electric field on jet path is clear.Influence of tip to collector distance on jet was investigated;results indicate that jet number decreases along with the increase of tip to collector distance.Relationship of tip to collector distance with production rate and fiber web area was investigated;results indicate that production rate decreases along with the increase of tip to collector distance. Fiber web area increases along with the increase of tip to collector distance. Relationship of fiber web and tip to collector distance was investigated,results indicate that when the tip to collector distance is 200 mm,thickness of electrospun fiber web is uniform;solvent evaporation of fibers is sufficient.Relationship of fiber morphology and tip to collector distance was investigated;results indicate that average diameter decreases and standard deviation increases along with the increase of tip to collector distance.Relationship of fiber morphology and applied voltage was investigated;results indicate that average diameter and standard deviation of fibers decrease firstly then increase along with the increase of applied voltage. Considered with the production rate,fiber web quality and fiber quality,single nozzle electrospinning,applied voltage 25 kV,tip to collector distance 200 mm is suitable for spinning.The electric field of double nozzles electrospinning was analyzed,The results indicate that electric field strength on top of nozzle decreases because of electric field interference.When the distance between two nozzles is close,the decline of electric intensity vector is small.Influence of tip to collector distance on electric field was investigated;results indicate that the largest electric field strength decreases along with the increase of tip to collector distance.The largest electric field strength on top of double nozzles electrospinning is smaller than that of single nozzle electrospinning.Relationship of jet and electric field was investigated; results indicate that jets emit from all the edge on top of nozzle when the distance between two nozzles is 50 mm.Relationship of electric field with product rate and critical voltage was investigated;results indicate that product rate decreases along with the increase of tip to collector distance.Product rate increases along with the increase of distance between nozzles.Critical voltage increases along with the increase of tip to collector distance,and decreases along with the increase of distance between nozzles.Fiber web area increases along with the increase of tip to collector distance and distance between nozzles.Relationship of electric field and fiber web was investigated;results indicate that thickness of fiber web is uniform and solvent evaporation of fibers is sufficient when the tip to collector distance is 200 mm and distance between nozzles is 50 mm.Relationship of electric field and fiber was investigated;results indicate that average diameter and standard deviation of fibers decrease along with the increase of distance between nozzles.Considered with product rate,fiber web quality,fiber quality and nozzle density,double nozzles electrospinning,applied voltage 29 kV,tip to collector distance 200 mm,distance between two nozzles 50 mm is suitable for spinning.Influence of distance between nozzles,nozzle number and arrangement on electric field of multi-nozzle electrospinning was investigated;results indicate that electric field interference is smaller when the distance between nozzles is 50 mm. Electric field interference increases when the nozzle number increases.Electric field of three nozzles electrospinning with arrangement of linear,equilateral triangle and isosceles right triangle were contrasted;results indicate that difference of electric field near each nozzle with the arrangement of equilateral triangle is smaller. Influence of distance between two nozzles,nozzle number and arrangement on product rate,critical voltage was investigated;results indicate that product rate increases and critical voltage decreases along with the increase of distance between nozzles.When the nozzle number increases,Electric field interference increases, increment speed of product rate decreases,critical voltage increases.Diameter standard deviation of fibers spun with arrangement that makes electric field strength on top of each nozzle all larger is smaller,and product rate high,needed applied voltage smaller.Fibers spun from three-nozzle electrospinning were investigated, results indicate that standard deviation of fiber diameter is smaller when the arrangement that can makes difference of elect(?)ic field near each nozzle smaller. Considered with product rate,fiber web quality,fiber quality and nozzle density, nine nozzles electrospinning,equilateral triangle arrangement,applied voltage 46 kV,tip to collector distance 200 mm,distance between nozzles 70 mm is suitable for spinning.Taylor cone multi-nozzle electrospinning machine was developed based on electric field analysis.Transformer-like constant current high-voltage DC power supply was used.This kind of power supply is suitable for industrial production of multi-nozzle electrospinning.Bottom-up nozzle was designed to improve fiber web quality.Product rate was improved with the use of multiple nozzles.Interference of electric field was decreased with the use of PMMA cover.Reciprocate of nozzle box perpendicular to winding of substrate improved uniformity of fiber web. Beeline to-and-fro pump supplied solution to nozzles continuously.The design of collector avoided the damage of nanofiber web.Spun fiber diameter of six nozzles electrospinning with the arrangement Of equilateral triangle is thinner than that of single needle electrospining.Product rate of three nozzles electrospinning with linear arrangement increases clearly when tip to collector distance of middle nozzle is smaller.