气流场和聚合物射流运动对液喷纺纤维形貌的影响
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摘要
为研究液喷纺丝过程中气流场分布和聚合物溶液射流运动对纤维形貌的影响,通过数值模拟分析变压力条件下液喷环形喷嘴下方的气流场分布,采用高速摄影技术捕捉聚丙烯腈(PAN)溶液射流在湍流场中的运动并分析其运动规律。结果表明:随气流压力的增加,气流中心线速度和湍流强度增加;液喷纺PAN微纳米纤维直径逐渐降低并变得均匀,但压力过大会恶化纤维形貌,并伴随着纤维束的出现。液喷纺丝过程中纤维的细化与气流的拉伸作用、聚合物射流的弯曲不稳定性和摆动作用等因素有关。
To investigate the influence of airflow field distribution and polymer solution jet motion on the morphology solution-blown fiber,the airflow field distribution below a solution-blowing annular nozzle was numerically simulated using the computational fluid dynamic approach,polyacrylonitrile( PAN) solution motion in the turbulent field was captured with a high-speed camera and the motion law was analyzed.The results show that with the increase of the airflow pressure,the airflow centerline velocity and turbulent intensity increases with the increase of air pressure,the diameters of solution-blown PAN fibers decrease and become more uniform. However,the fiber morphology become worse,with the emergence of some fiber strands under overhigh air pressure. The fiber thinning is correlated with factors such as stretching effects of airflow,bending instability and flapping motion of polymer solution jet,and the like.
To investigate the influence of airflow field distribution and polymer solution jet motion on the morphology solution-blown fiber,the airflow field distribution below a solution-blowing annular nozzle was numerically simulated using the computational fluid dynamic approach,polyacrylonitrile( PAN) solution motion in the turbulent field was captured with a high-speed camera and the motion law was analyzed.The results show that with the increase of the airflow pressure,the airflow centerline velocity and turbulent intensity increases with the increase of air pressure,the diameters of solution-blown PAN fibers decrease and become more uniform. However,the fiber morphology become worse,with the emergence of some fiber strands under overhigh air pressure. The fiber thinning is correlated with factors such as stretching effects of airflow,bending instability and flapping motion of polymer solution jet,and the like.
引文
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[2]MEDEIROS E S,GLENN G M,KLAMCZYNSKI A P,et al.Solution blow spinning:a new method to produce micro-and nanofibers from polymer solutions[J].Journal of Applied Polymer Science,2009,113(4):2322-2330.
[3]ZHANG L,KOPPERSTAD P,WEST M,et al.Generation of polymer ultrafine fibers through solution(air-)blowing[J].Journal of Applied Polymer Science,2009,114(6):3479-3486.
[4]SINHA-RAY S,YARIN A L,POURDEYHIMI B.The production of 100/400 nm inner/outer diameter carbon tubes by solution blowing and carbonization of core-shell nanofibers[J].Carbon,2010,48(12):3575-3578.
[5]ZHUANG X,YANG X,SHI L,et al.Solution blowing of submicron-scale cellulose fibers[J].Carbohydrate Polymers,2012,90(2):982-987.
[6]LOU H,LI W,LI C,et al.Systematic investigation on parameters of solution blown micro/nanofibers using response surface methodology based on Box-Behnken design[J].Journal of Applied Polymer Science,2013,130(2):1383-1391.
[7]CHEN S,HOU H,HARNISCH F,et al.Electrospun and solution blown three-dimensional carbon fiber nonwovens for application as electrodes in microbial fuel cells[J].Energy&Environmental Science,2011,4(4):1417-1421.
[8]SINHA-RAY S,KHANSARI S,YARIN A L,et al.Effect of chemical and physical cross-linking on tensile characteristics of solution-blown soy protein nanofiber mats[J].Industrial&Engineering Chemistry Research,2012,51(46):15109-15121.
[9]ZHUANG X,JIA K,CHENG B,et al.Solution blowing of continuous carbon nanofiber yarn and its electrochemical performance for supercapacitors[J].Chemical Engineering Journal,2014,237:308-311.
[10]MILLER D R,COMINGS E W.Force-momentum fields in a dual-jet flow[J].Journal of Fluid Mechanics,1960,7(2):237-256.
[11]NASR A,LAI J C S.Two parallel plane jets:mean flow and effects of acoustic excitation[J].Experiments in Fluids,1997,22(3):251-260.
[12]CHUNG T-S,ABDALLA S.Mathematical modeling of air-drag spinning for nonwoven fabrics[J].PolymerPlastics Technology and Engineering,1985,24(2-3):117-127.
[13]EROGLU H,CHIGIER N,FARAGO Z.Coaxial atomizer liquid intact lengths[J].Physics of Fluids A:Fluid Dynamics,1991,3(2):303-308.
[14]ENTOV V,YARIN A.The dynamics of thin liquid jets in air[J].Journal of Fluid Mechanics,1984,140:91-111.
[15]SINHA-RAY S,YARIN A L,Pourdeyhimi B.Meltblowing:I-basic physical mechanisms and threadline model[J].Journal of Applied Physics,DOI:10.1063//.3457893.
[16]YARIN A L,SINHA-RAY S,POURDEYHIMI B.Meltblowing:II-linear and nonlinear waves on viscoelastic polymer jets[J].Journal of Applied Physics,DOI:10.1063//.3457891.
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