Experimental study on relationship between jet instability and formation of beaded fibers during electrospinning

Abstract

Ultrafine fibers produced by electrospinning often exhibit bead-on-string structures, which have generally been considered to be undesirable "by-products" or defects. Theoretical analysis in the literature predicted three types of instabilities for an electrically driven jet: the axisymmetric Rayleigh instability, the electric field-induced axisymmetric, and whipping instability. The process of bead formation revealed that the formation of a beaded structure resulted from axisymmetric deformation and flow of the jet. Applied voltage, solution surface tension, and conductivity (or jet charge density carried by the moving jet) were theoretically demonstrated to be important for jet axisymmetric instabilities. Experimental results revealed that these parameters influenced the formation of beaded fibers in the same manner as they did for the axisymmetric instabilities. As a result, the axisymmetric instabilities were considered to be the most likely mechanism of beaded fibers formation during electrospinning. POLYM. ENG. SCI., 45:704 -709, 2005.

Preparation of carbon nanotube embedded in polyacrylonitrile (pan) nanofibre composites by electrospinning process

“…In general, surface tension tends to decrease the surface area per unit mass in fluids, and induces Rayleigh instability to the electrified jet [29][30][31]. A higher charge density and thus, higher solution conductivity causes a greater bending instability of the driven jet, resulting in a reduction of the fibre diameters [29,30,32].…”

Eletrofiação de Polímeros em Solução: parte I: fundamentação Teórica

“…As imagens correspondem a diferentes distâncias da ponta da agulha: a) 1 cm; b) 3 cm; c) 5 cm; d) 7 cm; e) 9 cm; f) 12 cm; g) 15 cm; and h) 30 cm. Reproduzido com permissão de Zuo et al [86] . tensão superficial, viscoelasticidade, massa molar, grau de emaranhamento das cadeias em solução e condições ambientais [79,82] .…”

“…tensão superficial, viscoelasticidade, massa molar, grau de emaranhamento das cadeias em solução e condições ambientais [79,82] . A Figura 7 ilustra o mecanismo de formação de contas proposto por Zuo et al [86] . Fong [53] descreve a formação das fibras com defeitos em forma de contas como sendo uma instabilidade capilar do jato devido ao desequilíbrio causado pelas flutuações na forma e densidade de cargas elétricas do jato.…”

Experimental and numerical study on isolated and non-isolated jet behavior through centrifuge spinning system

“…Too high flow rates resulted in thicker fibers, as they do not get enough time to dry before reaching the collector [55,56]. Using the spinning conditions indicated at Table 3, the dimensionless groups for quantitative simulation can be determined.…”