Stability analysis of bilayer polymer fiber spinning process

Gupta, Karan; Chokshi, Paresh

doi:10.1016/j.ces.2017.08.029

Cited by 5 publications

(1 citation statement)

References 29 publications

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“…Furthermore, elongational flow resistance supports the decrease in fluid retraction (Bergeron et al 2000; Bartolo et al 2007). Many studies also suggest that inkjet printing (Lampe et al 2005;Vadillo et al 2010;Hoath et al 2014;Jimenez et al 2018) and fiber spinning (Hyun 1999;Gupta and Chokshi 2017) are strongly affected by the elongational viscosity of the processed fluids.…”

Section: Introductionmentioning

confidence: 84%

Controlling the elongational flow behavior of complex shear-thinning fluids without affecting shear viscosity

Oswald

Willenbacher

2019

Rheol Acta

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Complex flow fields including high elongational deformation occur in numerous industrial processes such as spraying, coating, fiber spinning, and screen or inkjet printing. Fully exploiting the potential of these technologies suffers from a lack of knowledge regarding how elongational flow properties of the processed fluids affect the results of these operations. Here, we present two strategies that allow for varying the elongational flow behavior independent of shear rheology. First, two acrylic thickener solutions that differ with respect to the fraction of hydrophobic co-monomers and hence with respect to their degree of interand intramolecular hydrophobic association were mixed to vary the elongational relaxation time, as determined using capillary breakup elongational rheometry (CaBER), by almost two orders of magnitude without affecting shear viscosity of these solutions in a wide, processing-relevant shear rate range. Second, a substantial increase in the elongational flow resistance was achieved by adding a small amount of plate-like particles without affecting the shear viscosity of these thickener solutions. A fourfold increase of the elongational relaxation time was observed upon the addition of 3.5 vol.% of glass flakes to such a highly shear-thinning system. A similar effect was also observed for an industrial waterborne automotive basecoat due to added aluminum flakes. This work may be useful for product development since the control of extensional viscosity can improve technological applications, and the introduced model systems may therefore be used for systematic, goal-oriented investigations of the relevance of elongational flow properties in the technological processes mentioned above.

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Section: Introductionmentioning

confidence: 84%

Controlling the elongational flow behavior of complex shear-thinning fluids without affecting shear viscosity

Oswald

Willenbacher

2019

Rheol Acta

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Stability analysis of an electrospinning jet of polymeric fluids

Deshawar

Chokshi

2017

Polymer

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Stability analysis of non-isothermal fibre spinning of polymeric solutions

Gupta

Chokshi

2018

J. Fluid Mech.

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The stability of fibre spinning flow of a polymeric fluid is analysed in the presence of thermal effects. The spinline is modelled as a one-dimensional slender-body filament of the entangled polymer solution. The previous study (Gupta & Chokshi, J. Fluid Mech., vol. 776, 2015, pp. 268–289) analysed linear and nonlinear stability behaviour of an isothermal extensional flow in the air gap during the fibre spinning process. The present study extends the analysis to take in to account the non-isothermal spinning flow in which the spinline loses heat by convection to the surrounding air as well as by solvent evaporation. The nonlinear rheology of the polymer solution is described using the eXtended Pom-Pom (XPP) model. The non-isothermal effects influence the rheology of the fluid through viscosity, which is taken to be temperature and concentration dependent. The linear stability analysis is carried out to obtain the draw ratio for the onset of instability, known as the draw resonance, and a stability diagram is constructed in the $DR_{c}{-}De$ plane. $DR_{c}$ is the critical draw ratio, and $De$ is the flow Deborah number. The enhancement in viscosity driven by spinline cooling leads to postponement in the onset of draw resonance, indicating the stabilising role of non-isothermal effects. Weakly nonlinear stability analysis is also performed to reveal the role of nonlinearities in the finite amplitude manifold in the vicinity of the flow transition point. For low to moderate Deborah numbers, the bifurcation is supercritical, and the flow attains an oscillatory state with an equilibrium amplitude post-transition when $DR>DR_{c}$. The equilibrium amplitude of the resonating state is found to be smaller when non-isothermal effects are incorporated in comparison to the isothermal spinning flow. For very fast flows in the regime of high Deborah numbers, the finite amplitude manifold crosses over to a subcritical state. In this limit, the nonlinearities render the flow unstable even in the linearly stable regime of $DR<DR_{c}$.

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Stability analysis of bilayer polymer fiber spinning process

Cited by 5 publications

References 29 publications

Controlling the elongational flow behavior of complex shear-thinning fluids without affecting shear viscosity

Controlling the elongational flow behavior of complex shear-thinning fluids without affecting shear viscosity

Stability analysis of an electrospinning jet of polymeric fluids

Stability analysis of non-isothermal fibre spinning of polymeric solutions

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