Direct measurement of rheologically induced molecular orientation in gas separation hollow fibre membranes and effects on selectivity

Ismail, Ahmad Fauzi; Shilton, Simon; Dunkin, Ian R.; Gallivan, Sean L.

doi:10.1016/s0376-7388(96)00274-8

Cited by 73 publications

(24 citation statements)

References 20 publications

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“…In accordance with the methodology described u Z ( 13) in the previous section, the power law flow equations are then solved for n and K , and the particular spinning conditions of interest, R 1 , R 2 , Z, r and Q , to yield the pressure drop, the velocity Combining eqs. ( 12 ) and ( 13) gives the following profile, the shear stress profile, and the shear rate expression, which is solved numerically for l by profile across the annulus during spinning.…”

Section: Establishing the Flow Profile In Practicementioning

confidence: 99%

See 1 more Smart Citation

Flow profile induced in spinneret during hollow fiber membrane spinning

Shilton

1997

J. Appl. Polym. Sci.

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A methodology is presented to establish the flow profile induced in a spinneret during the spinning of hollow fiber membranes. The flow equations are derived for a power law fluid passing through a concentric annulus. The pressure drop, the velocity profile, the shear stress profile, and the shear rate profile induced during spinning can then be determined. This type of rheological knowledge is useful if membrane structure and properties are to be related to the flow conditions experienced in the spinneret.

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Section: Establishing the Flow Profile In Practicementioning

confidence: 99%

“…The standardized velocity profile in the annulus is evaluated numerically from eqs. j normalized radius ( 12) and ( 13) . Using the velocity profile data the g acceleration due to gravity standardized volumetric flowrate, q , can in turn shear rate g h be numerically determined since …”

Section: Establishing the Flow Profile In Practicementioning

confidence: 99%

Flow profile induced in spinneret during hollow fiber membrane spinning

Shilton

1997

J. Appl. Polym. Sci.

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“…17,18 This observation has also been confirmed by using infrared reflection spectroscopy. [19][20][21] However, a quantitative analysis is needed to systematically study the effects of the flow conditions during spinning on the final morphology and properties of the hollow fiber membranes.…”

Section: Introductionmentioning

confidence: 99%

Power‐law polymer solution flow in a converging annular spinneret: Analytical approximation and numerical computation

Tung¹,

Li²,

Hu³

et al. 2011

AIChE Journal

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A simplified analytical solution for the flow of power-law liquids through a conical annulus was derived to estimate the flow profile, wall shear rate, and elongation rate in the spinneret during the spinning of hollow fiber membranes. The velocity profiles and shear and elongation rates of the power-law fluid showed good agreement with those obtained from computational fluid dynamic simulations. Although the actual spinneret is characterized by an annulus with a converging cross section, most studies to date have used a geometrical concentric annulus for the sake of simplicity. The results of the current work indicate that neglecting the converging characteristics of the actual spinneret can lead to significant underestimation of the wall shear rate. Using the equations derived in our work, we were able to predict not only the velocity profile but also the wall shear rate and the elongation rate; the influence of the spinneret design on the membrane morphology and properties were also examined.

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“…The development of hollow fiber membrane is more focused on the phase inversion factors such as relative exchange rate between the solvent and precipitant at the inner and outer surfaces of the nascent membrane, composition and temperature of external coagulant, composition of dope solution and composition, temperature and flow rate of the bore fluid. However, recently, fundamental researches have been focused on the effect of shear stress (rate) within the spinneret because it is recognized that the dope rheology does play a very important role in the process of hollow fiber membrane formation [1][2][3][4][5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…Since their spinning solution is a viscoelastic fluid, molecular orientation induced by shear stress within the spinneret might relax in the air gap region if the elongation stress along the spin line is small or enhance if the spin line stress is high. Ismail et al [8][9][10][11] also investigated the effect of shear rate on molecular orientation on skin layer of gas separation and reverse osmosis hollow fiber membrane by using plane-polarized infrared spectroscopy. Their results suggested that there was an increased molecular orientation in the high-sheared membrane that enhanced the gas selectivity and reverse osmosis rejection.…”

Section: Introductionmentioning

confidence: 99%