Development of a defect-free 6FDA-durene asymmetric hollow fiber and its composite hollow fibers

Chung, Tai‐Shung; Kafchinski, E. Ronald; Vora, Rohitkumar H.

doi:10.1016/0376-7388(93)e0163-e

Cited by 87 publications

(35 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These aspects include the composition of the dope solution, the composition of the bore liquid and external coagulant, quench conditions, the air gap length, bore fluid flow rate, humidity, and fiber take-up speed. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] When the polymer dope is pumped through the spinneret during hollow fiber spinning, the highest shear stress is located at the wall of the spinneret. Thus, the rheological conditions existing in the spinneret during hollow fiber spinning are essential to control the final membrane morphology and properties.…”

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

View full text Add to dashboard Cite

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.

show abstract

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

View full text Add to dashboard Cite

show abstract

“…In addition, the spinning dope suitable for fabriasymmetric hollow fibers, 6 Koros and Pinnau's [University of Texas (UT)] extrathin asymmetric cating hollow fibers generally has a much greater viscosity and elasticity than that for flat memflat membranes, 7 and Hoechst Celanese' integrally skinned asymmetric and multilayer combranes. Furthermore, the phase inversion process for hollow-fiber formation usually takes place posite membranes 8,9 are examples of many latest inventions in membrane technology.…”

Section: Introductionmentioning

confidence: 99%

Effect of air-gap distance on the morphology and thermal properties of polyethersulfone hollow fibers

Chung

1997

J. Appl. Polym. Sci.

Self Cite

154

View full text Add to dashboard Cite

By using 30/70 polyethersulfone/NMP ( N-methyl-2-pyrrolidone) solutions as an example, we have determined the role of air-gap distance on nascent fiber morphology, performance, and thermal properties. An increase in air-gap distance results in a hollow fiber with a less layer of fingerlike voids and a significant lower permeance. For the first time we have reported that the T g of a dry-jet wet-spun fiber prepared from one-polymer/one-solvent systems is lower than that of a wet-spun fiber, and T g decreases with an increase in air-gap distance. These interesting phenomena arise from the fact that different precipitation paths take place during the wet-spinning and dry-jet wet-spinning processes. Wet-spun fibers experience vigorous and almost instantaneous coagulations; it results in hollow fiber skins with a long-range random, unoriented chain entanglement, but loose structure. Dry-jet wet-spun fibers first go through a moisture-induced phase separation process and then a wet-phase inversion process; it results in external fiber skins with a short-range random, compact, and slightly oriented or stretched structure. As a result, the outskin of wet-spun fibers have a greater free volume and a higher first T g than that of the dry-jet wet-spun ones. Both SEM (scanning electronic microscope) photomicrographs and DSC (differential scanning calorimeter) analyses support our conclusion.

show abstract

“…Usually, water is the preferred external coagulant because of low cost and being environmentally friendly. The proper choice of the internal coagulant is, therefore, becoming very important because the rate of demixing (i.e., phase separation) and the resultant inner skin morphology strongly depend on the chemistry and compositions of the internal coagulant (Chung et al, 1992(Chung et al, , 1994.…”

Section: Basic Understandingmentioning

confidence: 99%

“…The residual solvents may redissolve the skin and densify the selective layer. The difference in solubility parameter between spinning solution and internal or external coagulant affect the coagulation rate (Kesting, 1985;Ho and Sirkar, 1992;Chung et al, 1992Chung et al, , 1994Matsuura, 1994). In addition, the ratio (k) of solvent outflow to coagulant influx determines the macroscopic membrane porosity McHugh, 1986, 1988;Matsuura, 1994), as illustrated in Figure 31.2.…”

Section: Basic Understandingmentioning

confidence: 99%

Fabrication of Hollow‐Fiber Membranes by Phase Inversion

Chung

2008

Advanced Membrane Technology and Applications

View full text Add to dashboard Cite

Development of a defect-free 6FDA-durene asymmetric hollow fiber and its composite hollow fibers

Cited by 87 publications

References 19 publications

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

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

Effect of air-gap distance on the morphology and thermal properties of polyethersulfone hollow fibers

Fabrication of Hollow‐Fiber Membranes by Phase Inversion

Contact Info

Product

Resources

About