Formation of asymmetric polysulfone membranes by immersion precipitation. Part II. The effects of casting solution and gelation bath compositions on membrane structure and skin formation

Radovanovic, Philip; Thiel, Stephen W.; Hwang, Sun‐Tak

doi:10.1016/0376-7388(92)87025-s

Cited by 137 publications

(41 citation statements)

References 8 publications

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“…Since the asymmetric-type membranes were prepared by Loeb and Sourirajan, the development of the phase inversion technique has preceded many systematic studies on the effects of membrane formation parameters and mechanism. Surface properties of membranes can be controlled depending on the casting conditions, 4 -6 polymer solution, [7][8][9][10][11] and coagulation bath compositions. 11 The pore-forming processes occurring in the phase inversion process contain both the thermodynamics [12][13][14][15][16] and kinetics [17][18][19] of the polymer solution systems.…”

Section: Introductionmentioning

confidence: 99%

Formation of integrally skinned asymmetric polyetherimide nanofiltration membranes by phase inversion process

Kim

Yoon

Lee

2002

J of Applied Polymer Sci

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ABSTRACT:Integrally skinned asymmetric polyetherimide (PEI) membranes were prepared by the phase inversion process from casting solution containing dimethylformamide (DMF) as a solvent and 1,4-dioxane as a cosolvent. Deionized water was used as a coagulation medium in preparing asymmetric membranes. The effect of 1,4-dioxane was investigated by measuring casting solution properties, permeation properties, and membrane structures. Various effects of polymer concentration, evaporation time, and coagulation bath temperature were also studied. Low miscibility of 1,4-dioxane with coagulant (water) resulted in reducing membrane pore size. The molecular weight cutoff values of asymmetric membranes could be controlled by changing the amount of 1,4-dioxane in the casting solution.

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Section: Introductionmentioning

confidence: 99%

Formation of integrally skinned asymmetric polyetherimide nanofiltration membranes by phase inversion process

Kim

Yoon

Lee

2002

J of Applied Polymer Sci

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“…Polar liquids, like water or alcohol, are used as coagulation bath because they are miscible with NMMO and cause NMMO removal from the cellulose solution. It is expected that the regeneration of cellulose-NMMOwater solutions follows the well known principles of phase separation in polymer solutions valid in membrane formation, Koenhen et al (1977), Broens et al (1980), Shen and Cabasso (1982), Radovanovic et al (1992), Pereira Nunes and Inoue (1996), Tsay and McHugh (1992), Barton et al (1997).…”

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confidence: 99%

Morphology of cellulose objects regenerated from cellulose–N-methylmorpholine N-oxide–water solutions

Biganska

Navard

2008

Cellulose

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The precipitation in aqueous media of cellulose from solutions in N-methylmorpholine Noxide (NMMO) hydrates is an important stage in the process of manufacturing of fibres, films and other cellulose objects. It is responsible for the formation of the structure of the regenerated object and their morphological characteristics significantly influence the properties of the final products. Regeneration of rather large cellulose objects was observed in situ by optical microscopy. It was found that all regenerated objects present an asymmetric structure composed of a dense skin surrounding a sub-layer characterised by the presence of finger-like voids. The porous texture of the cellulose parts between these voids is typical of the one obtained by spinodal decomposition. The morphologies of regenerated cellulose samples are described as a function of various parameters, initial cellulose solutions and composition and temperature of the aqueous regeneration bath. A mechanism of the structure formation during regeneration is proposed.

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“…Asymmetric membranes are mostly fabricated by a process called phase inversion, which can be achieved through four principal methods: immersion precipitation (wet-casting) [1][2][3][4], vapor-induced phase separation [5,6], thermally-induced phase separation [2,7], and dry-casting [8]. In all these techniques, an initially homogeneous polymer solution thermodynamically becomes unstable due to different external effects and phase separates into polymer lean and polymer rich phases.…”

Section: Introductionmentioning

confidence: 99%

Modeling of asymmetric membrane formation by dry-casting method

Altınkaya

Ozbas

2004

Journal of Membrane Science

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Many polymeric membranes are produced by phase inversion technique invented by Loeb and Sourirajan in 1962. The dry-casting method is one of the major phase inversion techniques in which a homogeneous polymer solution consisting of solvent(s) and nonsolvent(s) is cast on a support and then evaporation of the casting solution takes place under convective conditions. In this paper, we model membrane formation by the dry-casting method. The model takes into account film shrinkage, evaporative cooling, coupled heat, and mass transfer and incorporates practical and reliable diffusion theory as well as complex boundary conditions especially at the polymer solution/air interface. The predictions from the model provide composition paths, temperature, and thickness of the solution. By plotting the composition paths on the ternary phase diagram, we ascertain the general structural characteristics of the membranes prepared from particular casting conditions. The predictive ability of the model was evaluated by comparing the results with the experimental data obtained from gravimetric measurements for cellulose acetate (CA)-acetone-water system. In an attempt to illustrate the importance of diffusion formalism on the predictions, recently proposed multicomponent diffusion theory and its simplified forms were utilized in the model. The computational results show that the critical factor for capturing the accurate behavior of membrane formation is the diffusion formalism utilized in the model.

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Formation of asymmetric polysulfone membranes by immersion precipitation. Part II. The effects of casting solution and gelation bath compositions on membrane structure and skin formation

Cited by 137 publications

References 8 publications

Formation of integrally skinned asymmetric polyetherimide nanofiltration membranes by phase inversion process

Formation of integrally skinned asymmetric polyetherimide nanofiltration membranes by phase inversion process

Morphology of cellulose objects regenerated from cellulose–N-methylmorpholine N-oxide–water solutions

Modeling of asymmetric membrane formation by dry-casting method

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