Formation of membranes by means of immersion precipitation : Part II. the mechanism of formation of membranes prepared from the system cellulose acetate-acetone-water

A.J. Reuvers, C.A. Smolders

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Abstract

Using equations and boundary conditions derived in Part I1, calculations have been performed on the ternary diffusion processes that occur in a cellulose acetate (CA) -acetone casting solution immersed into a water bath. The necessary concentration-dependent thermodynamic and hydrodynamic parameters have been derived from experimental data on the three limiting binary mixtures. Calculations show that immersion of the polymer solution into the coagulation bath results in an instantaneous increase of the polymer concentration at the surface of the solution. For a CA-acetone casting solution the thickness of this concentrated surface layer will increase until the onset of liquid-liquid demixing by means of nucleation and growth of the diluted phase that fixes the asymmetric polymer distribution in the film. The moment of onset of the demixing process depends on the thickness of the film. However, addition of a certain minimum amount of water to the casting solution results in an instantaneous onset of liquid-liquid demixing upon immersion, yielding a membrane with a very thin skin layer. The model calculations have been confirmed by light transmission measurements performed on immersed casting solutions.
Original languageUndefined
Pages (from-to)67-86
JournalJournal of membrane science
Volume34
Issue number1
DOIs
Publication statusPublished - 1987

Keywords

  • IR-67261

Cite this

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title = "Formation of membranes by means of immersion precipitation : Part II. the mechanism of formation of membranes prepared from the system cellulose acetate-acetone-water",
abstract = "Using equations and boundary conditions derived in Part I1, calculations have been performed on the ternary diffusion processes that occur in a cellulose acetate (CA) -acetone casting solution immersed into a water bath. The necessary concentration-dependent thermodynamic and hydrodynamic parameters have been derived from experimental data on the three limiting binary mixtures. Calculations show that immersion of the polymer solution into the coagulation bath results in an instantaneous increase of the polymer concentration at the surface of the solution. For a CA-acetone casting solution the thickness of this concentrated surface layer will increase until the onset of liquid-liquid demixing by means of nucleation and growth of the diluted phase that fixes the asymmetric polymer distribution in the film. The moment of onset of the demixing process depends on the thickness of the film. However, addition of a certain minimum amount of water to the casting solution results in an instantaneous onset of liquid-liquid demixing upon immersion, yielding a membrane with a very thin skin layer. The model calculations have been confirmed by light transmission measurements performed on immersed casting solutions.",
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year = "1987",
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volume = "34",
pages = "67--86",
journal = "Journal of membrane science",
issn = "0376-7388",
publisher = "Elsevier",
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Formation of membranes by means of immersion precipitation : Part II. the mechanism of formation of membranes prepared from the system cellulose acetate-acetone-water. / Reuvers, A.J.; Smolders, C.A.

In: Journal of membrane science, Vol. 34, No. 1, 1987, p. 67-86.

Research output: Contribution to journalArticleAcademic

TY - JOUR

T1 - Formation of membranes by means of immersion precipitation : Part II. the mechanism of formation of membranes prepared from the system cellulose acetate-acetone-water

AU - Reuvers, A.J.

AU - Smolders, C.A.

PY - 1987

Y1 - 1987

N2 - Using equations and boundary conditions derived in Part I1, calculations have been performed on the ternary diffusion processes that occur in a cellulose acetate (CA) -acetone casting solution immersed into a water bath. The necessary concentration-dependent thermodynamic and hydrodynamic parameters have been derived from experimental data on the three limiting binary mixtures. Calculations show that immersion of the polymer solution into the coagulation bath results in an instantaneous increase of the polymer concentration at the surface of the solution. For a CA-acetone casting solution the thickness of this concentrated surface layer will increase until the onset of liquid-liquid demixing by means of nucleation and growth of the diluted phase that fixes the asymmetric polymer distribution in the film. The moment of onset of the demixing process depends on the thickness of the film. However, addition of a certain minimum amount of water to the casting solution results in an instantaneous onset of liquid-liquid demixing upon immersion, yielding a membrane with a very thin skin layer. The model calculations have been confirmed by light transmission measurements performed on immersed casting solutions.

AB - Using equations and boundary conditions derived in Part I1, calculations have been performed on the ternary diffusion processes that occur in a cellulose acetate (CA) -acetone casting solution immersed into a water bath. The necessary concentration-dependent thermodynamic and hydrodynamic parameters have been derived from experimental data on the three limiting binary mixtures. Calculations show that immersion of the polymer solution into the coagulation bath results in an instantaneous increase of the polymer concentration at the surface of the solution. For a CA-acetone casting solution the thickness of this concentrated surface layer will increase until the onset of liquid-liquid demixing by means of nucleation and growth of the diluted phase that fixes the asymmetric polymer distribution in the film. The moment of onset of the demixing process depends on the thickness of the film. However, addition of a certain minimum amount of water to the casting solution results in an instantaneous onset of liquid-liquid demixing upon immersion, yielding a membrane with a very thin skin layer. The model calculations have been confirmed by light transmission measurements performed on immersed casting solutions.

KW - IR-67261

U2 - 10.1016/S0376-7388(00)80021-6

DO - 10.1016/S0376-7388(00)80021-6

M3 - Article

VL - 34

SP - 67

EP - 86

JO - Journal of membrane science

JF - Journal of membrane science

SN - 0376-7388

IS - 1

ER -