Polymer membrane formation through the thermal-inversion process. 2. Mathematical modeling of membrane structure formation

Caneba, Gerard T.; Soong, David S.

doi:10.1021/ma00154a032

Cited by 102 publications

(66 citation statements)

References 13 publications

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“…Structural coarsening was reported by McMaster 4 for polymer blends phase-separated die swollen extrudate. Again, this is qualitatively consistent with the compositional data, although by both nucleation and growth and spinodal decomposition, while others 5,6 considered coarsenthe magnitude of the changes and exact timing do not coincide in each case. For instance, the swelling ing in the thermal demixing of a polymer/solvent system.…”

Section: Resultssupporting

confidence: 84%

Compositional changes during the wet spinning of acrylic fibers from aqueous sodium thiocyanate solvent

Law¹,

Mukhopadhyay²

1998

J. Appl. Polym. Sci.

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ABSTRACT:The compositional changes taking place during the wet spinning of acrylic fibers from an aqueous sodium thiocyanate solvent were investigated. The composition of the fibers diverted from the precipitation bath after various immersion times was determined gravimetrically, while fiber diameters were imaged to ascertain volumetric changes with time. The kinetics of phase separation were approximated using light transmission and video techniques applied to acrylic films. For coagulation into water at 20 and 40ЊC and into 15% aqueous NaSCN at 20ЊC, a greater influx of the nonsolvent to outflow of the solvent was recorded at short timescales. Unexpectedly, both the outflow of the solvent and nonsolvent against the concentration gradient was noted at longer timescales, suggested by the light transmission data to be after the primary phase separation. The consequent reduction in filament diameter, hence, the volume, is discussed in terms of a coarsening mechanism, whereby the mobile polymer lean phase has a route away from the filament into the bath during polymer coarsening. Finally, the compositional changes are plotted on a phase diagram for the system as trajectories into the two-phase region. The polymer-coarsening effect renders the interpretation at longer timescales uncertain.

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Section: Resultssupporting

confidence: 84%

Compositional changes during the wet spinning of acrylic fibers from aqueous sodium thiocyanate solvent

Law¹,

Mukhopadhyay²

1998

J. Appl. Polym. Sci.

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“…Examples of polymeric materials with anisotropic morphologies include anisotropic porous polymer membranes and switchable holographic PDLC films. [15,16] The structural anisotropy can be introduced by imposing an external fluctuation, such as an electric field, [17,18] a shear flow, [19] a concentration gradient, [15] a temperature gradient [20][21][22] or controlled chemical reaction [23][24][25][26] to the phase-separating polymeric systems. The PIPS method will be studied in this paper, for fabricating anisotropic polymeric materials by means of applying an external temperature gradient to the polymer solution.…”

Section: Introductionmentioning

confidence: 99%

A Computational Study of the Polymerization‐Induced Phase Separation Phenomenon in Polymer Solutions under a Temperature Gradient

Lee

Chan

Feng

2003

Macro Theory & Simulations

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This paper studied the polymerization‐induced phase separation phenomenon (spinodal decomposition) in a model binary polymer solution under a linear spatial temperature gradient for the purpose of fabricating anisotropic polymeric materials by using mathematical modeling and computer simulation. Reaction kinetics were incorporated with the non‐linear Cahn‐Hilliard theory and the Flory‐Huggins free energy expression in the model. Moreover, the slow mode theory and Rouse law were used to account for polymer diffusion. It was found that an anisotropic morphology was obtained when a temperature gradient was imposed along the polymer solution sample. The direction of the structural anisotropy, however, depended significantly on the overall phase separation time. The presence of a temperature gradient along the polymer solution sample generated a spatial variation in polymerization rate, which resulted in a spatial variation of quench depth. Consequently, at a given instant, the phase separation at different locations of the polymer solution was at different stages of spinodal decomposition. The droplet size formed along the polymer solution was therefore dependent on the polymerization rate, the quench depth and the stage of spinodal decomposition. Furthermore, the spatial temperature gradient produced a spatial variation in the process induction time, which contains the polymerization induction time and phase separation induction time. It was also found that the polymerization induction time played a significant role on the spatial variation in the overall process induction time.image

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“…This phenomenon, commonly known as coarsening, has been widely studied for systems comprised of low-molecularweight liquids (1)(2)(3), viscous and viscoelastic polymer blends (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16), oligomers (17)(18)(19)(20)(21)(22), metallic alloys (23,24), gas bubbles dispersed in a liquid medium (25,26), and polymer solutions 1 To whom correspondence should be addressed. (27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38). Most of these studies report a power law dependence of the mean domain size on the time since phase separation t, or a ∼ K t ξ , where K is a prefactor and ξ is the growth exponent.…”

Section: Introductionmentioning

confidence: 99%

Coalescence-Induced Coalescence of Inviscid Droplets in a Viscous Fluid

Martula

Hasegawa²,

Lloyd

et al. 2000

Journal of Colloid and Interface Science

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Polymer membrane formation through the thermal-inversion process. 2. Mathematical modeling of membrane structure formation

Cited by 102 publications

References 13 publications

Compositional changes during the wet spinning of acrylic fibers from aqueous sodium thiocyanate solvent

Compositional changes during the wet spinning of acrylic fibers from aqueous sodium thiocyanate solvent

A Computational Study of the Polymerization‐Induced Phase Separation Phenomenon in Polymer Solutions under a Temperature Gradient

Coalescence-Induced Coalescence of Inviscid Droplets in a Viscous Fluid

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