Membrane formation via phase separation induced by penetration of nonsolvent from vapor phase. II. Membrane morphology

Phase separation of poly(vinylidene fluoride) dimethylformamide solution was induced by the penetration of water vapor, and the porous membrane was formed. As the humidity in the gas phase increased, membrane morphology changed in the order of dense, porous (cellular), and lacy-like structures. At the higher humidity condition, spherical bead structure was observed, which is likely to be crystalline spherulite. With the increase of the initial polymer concentration, less pores were formed in the case of the lower humidity of 20%, whereas more distinguished spherical structures were formed in the case of higher humidity of 40%. The obtained membrane morphologies were discussed based on both the calculated composition paths during the process and the phase diagram. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 171–178, 1999

[1]  Hideto Matsuyama,et al.  Membrane formation via phase separation induced by penetration of nonsolvent from vapor phase. I. Phase diagram and mass transfer process , 1999 .

[2]  C. Tsay,et al.  Mass transfer modeling of asymmetric membrane formation by phase inversion , 1990 .

[3]  H. Matsuyama,et al.  Membrane formation and structure development by dry-cast process , 1997 .

[4]  L. Cheng,et al.  Isothermal phase behavior of Nylon‐6, ‐66, and ‐610 polyamides in formic acid–water systems , 1994 .

[5]  L. Cheng,et al.  An improved model for mass transfer during the formation of polymeric membranes by the immersion-precipitation process , 1994 .

[6]  S. Hwang,et al.  Formation of asymmetric polysulfone membranes by immersion precipitation. Part I. Modelling mass transport during gelation , 1992 .

[7]  C. A. Smolders,et al.  Diffusion induced phase separation with crystallizable nylons. I. Mass transfer processes for nylon 4,6 , 1996 .

[8]  Jan Feijen,et al.  Phase-Separation Processes in Polymer-Solutions in Relation to Membrane Formation , 1996 .

[9]  C. A. Smolders,et al.  Formation of membranes by means of immersion precipitation : Part I. A model to describe mass transfer during immersion precipitation , 1987 .

[10]  P. Flory.  Principles of polymer chemistry , 1953 .

[11]  S. Prager,et al.  Diffusion‐controlled formation of porous structures in ternary polymer systems , 1979 .

[12]  C. A. Smolders,et al.  Calculation of liquid-liquid phase separation in a ternary system of a polymer in a mixture of a solvent and a nonsolvent , 1982 .

[13]  C. A. Smolders,et al.  Equilibrium thermodynamics of the ternary membrane-forming system nylon, formic acid and water , 1996 .

[14]  W. Krantz,et al.  Dense polymer film and membrane formation via the dry-cast process part I. Model development , 1994 .

[15]  Marcel Mulder,et al.  Basic Principles of Membrane Technology , 1991 .

[16]  L. Cheng,et al.  Membrane formation by isothermal precipitation in polyamide‐formic acid‐water systems II. Precipitation dynamics , 1995 .

[17]  J. Feijen,et al.  Metastable Liquid-Liquid and Solid-Liquid Phase Boundaries in Polymer-Solvent-Nonsolvent Systems , 1997 .