ISSN:
0887-6266
Keywords:
integrally-skinned asymmetric membranes
;
skin layer formation
;
dry/wet phase inversion process
;
capillary pressure
;
surface tension
;
coalescence
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Optimized membranes made by a dry/wet phase inversion process using forced-convective evaporation consist of an ultrathin and pore-free skin layer supported by a nodular transition layer underlying open-cell, sponge-like substructure. It is suggested that the out-ermost region of such case membranes undergo phase separation by spinodal decomposition in the initial stages of the evaporation process. As a result of the small scale of phase separation present in polymer-solvent systems, an appreciable capillary pressure occurs in the interstitial space filled with the polymer-poor phase in contact with air. The resulting force acts normal to the membrane-air interface, which tends to consolidate the polymer-rich phase to form a nonporous surface layer. © 1993 John Wiley & Sons, Inc.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/polb.1993.090310406
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