%0 journal article
%@ 0376-7388
%A Albrecht, W., Kneifel, K., Weigel, T., Hilke, R., Just, R., Schossig, M., Ebert, K., Lendlein, A.

%D 2005
%J Journal of Membrane Science
%N 1-2
%P 69-80 
%R doi:10.1016/j.memsci.2005.03.042
%T Preparation of highly asymmetric hollow fiber membranes from poly(ether imide) by a modified dry-wet phase inversion technique using a triple spinneret
%U https://doi.org/10.1016/j.memsci.2005.03.042
1-2 
%X Scanning electron microscopy (SEM) analysis of the morphology of poly(ether imide) (PEI) hollow fiber membranes prepared by a dry–wet spinning technology have been carried out. The results show that the outer layer of the extruded polymer solution can be precipitated by vapor induced phase separation (VIPS) resulting in relatively dense structures. In order to avoid VIPS, a modified air gap spinning process was developed using a triple spinneret where the outer annulus was used for transport of fluids containing a high amount of solvent. As a consequence of the presence of fluid at the outer surface of the nascent hollow fiber, the polymer concentration was locally reduced and the fiber was protected against the sorption of water vapor from the ambient atmosphere in the air gap. The results show that highly asymmetric hollow fiber morphologies without any external skin can be reproducibly prepared. Their separation properties are similar to those of conventionally prepared membranes but the permeability could be improved considerably due to a distinctly reduced support layer resistance.