Effect of ethanol composition in water coagulation bath on morphology of PVDF hollow fibre membranes

Polyvinylidene fluoride (PVDF) hollow fibre membranes were spun from 20% PVDF (Kynar(R) k-760) in N,N-dimethylacetamide (DMAc) by a dry-jet-wet spinning technique. Polyvinyl-pyrrolidine (PVP) was used as a pore-forming additive. Effect of coagulation medium, ethanol (10-50%) and water (90-50%), on the morphology of the PVDF hollow fibre membranes was studied using SEM. The gas permeation method was used to estimate the surface pore size and effective surface porosity of the PVDF hollow fibre membrane prepared. An attempt has been made to correlate the effect of composition of ethanol:water coagulation medium on membrane morphology with factors like the solubility parameter and diffusivity of solvent and nonsolvent used in the preparation of the hollow fibre membranes. (C) 1998 Elsevier Science B.V. All rights reserved.