Polysulfone gas separation hollow fiber membranes were manufactured using a
dry/wet spinning process with forced convection in the dry gap. Hollow fib
ers were produced using two different bore coagulants: one pure water and o
ne with reduced water activity. An optimized multi-component dope was used
which proved to be a shear-thinning power-law fluid. For each bore system,
membranes were spun at low and high dope extrusion rates (DERs) correspondi
ng to shear rates of around 4000 s(-1) and 10 000 s(-1), respectively, at t
he outer spinneret wall. Plane polarized infrared spectroscopy was used to
probe the membrane active layer. Pressure-normalized fluxes and selectiviti
es were evaluated using purl carbon dioxide and methane. For the spinning c
onditions used here, the combination of reduced water activity in the bore
and high DER produced highly selective membranes. Some selectivities reache
d about three times the recognized intrinsic value for the polymer. (C) 199
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