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Highlights: [•] A mass transfer model for forced convection spinning has been developed. [•] The model contributes to the understanding of skin growth and the role of molecular orientation. [•] The model is a general utility to help analyse any dry/wet spinning system. [Copyright &y& Elsevier]

Forced convection spinning of polysulfone gas separation hollow fibre membranes was investigated. Spinneret geometry, spinning solution composition, extrusion shear, bore fluid rate, and forced convection residence time and gas rate were considered. A mass transfer model of the forced convection process was developed to help understand the effect of spinning conditions on membrane properties. Membrane pressure-normalised fluxes, selectivities and bursting pressures were discussed in terms of this new model and in terms of induced molecular orientation, polymer solution relaxation time, phase inversion (in particular skin formation) and membrane fine structural details as deduced by resistance modelling of gas transmission. [Copyright &y& Elsevier]

In order to elucidate the relationship between the dope extrusion shear rate and membrane performance, sodium chloride transfer through the asymmetric cellulose acetate reverse osmosis hollow fiber membranes is modeled, allowing fine details of the fiber structure to be deduced from the NaCl–H2O rejection characteristics. The structural information such as the pore size radius and skin thickness of the active layer deduced from the sodium chloride separation experimental data and surface force–pore flow model (SF–PF) is then used to interpret the relationship between the rheological conditions during spinning and membrane performance. The modeling results revealed that increased extrusion shear rate would decrease both pore size and thickness of the active layer, thus increasing the separation performance of the RO hollow fiber membranes. [Copyright &y& Elsevier]

Cellulose acetate spinning solution used to produce reverse osmosis (RO) hollow fiber membranes was rheologically assessed using a rotational rheometer and an optical shear cell. Rheology measurements which involved flow curves were carried out so as to obtain the values of power law coefficients, n and k. The power law behaviour, normal force and flow profiles generated provided clues regarding phase inversion and molecular orientation. These rheological results are then correlated to the performance of cellulose acetate RO hollow fibers spun at different extrusion shear rates. The results suggest that extrusion shear is linked indirectly to phase inversion through induced molecular orientation, which in turn, affects the subsequent dry/wet precipitation stages in spinning. As the extrusion shear rate increases, the level of shear experienced at the walls of the spinneret also increases, thus leading to greater molecular orientation, resulting in membranes with higher rejection and flux rates. [Copyright &y& Elsevier]