MASS-TRANSFER AND THERMODYNAMICS DURING IMMERSION PRECIPITATION FOR A2-POLYMER SYSTEM - EVALUATION WITH THE SYSTEM PES-PVP-NMP-WATER

An extended version of the mass transfer model by Reuvers et al. for a four-component system is evaluated, which is shown to be generally va lid for short times. The thermodynamics under these circumstances are evaluated, together with the kinetics. Initial composition paths (conc entration profiles) are calculated. It appears that delay of demixing is not possible when a polymeric additive is used, which is soluble in the nonsolvent, while the velocity of demixing decreases. The calcula tions are evaluated for the system poly(ether )-poly(vinylpyrrolidone) -N-methylpyrrolidone-water by means of light transmission measurements during immersion precipitation, for a wide range of compositions of t he polymer solution and coagulation bath.