Diffusion during the coagulation step of wet‐spinning

Abstract The coagulation of viscous polymer solutions by diffusional interchange with a liquid bath is the key step to fiber formation by wet‐spinning. Model experiments were performed on gelled solutions of an acrylic polymer in dimethylacetamide, to determine the mass‐transfer rates of solvent and nonsolvent (water) during coagulation, the rate of movement of a boundary associated with coagulation, and the final equilibrium between the coagulated phase and the bath. Each is given as a function of bath composition and temperature. The data are analyzed by means of various diffusion models, one of them giving quite good agreement. The data and the models are used in conjunction with each other for the elucidation of the mechanism of the processes involved in coagulation.