Two-dimensional modeling of polymer wet spinning: The effects of mass transfer dynamics on structural properties

ABSTRACT In this work, a two‐dimensional model of polymer wet spinning that couples simultaneous momentum and energy transport with ternary diffusion and phase separation processes is presented and its predictions for a model system are discussed. The uniqueness of the model lies in its two‐phase nature and ability to predict important characteristics of the wet spinning process, such as the locking‐in of axial velocity, mass transfer behavior, and internal structure formation along the spinline. The model predicts growth of the two‐phase gel that forms and the porous fractions within it, along with the compositions of the polymer‐rich and solvent‐nonsolvent‐rich phases. The appearance of a skin‐core structure that depends on the system and operating conditions is also predicted. These features are demonstrated through analyses of the isothermal wet spinning of poly(acrylonitrile) solutions in dimethlysulfoxide using two different nonsolvent coagulants, water and ethanol. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41772.