Two-dimensional modeling of dry spinning of polymer fibers

Predictions of the dynamics of dry spinning of polymer fibers based on a two-dimensional model are presented. The constitutive equation used to describe the spinning fluid includes both viscous and viscoelastic effects and is based on an equivalent parallel combination of a non-linear Giesekus equation and a simple Newtonian component. Temperature and composition effects are accounted for in the viscosity, glass transition, and zero-shear modulus, and through these, in the associated relaxation time of the constitutive model. Inclusion of the viscous component enables predictions of the distinction between locking-in of the fiber velocity profile due to the rapidly rising viscosity and consequently dropping deformation rate, and fiber solidification due to the occurrence of a glass transition. Predictions of the axial and radial profiles of temperature, composition, stress, and orientation reflect the occurrence of skin-core morphology. Moreover, the single free parameter in the model, representing the ratio of the Newtonian component viscosity to that of the total viscosity, affects the fiber force profiles, and most especially the fiber axial velocity profile, and can therefore be used as a fitting parameter for spinline data.