An alternative approach to non-isothermal melt spinning with axial and radial viscosity distributions

Abstract It is shown that non-isothermal melt spinning with axial as well as radial viscosity distributions can be considered as a particular case of the flows with dominating extensions discussed elsewhere. Such viscosity distributions may be caused by axial and radial temperature gradients and crystallization effects in the spinline. The corresponding solutions are obtained for Newtonian and slightly non-Newtonian fluids by means of a perturbation method for weak variability of the extensional viscosity function. The validity of the so-called quasi-elongational approximation, widely used in numerous references, is also discussed. It is proved, moreover, that, independently of the magnitude of viscosity gradients, velocity profiles across the filament are always convex and any “skin effects” do not appear at all.