Melt‐spinning dynamics and rheological properties of nylon 6

Basic studies of the melt‐spinning dynamics and rheological properties of a nylon 6 polymer are described. The magnitude of the force components on the spinline has been analyzed with special reference to the drag and rheological forces. Spinline deformation has been investigated for spinning through ambient air and through an isothermal chamber. Both sets of experiments are interpreted using an elongational viscosity. Non‐Newtonian viscosity was measured at 230°, 250°, and 270°C in a Weissenberg rheogoniometer and an Instron capillary rheometer. The principal normal stress difference was measured in the former instrument. The rheological properties are interpreted in terms of the theory of viscoelastic fluid behavior. The isothermal melt‐spinning experiments were also interpreted in terms of the theory of viscoelastic fluids, and attempts were made to understand the spinning results in terms of basic rheological properties.