| Abstract: | The pressure required to cause a spinning solution to flow through the spinnerette hole in a wet-spinning process has been found to decrease as the take-up velocity V1 is increased. The amount of pressure reduction from free extrusion, where V1 = Vf, to V1 denoted by p(Vf)–p(V1) was found to correlate well with the term (V1–Vf)/Vf. The pressure reduction is interpreted as the change in axial tensile stress of the solution within the capillary brought about by take-up of the filament, and the latter term is interpreted as a meaure of the strain state of the filament. For large hole diameters, plots of these measures of stress and strain are linear and independent of hole diameter, capillary length and configuration, and shear rate but depend on factors that affect basic rheological and coagulation characteristics of the system. At smaller hole sizes, the situation is somewhat more complex. Aspects of the fiber formation process are discussed in light of these observations. |
