Effect of fluid viscoelasticity on the draw resonance dynamics of melt spinning

The effect of fluid viscoelasticity on the draw resonance dynamics of melt spinning has been examined using White-Metzner and Phan Thien-Tanner fluid models into the governing equations of the process, in a continued effort to study the effects of process conditions and material properties on draw resonance, following up the earlier study [J. Non-Newtonian Fluid Mech. 87 (1999) 165] dealing with the effect of spinline cooling on the same draw resonance. Whether or not the fluid viscoelasticity stabilizes melt spinning has turned out to coincide with whether or not the spinline tension sensitivity decreases with the increasing fluid viscoelasticity. This is because the spinning stability is always enhanced by a decrease in tension sensitivity to process disturbances and this tension sensitivity was then found in the said earlier study to be moving opposite to the level of the spinline tension: The higher spinline tension, the smaller tension sensitivity. It has been found in the present study that the effect of fluid viscoelasticity on spinning stability can be classified into two diametrically different kinds: For extension-thickening fluids an increasing in viscoelasticity increases tension, decreases tension sensitivity and, thus, stabilizes the spinning, whereas it decreases tension, increases tension sensitivity and, thus, destabilizes the spinning of extension-thinning fluids.