Steady spinning of the Oldroyd fluid B II: Experimental results

Isothermal fiber-spinning results have been obtained for an 1850 ppm solution of polyisobutylene with a constant viscosity of 360 poise and a relaxation time of 0.824 s. The steady and dynamic shear properties of this Boger fluid are well described by the Oldroyd B constitutive equation for shear rates less than 10 s⁻¹. Velocity profiles and spinline stresses were measured for a variety of fiber drawdown ratios, spinline lengths and for shear rates within the range of applicability of the Oldroyd B model. The results are compared with the theory developed in Part I [4], and excellent agreement is obtained when the effects of gravity were propertly taken into account. Indeed, this is the first time that the correct stress levels in the extensional flow of a highly viscoelastic polymer solution have been predicted from a knowledge of viscometric data alone using a simple three-parameter constitutive equation.