EXTENSIONAL VISCOSITY MEASUREMENTS OF DILUTE-SOLUTIONS OF VARIOUS POLYMERS

Four constant and equal viscosity polymer solutions (Boger fluids) wer e constructed for comparable elongational property measurements. The c ommon constant viscosity of the solutions was 0.20 Pa s while four pol ymers were chosen to range from rigid and slender to flexible coiled a nd enlarged molecules in solution. Comparative elongational measuremen ts on the four solutions in the Newtonian (inelastic) solvents were ma de with a Rheometrics RFX opposed jet viscometer. The Trouton ratios o bserved for the polymer solvents and various water-glycerol solutions agreed to within +/- 30% of the expected Trouton ratio of 3, while the results for the rigid molecules in solution agreed with the Batchelor prediction based on the molecular aspect ratio determined independent ly for the polymer from light scattering measurements. This paper pres ents a direct comparison of extensional flow resistance of the several types of polymers: a rod-like polymer, a semi-rigid chain, a compact random coil, and a highly expanded random coil.