Elongational behaviour of dilute polymer solutions

Experimental results concerned with the elongational behaviour of dilute polymer solutions were presented. The elongational viscosity was measured as a function of the strain rate for all aqueous solution of the neutral polymer PAA-T19 anti for an aqueous 0.2 mol/l NaCl solution of the ionic pol mer Sedipur AF 701. Flow induced birefringence was monitored simultaneously in order to assess the orientation of the polymer molecules. A critical strain rate epsilon (over dot)* depending on the type of polymer solution separates two flow regions: a Newtonian region of strain independent elongational viscosity and a region with markedly and continuously increasing elongational viscosity Calculations applying the FENE dumbbell model were shown to he in good accordance with the experimental results of the non-ionic solution. Experimental data for the pipe friction fatter lambda as a function of the Re number are presented for both solutions and are discussed in connection with the elongational viscosity results.