(142cf) Linear Viscoelastic Properties of Salt-Tolerant HPAM Solutions with Ultrahigh Molecular Weight

In this paper, the linear viscoelastic properties of salt-tolerant partially hydrolyzed polyacrylamide (HPAM) solutions with ultrahigh molecular weight are presented. By means of strain sweep, frequency sweep and time sweep using Haake Rheostress 150 rheometer, the dynamic measurements of HPAM solutions with ultrahigh molecular weight are investigated comprehensively, and the concentration of solutions range from 3000 mg·L^-1 to 7000 mg·L^-1. The results show that the HPAM solutions are linear-viscoelastic when the strain is 0<γ<50% at the angular velocity of 1 rad/s and all the HPAM solutions show shear thinning flow behavior in the oscillatory frequency range of 0.01-10 Hz. Secondly, different from the HPAM solutions with low molecular weight and low concentration, the tested solutions show a greater elastic modulus than viscous modulus throughout the whole frequency range investigated, plus, according to a three-zone model for viscoelastic liquids, the dynamic rheological behaviors of all the HPAM solutions are assigned to plateau zone. Finally, the elastic modulus and viscous modulus increase exponentially with the increase of HPAM solution concentration.