Dynamics of stiff-chain polymers in isotropic solution. 2. Viscosity of aqueous solutions of xanthan, a rigid double-helical polysaccharide

✍ Scribed by Takada, Yasushi; Sato, Takahiro; Teramoto, Akio

• Book ID: 126911109
• Publisher: American Chemical Society
• Year: 1991
• Tongue: English
• Weight: 601 KB
• Volume: 24
• Category: Article
• ISSN: 0024-9297
• DOI: 10.1021/ma00023a024

✦ Synopsis

Zero-shear viscosities 90 of aqueous solutions of a rigid double-helical polysaccharide xanthan with 0.1 M NaCl were measured over a wide range of polymer concentration c from dilute through isotropic concentrated using eight fractionated samples ranging in the number N of Kuhn's statistical segments from 0.25 to 11.6. The strong polymer concentration and molecular weight M dependences of 70 measured could not be described by simple power laws. In contrast with concentrated flexible polymer solutions, the slope of the plot of log 90 vs log M at fixed c exceeded 3.4 at high M. The data of 70 for all the samples were compared with the viscosity equation for rodlike polymers previously derived. The viscosity equation could describe the data for the two lowest molecular weight samples ( N 5 0.4) but not for the other samples ( N > 0.8). This was taken to show an importance of finite stiffness in the solution viscosity. In spite of the remarkable electrostatic interaction on thermodynamic properties, the viscosity underwent no such effect.