On rheological properties of polydisperse polymers

✍ Scribed by A.Ya. Malkin; N.K. Blinova; G.V. Vinogradov; M.P. Zabugina; O.Yu. Sabsai; V.C. Shalganova; I.Yu. Kirchevskaya; V.P. Shatalov

• Publisher: Elsevier Science
• Year: 1974
• Tongue: English
• Weight: 547 KB
• Volume: 10
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(74)90210-9

✦ Synopsis

An investigation has been carried out into the effect of the fractional composition on the rheological (flow and elastic) properties of a system, using mixtures of polybutadienes with narrow molecularweight distribution (MWD). For mixtures of high-molecular-weight components, the initial Newtonian viscosity is determined by the weight-average molecular weight: r/0 ~ M~,; when low-molecular weight components are introduced, it is also determined by the MWD moment ratio. The characteristic relaxation time of a system is determined by the z-average molecular weight: 00 ~ 1~1~, and in the general ease ~q ~ -,. A new model has been proposed to explain the non-Newtonian phenomenon as a consequence of the existence of a molecular-weight distribution. According to this model, as the shear rate increases the high-molecular-weight components gradually (at their critical rates) pass over to the high-elastic state. Therefore, at high shear rates, their contribution to viscous losses of a polydisperse polymer is associated with their behaviour as a viscoelastic filler in a viscous liquid.