Dynamics of polymeric fluids in transient-state theory

✍ Scribed by Junhua Wu

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 636 KB
• Volume: 61
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19960705)61:1<21::aid-app3>3.0.co;2-w

✦ Synopsis

Transient-state theory recently proposed has enabled us to describe the chain length dependence of viscosity of polymeric melts from the Rouse to entangling regimes by the single equation which also takes the factor of temperature into account. On the basis of this theory, this contribution attempts to treat the effect of temperature on viscosity and provides a molecular explanation to the coefficients of M-dependence in the WLF equation, obtaining the activation energy AEo and elastic interaction parameter a for example selected. A reinterpretation from a molecular viewpoint directly leads to the common observation of the M-dependence of the glass transition temperature. The mathematical expressions are developed for diffusion coefficient D,, showing the scaling behavior for special cases as M-' and M-2.4 below and above the entanglement coupling mass Me, respectively. Any deviation from the scaling can be accounted by the quantum confinement effect a. The terminal relaxation time T~ behaves in the same way as 7 above the onset of entanglement. It is found that both D, and rD scale on temperature in the way analogous to the WLF correlation. In addition, an expression for Young's modulus is presented by a molecular deduction. The predictions are in consistence with existing experimental data via the adjustment of a which can correlate more findings difficult to be accommodated into conventional theories.