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Star polymer diffusion in concentrated solutions: Dependence on functionality via the coupling model

✍ Scribed by K. L. Ngai; A. K. Rajagopal; T. P. Lodge

Publisher
John Wiley and Sons
Year
1990
Tongue
English
Weight
547 KB
Volume
28
Category
Article
ISSN
0887-6266

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✦ Synopsis

Abstract

The coupling model is formulated in terms of the dynamic constraint entropy, S~c~(t), and subsequently compared with measured tracer diffusion coefficients D for linear, 3‐arm star, and 12arm star polystyrenes in solutions of poly (vinyl methyl ether) (PVME) /o‐fluorotoluene. Inequalities between the dynamic constraint entropies, S~cf~ and S~cfβ€²~(t), respectively, for f‐arm and f′‐arm stars, enable us to explain the experimental observation that at constant arm molecular weight, the ratio D~star~/D~linear~ decreases substantially with increasing concentration above the entanglement concentration for the PVME. This work indicates that not only the reptation model, but also the coupling model, can account for the experimental observation that in entangled solutions the mechanism for diffusion depends on diffusant architecture.

πŸ“œ SIMILAR VOLUMES

The effect of concentration on diffusion
The effect of concentration on diffusion coefficient in polymer solutions
✍ Robert M. Secor πŸ“‚ Article πŸ“… 1965 πŸ› American Institute of Chemical Engineers 🌐 English βš– 527 KB

A, is partitioned as shown by the cross hatching and modified to produce the second base case A, of Figure 6. The cycle is now pseudo node a indicated in Figure 4. Operations are continued up to k ' when another cycle is located consisting of nodes 9, 10, 12, and pseudo node a. A? is partitioned an