دورية أكاديمية
The diffusion coefficient of a reptating polymer.
| العنوان: | The diffusion coefficient of a reptating polymer. |
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| المؤلفون: | Deutsch, J. M., Madden, T. L. |
| المصدر: | Journal of Chemical Physics; 9/1/1989, Vol. 91 Issue 5, p3252, 6p |
| مصطلحات موضوعية: | DIFFUSION, POLYMERS |
| مستخلص: | The dynamics of a polymer in a network of entanglements is studied. The viscosity has been examined for chains up to 50 links and is found to scale with chain length L as L3.41±0.14 in agreement with previous theoretical work, that attributes this anomalous exponent as a finite size effect because of the finite tube length. Numerical results for chains up to 100 links give that the diffusion coefficient D, scales as L-2.50±0.04. This result differs from theoretical predictions based on tube fluctuations which claim finite length effects are unimportant for diffusion and therefore imply a -2 power law dependence for D. The reason for this discrepancy is examined. Previous work used a one-dimensional rather than a three-dimensional diffusion coefficient as the starting point of analysis. By deriving the correct procedure for calculating the three-dimensional D, one sees that it has corrections to its asymptotic behavior which are quite large, of order L-1/2, rather than L-1 as was thought previously. This suggests that fluctuations in the tube length cannot provide an adequate explanation for the experimental data. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: | Complementary Index |
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