Molecular model for wall slip: Role of convective constraint release
Metadata of CSIR Papers
View Archive Info| Field | Value | |
| Title |
Molecular model for wall slip: Role of convective constraint release
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| Creator |
Joshi, YM
Lele, AK Mashelkar, RA |
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| Subject |
Polymer Science
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| Description |
A tube model is proposed for predicting wall slip phenomenon driven by the interfacial "disentanglement" mechanism. We model the dynamics of tethered chains, which are grafted on a high-energy wall and are entangled with the bulk chains flowing past them. The starting point of our model is the contour variable model (Mead; et al. Macromolecules 1998, 31, 7895), from which Ne develop a constitutive equation for tethered chains. We show that while the bulk chains are able to relax their orientation in the intermediate shear rate regime by the convective constraint release (CCR) mechanism, she tethered chains experience a highly restricted CCR that is unable to randomize its flow-induced orientation above a critical shear rate or stress. This decreases the resistance to flow for the bulk chains, which suddenly slip past the oriented tethered chains. The model correctly predicts the molecular weight dependence of the slip length, critical slip velocity and critical wall shear stress. It also quantitatively predicts the slip length and the critical slip velocity for a PDMS melt for which valuable molecular level experimental data are available in the literature.
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| Publisher |
AMER CHEMICAL SOCWASHINGTON1155 16TH ST, NW, WASHINGTON, DC 20036 USA
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| Date |
2011-09-24T08:41:38Z
2011-09-24T08:41:38Z 2001 |
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| Type |
Article
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| Identifier |
MACROMOLECULES
0024-9297 http://hdl.handle.net/123456789/24067 |
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| Language |
English
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