Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 357990
Title A constitutive model with moderate chain stretch for linear polymer melts
Author(s) Tchesnokov, M.A.; Molenaar, J.; Slot, J.J.M.; Stepanyan, R.
Source Journal of Non-Newtonian Fluid Mechanics 123 (2004)2-3. - ISSN 0377-0257 - p. 185 - 199.
DOI https://doi.org/10.1016/j.jnnfm.2004.08.007
Department(s) Mathematical and Statistical Methods - Biometris
PE&RC
Publication type Refereed Article in a scientific journal
Publication year 2004
Keyword(s) convective constraint release - cox-merz rule - entangled polymers - microscopic theory - polystyrene solutions - molecular theory - fast flows - shear - reptation - predictions
Abstract In our previous publication, we presented a molecular model to describe the dynamics of the interfacial layer between a flowing polymer melt and a die wall. We showed that the ensemble-averaged behavior of polymer molecules adsorbed on the wall could be successfully described in terms of the so-called bond vector probability distribution function (BVPDF). The BVPDF couples the chain orientation and chain stretch on the level of single segment, and thus is an extension of the orientation distribution function of Doi and Edwards introduced for inextensible chains. In this paper, the developed formalism is extended to molecules in the polymer bulk. We show how the well-known Doi and Edwards theory (DE) for inextensible chains based on the orientation distribution function can be naturally extended to include chain stretch and (convective) constraint release (CCR). The final constitutive equation accounts for such mechanisms on polymer chains as reptation, retraction, convection, contour length fluctuations, and (convective) constraint release. It is valid for both linear and non-linear flow regimes. The proposed theory is quantitative, and contains the same input parameters as the original DE model. As an application of the full theory, a simple equation of motion for the stress tensor is derived. Despite the simplicity, its predictions are found to be in good agreement with available experimental data over a wide range of flow regimes and histories.
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