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ORAL PRESENTATION
Session: 4 Complex fluid deformation and rheology: Theories and thermodynamic relationships
(scheduled: Tuesday, 14:00 )
A general methodology to predict the linear rheology of branched polymers
E. van Ruymbeke1, R. Keunings2, C. Bailly2, D. Vlassopoulos1,3
1 IESL - FORTH, Heraklion, Greece
2 UCL, Louvain La Neuve, Belgium
3 University of Crete, Department of Materials Science and Technology, Heraklion, Greece
We present a general coarse-grained model for predicting the linear viscoelasic properties of branched polymers from the knowledge of their molecular structure and three viscoelastic parameters, i.e. the Rouse time of an entanglement segment, the plateau modulus and the entanglement molecular weight. The model uses the ingredients of the tube-based theories of McLeish and co-workers, and its implementation is based on a time-marching algorithm, this conceptual approach was already successfully applied to linear and star polymers, and is appropriately modified here to account for more complex branched architectures, within the framework of dynamic tube dilation (using the extended criteria of Graessley). While the fluctuations of the external branches segments are quite well described in literature, the motion of the molecular segments localized between two branching points is still an open question that we study in this work. With proper account of polydispersity and use of macromolecular coordinates for the diffusion of the branching points, successful description of a wide range of rheological data of H, pom-pom, tree-like or comb polymers is obtained. The good quality of predictions gives us confidence about this approach. More notably, we do not need to use ad hoc parameter modifications (in particular the p2 parameter) to get good results. The proposed methodology thus represents a generic approach for predicting the linear rheology of branched polymers. © IWNET 2006
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and Kleanthi for IWNET 2006