Measuring and Predicting the Dynamics of Linear Monodisperse Entangled Polymers in Rapid Flow through an Abrupt Contraction. A Small Angle Neutron Scattering Study Export

@article{citeulike:2120068, abstract = {Small-angle neutron scattering measurements on a series of monodisperse linear entangled polystyrene melts in nonlinear flow through an abrupt 4:1 contraction have been made. Clear signatures of melt deformation and subsequent relaxation can be observed in the scattering patterns, which were taken along the centerline. These data are compared with the predictions of a recently derived molecular theory. Two levels of molecular theory are used: a detailed equation describing the evolution of molecular structure over all length scales relevant to the scattering data and a simplified version of the model, which is suitable for finite element computations. The velocity field for the complex melt flow is computed using the simplified model and scattering predictions are made by feeding these flow histories into the detailed model. The modeling quantitatively captures the full scattering intensity patterns over a broad range of data with independent variation of position within the contraction geometry, bulk flow rate and melt molecular weight. The study provides a strong, quantitative validation of current theoretical ideas concerning the microscopic dynamics of entangled polymers which builds upon existing comparisons with nonlinear mechanical stress data. Furthermore, we are able to confirm the appreciable length scale dependence of relaxation in polymer melts and highlight some wider implications of this phenomenon.}, address = {Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of Queensland, St. Lucia, Queensland 4072, Australia, and EPSRC, Polaris House, North Star Avenue, Swindon SN2 1ET, U.K.}, author = {Graham, R. S. and Bent, J. and Hutchings, L. R. and Richards, R. W. and Groves, D. J. and Embery, J. and Nicholson, T. M. and McLeish, T. C. B. and Likhtman, A. E. and Harlen, O. G. and Read, D. J. and Gough, T. and Spares, R. and Coates, P. D. and Grillo, I.}, citeulike-article-id = {2120068}, citeulike-linkout-0 = {http://dx.doi.org/10.1021/ma052357z}, citeulike-linkout-1 = {http://pubs.acs.org/doi/abs/10.1021/ma052357z}, day = {1}, doi = {10.1021/ma052357z}, journal = {Macromolecules}, keywords = {entanglement, flow, monodisperse}, month = {April}, number = {7}, pages = {2700--2709}, posted-at = {2009-10-21 06:10:50}, priority = {2}, title = {Measuring and Predicting the Dynamics of Linear Monodisperse Entangled Polymers in Rapid Flow through an Abrupt Contraction. A Small Angle Neutron Scattering Study}, url = {http://dx.doi.org/10.1021/ma052357z}, volume = {39}, year = {2006} }

TY - JOUR ID - citeulike:2120068 L3 - citeulike-article-id:2120068 N2 - Small-angle neutron scattering measurements on a series of monodisperse linear entangled polystyrene melts in nonlinear flow through an abrupt 4:1 contraction have been made. Clear signatures of melt deformation and subsequent relaxation can be observed in the scattering patterns, which were taken along the centerline. These data are compared with the predictions of a recently derived molecular theory. Two levels of molecular theory are used: a detailed equation describing the evolution of molecular structure over all length scales relevant to the scattering data and a simplified version of the model, which is suitable for finite element computations. The velocity field for the complex melt flow is computed using the simplified model and scattering predictions are made by feeding these flow histories into the detailed model. The modeling quantitatively captures the full scattering intensity patterns over a broad range of data with independent variation of position within the contraction geometry, bulk flow rate and melt molecular weight. The study provides a strong, quantitative validation of current theoretical ideas concerning the microscopic dynamics of entangled polymers which builds upon existing comparisons with nonlinear mechanical stress data. Furthermore, we are able to confirm the appreciable length scale dependence of relaxation in polymer melts and highlight some wider implications of this phenomenon. IS - 7 JF - Macromolecules AD - Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of Queensland, St. Lucia, Queensland 4072, Australia, and EPSRC, Polaris House, North Star Avenue, Swindon SN2 1ET, U.K. EP - 2709 TI - Measuring and Predicting the Dynamics of Linear Monodisperse Entangled Polymers in Rapid Flow through an Abrupt Contraction. A Small Angle Neutron Scattering Study VL - 39 SP - 2700 KW - entanglement KW - flow KW - monodisperse AU - Graham, RS AU - Bent, J AU - Hutchings, LR AU - Richards, RW AU - Groves, DJ AU - Embery, J AU - Nicholson, TM AU - McLeish, TCB AU - Likhtman, AE AU - Harlen, OG AU - Read, DJ AU - Gough, T AU - Spares, R AU - Coates, PD AU - Grillo, I PY - 2006/04/01/ UR - http://dx.doi.org/10.1021/ma052357z ER -