No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
The full text of this article is not currently available.
Elucidating the flow-microstructure coupling in entangled polymer melts. Part II: Molecular mechanism of shear banding
Mohagheghi, M. , and B. Khomami, “ Elucidating the flow-microstructure coupling in highly entangled polymer melts. Part I: Single chain dynamics in shear flow,” J. Rheol. 60, 849–859 (2016).
Doi, M. , and S. F. Edwards, “ Dynamics of concentrated polymer systems. Part 4: Rheological properties,” J. Chem. Soc., Faraday Trans. 2 75, 38–54 (1979).
Osaki, K. , and M. Kurata, “ Experimental appraisal of the Doi-Edwards theory for polymer rheology based on the data for polystyrene solutions,” Macromolecules 13, 671–676 (1980).
Vrentas, C. M. , and W. W. Graessley, “ Study of shear stress relaxation in well ‐ characterized polymer liquids,” J. Rheol. 26, 359–371 (1982).
Marrucci, G. , and N. Grizzuti, “ Study of shear stress relaxation in well ‐ characterized polymer liquids,” J. Rheol. 27, 433–450 (1983).
Morrison, F. A. , and R. G. Larson, “ A study of shear-stress relaxation anomalies in binary mixtures of monodisperse polystyrenes,” J. Polym. Sci. Part B: Polym. Phys. 30, 943–950 (1992).
Venerus, D. C. , and R. Nair, “ Stress relaxation dynamics of an entangled polystyrene solution following step strain flow,” J. Rheol. 50, 59–75 (2006).
Wang, S.-Q. , S. Ravindranath, P. Boukany, M. Olechnowicz, R. P. Quirk, A. Halasa, and J. Mays, “ Nonquiescent relaxation in entangled polymer liquids after step shear,” Phys. Rev. Lett. 97, 187801 (2006).
Hu, Y. T. , L. Wilen, A. Philips, and A. Lips, “ Is the constitutive relation for entangled polymers monotonic?,” J. Rheol. 51, 275–295 (2007).
Boukany, P. E. , Y. T. Hu, and S.-Q. Wang, “ Observations of wall slip and shear banding in an entangled DNA solution,” Macromolecules 41, 2644–2650 (2008).
Ravindranath, S. , and S.-Q. Wang, “ Large amplitude oscillatory shear behavior of entangled polymer solutions: Particle tracking velocimetric investigation,” J. Rheol. 52, 341–358 (2008).
Ravindranath, S. , S.-Q. Wang, M. Olechnowicz, and R. P. Quirk, “ Banding in simple steady shear of entangled polymer solutions,” Macromolecules 41, 2663–2670 (2008).
Boukany, P. E. , and S.-Q. Wang, “ Exploring the transition from wall slip to bulk shearing banding in well-entangled DNA solutions,” Soft Matter 5, 780–789 (2009).
Boukany, P. E. , S.-Q. Wang, and X. Wang, “ Step shear of entangled linear polymer melts: New experimental evidence for elastic yielding,” Macromolecules 42, 6261–6269 (2009).
Boukany, P. E. , and S.-Q. Wang, “ Shear banding or not in entangled DNA solutions depending on the level of entanglement,” J. Rheol. 53, 73–83 (2009).
Ravindranath, S. , and S.-Q. Wang, “ What are the origins of stress relaxation behaviors in step shear of entangled polymer solutions?,” Macromolecules 40, 8031–8039 (2007).
Adams, J. M. , S. M. Fielding, and P. D. Olmsted, “ Transient shear banding in entangled polymers: A study using the Rolie-Poly model,” J. Rheol. 55, 1007–1032 (2011).
Olmsted, P. D. , O. Radulescu, and C.-Y. D. Lu, “ Johnson–Segalman model with a diffusion term in cylindrical Couette flow,” J. Rheol. 44, 257–275 (2000).
Likhtman, A. E. , and R. S. Graham, “ Simple constitutive equation for linear polymer melts derived from molecular theory: Rolie–Poly equation,” J. Non-Newtonian Fluid Mech. 114, 1–12 (2003).
Su, Y. Y. , and B. Khomami, “ Purely elastic interfacial instabilities in superposed flow of polymeric fluids,” Rheol. Acta 31, 413–420 (1992).
Su, Y. Y. , and B. Khomami, “ Interfacial stability of multilayer viscoelastic fluids in slit and converging channel die geometries,” J. Rheol. 36, 357–387 (1992).
Ganpule, H. K. , and B. Khomami, “ An investigation of interfacial instabilities in the superposed channel flow of viscoelastic fluids,” J. Non-Newtonian Fluid Mech. 81, 27–69 (1999).
Cheng, S. , and S.-Q. Wang, “ Is shear banding a metastable property of well-entangled polymer solutions?,” J. Rheol. 56, 1413–1428 (2012).
Article metrics loading...
In this study, we have elucidated the molecular origin of shear banding in the entangled polymeric melts. Specifically, it is shown that the inflection point corresponding to the stress-overshoot indicates the possibility of inhomogeneity and this combined with slow orientation relaxation in step-strain start-up experiments will lead to formation of local inhomogeneity along the velocity gradient direction. Once the aforementioned inhomogeneities are created, a localized jump in entanglement density and a commensurate jump in normal stress and viscosity will lead to formation of the incipient shear banded flow structure. To this end, number of step-strain and start-up simulations with different deformation rate ramp times in the planar Couette flow with entanglement densities ⟨Zk⟩ ≥ 17 were performed to demonstrate the effect of deformation rate ramp time on the formation of local inhomogeneities and occurrence of shear banding. It has been demonstrated that if the time scale for the deformation rate to reach its steady value is larger or on the order of the orientation relaxation time of the chain, local inhomogeneities in the velocity gradient direction will not form and the linear velocity profile will prevail. Overall, the molecular mechanism of incipient shear banding as well as its evolution to steady shear banding or to a linear velocity profile (transient shear banding) is described for the first time. Moreover, our findings are in agreement with a host of prior step-strain and start-up experiments with synthetic and natural Deoxyribonucleic acid (DNA) entangled polymeric
Full text loading...
Most read this month