Nonlinear Polymer Rheology

Preface Acknowledgments Introduction PART ONE: LINEAR VISCOELASTICITY AND EXPERIMENTAL METHODS 1. Phenomenological description of linear viscoelasticity (LVE) 1.1 Basic modes of deformation 1.2 Linear responses 1.3 Classical rubber elasticity theory 2. Molecular characterization in LVE regime 2.1 Dilute limit 2.2 Entangled state 2.3 Molecular-level descriptions of entanglement dynamics 2.4 Temperature dependence3. Experimental Methods 3.1 Shear rheometry 3.2 Extensional rheometry 3.3 Rheo-optical (in situ) methods 3.4 Advanced rheometric methods 4. Characterization of deformation field 4.1 Basic features in simple shear 4.2 Yield stress in Bingham type (yield-stress) fluids 4.3 Cases of homogeneous shear 4.4 Particle tracking velocimetry (PTV) 4.5 Single molecule imaging velocimetry (SMIV) 4.6 Other visualization methods 5. Improved and other rheometric apparatuses 5.1 Linearly displaced co-cylinder for simple shear 5.2 Cone-partitioned plate for rotational shear 5.3 Other forms of large deformation 5.4 Conclusion PART TWO: YIELDING - PRIMARY NONLINEAR RESPONSES TO ONGOING DEFORMATION 6. Wall slip - Interfacial yielding 6.1 Basic notion of wall slip in steady shear 6.2 Stick-slip transition (in stress-controlled mode 6.3 Wall slip during startup shear - Interfacial yielding 6.4 Relationship between slip and bulk shear deformation 6.5 Molecular evidence of disentanglement during wall slip 6.6 Uncertainty in boundary condition 6.7 Conclusion 7. Yielding during startup deformation: from elastic deformation to flow 7.1 Yielding at Wi 1 7.2 Stress overshoot in fast startup shear 7.3 Nature of steady shear 7.4 From terminal flow to fast flow under creep: entanglement-disentanglement transition 7.5 Yielding in startup uniaxial extension 7.6 Conclusion 8. Strain hardening in extension 8.1 Conceptual pictures 8.2 Origin of "strain hardening" in uniaxial extension 8.3 True strain hardening: non-Gaussian stretching from finite extensibility 8.4 Different responses of entanglement to startup extension and shear 8.5 Conclusion Appendix 8.A: Conceptual and mathematical account of geometric condensation 9. Shear banding in startup and oscillatory shear: PTV observations 9.1 Shear banding after overshoot in startup shear 9.2 Overcoming wall slip during startup shear 9.3 Shear banding in LAO 10. Strain localization in pressure-driven extrusion, squeezing, and planar extension 10.1 Capillary rheometry in rate-controlled mode 10.2 Instabilities at die entry 10.3 Squeezing deformation 10.4 Planar extension 11. Different modes of structural failure during startup uniaxial extension 11.1 Tensile-like failure (decohesion) at low rates 11.2 Shear yielding and necking-like strain localization at high rates 11.3 Rupture without crosslinking at even higher rates: where is disentanglement? 11.4 Strain localization vs. steady-flow: Sentmanat extensional rheometry vs. Filament stretching rheometry 11.5 Role of long chain branching Appendix 11.A: Analogy between capillary rheometry and filament stretching rheometry PART THREE: DECOHESION AND ELASTIC YIELDING AFTER LARGE DEFORMATION 12. Elastic yielding in stepwise simple shear 12.1 Strain softening after large step strain 12.2 PTV revelation of non-quiescent relaxation: localized elastic yielding 12.3 Quiescent elastic yielding 12.4 Arrested wall slip: elastic yielding at interfaces 12.5 Conclusion 13. Elastic breakup in stepwise uniaxial extension 13.1 Rupture-like failure during relaxation at small magnitude or small rate (WiR 13.2 Shear-yielding induced failure upon fast large stepwise extension (WiR > 1) 13.3 Nature of the elastic breakup probed by infrared thermal imaging measurements 13.4 Primitive phenomenological explanations 13.5 Stepwise squeeze and planar extension 14. Finite cohesion and the role of chain architecture 14.1 Cohesive strength of an entanglement network 14.2 Enhancing cohesion barrier with long-chain branching to prevent structural breakup PART FOUR: EMERGING CONCEPTUAL FRAMEWORK 15. Homogeneous entanglement 15.1 What is chain entanglement? 15.2 When, how and why disentanglement occurs 15.3 Criterion for homogeneous shear 15.4 Constitutive non-monotonicity 15.5 Metastable nature of shear banding 16. Molecular networks as the conceptual foundation 16.1 Introduction: the tube model and its predictions 16.2 Essential ingredients in formulation of a new molecular picture 16.3 Overcoming finite cohesion after step deformation: Quiescent or not 16.4 Forced microscopic yielding during startup deformation: stress overshoot 16.5 Interfacial yielding by disentanglement 16.6 Effect of long chain branching 16.7 Decohesion in startup creep: entanglement-disentanglement transition 16.8 Emerging microscopic theory of Sussman and Schweizer 16.9 Further tests to reveal the nature of polymer deformation 16.10 Conclusion 17. "Anomalous" phenomena 17.1 Essence of rheometric measurements: isothermal condition 17.2 Internal energy buildup and non-Gaussian extension 17.3 Breakdown of time-temperature superposition during transient response: shear and extension 17.4 Strain hardening in simple shear of certain polymer solutions 17.5 Lack of universal nonlinear responses: solutions vs. melts 17.6 Emergence of transient glassy responses 18. Difficulties with orthodox paradigams 18.1 Tube model does not to predict key experimental features 18.2 Confusion about local and global deformation 18.3 Molecular network paradigm 19. Strain localization and the fluid mechanics of polymeric liquids 19.1 Relationship between wall slip and banding: a rheological-state diagram 19.2 Modeling of continuum fluid mechanics of entangled polymeric liquids 19.3 Challenges in polymer processing 20. Conclusions 20.1 Theoretical challenges 20.2 Experimental difficulties Index