Rheology for Polymer Melt Processing (eBook)

Front Cover 1
Rheology for Polymer Melt Processing 4
Coppyright Page 5
Contents 8
Preface 6
PART I: MOLECULAR DYNAMICS 12
Chapter I.1. The reptation model : tests through diffusion measurements in linear polymer melts 12
Introduction 12
The reptation model 13
Diffusion measurements in polymer systems 17
Interpretation and comparison with rheometrical data 22
Conclusions 26
Chapter I.2. Polybutadiene : NMR and Temporary elasticity 28
Introduction 28
Temporary network structures 31
Segmental motions : dynamic screening effect 39
Molten high polymers : semi-local dynamics 44
Conclusion 46
Chapter I.3. Chain relaxation processes of uniaxially stretched polymer chains : an infrared dichroism study 48
Introduction 48
Theoretical background in Infrared dichroism 49
Experimental 50
Theoretical basis of interpretation 52
Results and discussion on isotopically labeled chains 55
Results and discussion on isotopically labelled 6-arm stars 60
Results and discussion on binary blends of long and short chains 66
Conclusion 72
Chapter I.4. Chain conformation in elongational and shear flow as seen by SANS 76
Introduction 76
Methodology 77
Elongational flow 84
Shear flow 98
Conclusions and perspectives 104
Chapter I.5. Molecular rheology and linear viscoelasticity 106
Introduction 106
Linear viscoelastic behaviour of linear and flexible chains - basics and phenomenology 107
The case of entangled monodisperse linear species : pure reptation 116
Entangled model-branched polymers 125
Entangled polydisperse linear chains : double reptation 130
Effects of non entangled chains 140
Problems still pending 146
PART II: CONSTITUTIVE EQUATIONS AND NUMERICAL MODELLING 152
Chapter II.1. Experimental validation of non linear network models 152
Introduction 152
Theoretical aspects 155
Experimental aspects 170
Experimental validation of the Wagner model 178
Experimental validation of the Phan Thien-Tanner model 187
Conclusion 186
Chapter II.2. Mathematical analysis of differential models for viscoelastic fluids 210
Introduction. The models 210
Maxwell type models : loss of evolution and change of type 212
Steady flows 214
Unsteady flows 219
Stability issues 225
Numerical analysis of viscoelastic flows 236
Conclusion 241
Chapter II.3. Computation of 2D viscoelastic flows for a differential constitutive equation 248
Introduction 248
Computation of a purely viscous flow 251
Finite elements method for viscoelastic flows 255
Application 263
Conclusion 263
PART III: SIMPLE AND COMPLEX FLOWS 268
Chapter III.1. Validity of the stress optical law and application of birefringence to polymer complex flows 268
Introduction 268
General relationships and usefulness of birefringence measurements 268
Validity of the stress optical law 275
Application to complex flow studies 288
Conclusion 292
Chapter III.2. Comparison between experimental data and numerical models 296
Introduction 296
Materials 300
Constitutive equations 300
Flow geometries and experiments 306
Numerical models 311
Comparison between numerical results and experiments 328
Conclusions 344
Chapter III.3. Slip at the wall 348
Introduction 348
Local determination of the velocity at the wall 349
Molecular models and discussion 359
Conclusions 364
Chapter III.4. Slip and friction of polymer melt flows 368
Introduction 368
Means used 370
Flow in high surface energy dies 372
Flow in dies with low surface energy 383
Discussion and conclusion 395
Chapter III.5. Stability phenomena during polymer melt extrusion 400
Introduction 400
Experimental facilities and flow curves 402
Visualization of upstream flow 408
Observation of stable flow - sharkskin 413
Observation of unstable flow for slightly to moderately entangled polymers - melt fracture 419
Highly entangled polymers - flow with slip 424
Conclusion 426
SUBJECT INDEX 432