Polymer Processing
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Preface xi
Preface to the First Edition xiii
Acknowledgments xv
1 Importance of Process Design 1
1.1 Classification of Polymer Processes 1
1.2 Film Blowing: Case Study 5
1.3 Basics of Polymer Process Design 7
References 8
2 Isothermal Flow of Purely Viscous Non-Newtonian Fluids 9
Design Problem I Design of a Blow Molding Die 9
2.1 Viscous Behavior of Polymer Melts 10
2.2 One-Dimensional Isothermal Flows 13
2.2.1 Flow Through an Annular Die 14
2.2.2 Flow in a Wire Coating Die 17
2.3 Equations of Change for Isothermal Systems 19
2.4 Useful Approximations 26
2.5 Solution to Design Problem I 27
2.5.1 Lubrication Approximation Solution 27
2.5.2 Computer Solution 29
Problems 30
References 34
3 Viscoelastic Response of Polymeric Fluids and Fiber Suspensions 37
Design Problem II Design of a Parison Die for a Viscoelastic Fluid 37
3.1 Material Functions for Viscoelastic Fluids 38
3.1.1 Kinematics 38
3.1.2 Stress Tensor Components 39
3.1.3 Material Functions for Shear Flow 40
3.1.4 Shear-Free Flow Material Functions 43
3.2 Nonlinear Constitutive Equations 44
3.2.1 Description of Several Models 44
3.2.2 Fiber Suspensions 52
3.3 Rheometry 55
3.3.1 Shear Flow Measurements 56
3.3.2 Shear-Free Flow Measurements 58
3.4 Useful Relations for Material Functions 60
3.4.1 Effect of Molecular Weight 60
3.4.2 Relations Between Linear Viscoelastic Properties and Viscometric Functions 61
3.4.3 Branching 61
3.5 Rheological Measurements and Polymer Processability 62
3.6 Solution to Design Problem II 64
Problems 66
References 70
4 Diffusion and Mass Transfer 73
Design Problem III Design of a Dry-spinning System 73
4.1 Mass Transfer Fundamentals 74
4.1.1 Definitions of Concentrations and Velocities 74
4.1.2 Fluxes and Their Relationships 76
4.1.3 Fick's First Law of Diffusion 76
4.1.4 Microscopic Material Balance 78
4.1.5 Similarity with Heat Transfer: Simple Applications 80
4.2 Diffusivity! Solubility! and Permeability in Polymer Systems 84
4.2.1 Diffusivity and Solubility of Simple Gases 84
4.2.2 Permeability of Simple Gases and Permachor 87
4.2.3 Moisture Sorption and Diffusion 90
4.2.4 Permeation of Higher-Activity Permeants 90
4.2.5 Polymer-Polymer Diffusion 93
4.2.6 Measurement Techniques and Their Mathematics 94
4.3 Non-Fickian Transport 95
4.4 Mass Transfer Coefficients 96
4.4.1 Definitions 96
4.4.2 Analogies Between Heat and Mass Transfer 97
4.5 Solution to Design Problem III 99
Problems 101
References 108
5 Nonisothermal Aspects of Polymer Processing 111
Design Problem IV Casting of Polypropylene Film 111
5.1 Temperature Effects on Rheological Properties 111
5.2 The Energy Equation 113
5.2.1 Shell Energy Balances 113
5.2.2 Equation of Thermal Energy 117
5.3 Thermal Transport Properties 120
5.3.1 Homogeneous Polymer Systems 120
5.3.2 Thermal Properties of Composite Systems 123
5.4 Heating and Cooling of Nondeforming Polymeric Materials 124
5.4.1 Transient Heat Conduction in Nondeforming Systems 125
5.4.2 Heat Transfer Coefficients 130
5.4.3 Radiation Heat Transfer 132
5.5 Crystallization! Morphology! and Orientation 135
5.5.1 Crystallization in the Quiescent State 136
5.5.2 Other Factors Affecting Crystallization 142
5.5.3 Polymer Molecular Orientation 143
5.6 Solution to Design Problem IV 145
Problems 147
References 150
6 Mixing 153
Design Problem V Design of a Multilayered Extrusion Die 153
6.1 Description of Mixing 154
6.2 Characterization of the State of Mixture 156
6.2.1 Statistical Description of Mixing 157
6.2.2 Scale and Intensity of Segregation 161
6.2.3 Mixing Measurement Techniques 163
6.3 Striation Thickness and Laminar Mixing 164
6.3.1 Striation Thickness Reduction from Geometrical Arguments 164
6.3.2 Striation Thickness Reduction from Kinematical Arguments 169
6.3.3 Laminar Mixing in Simple Geometries 171
6.4 Residence Time and Strain Distributions 174
6.4.1 Residence Time Distribution 174
6.4.2 Strain Distribution 177
6.5 Dispersive Mixing 180
6.5.1 Dispersion of Agglomerates 180
6.5.2 Liquid-Liquid Dispersion 182
6.6 Thermodynamics of Mixing 188
6.7 Chaotic Mixing 189
6.8 Solution to Design Problem V 191
Problems 194
References 198
7 Extrusion Dies 201
Design Problem VI Coextrusion Blow Molding Die 201
7.1 Extrudate Nonuniformities 202
7.2 Viscoelastic Phenomena 203
7.2.1 Flow Behavior in Contractions 203
7.2.2 Extrusion Instabilities 203
7.2.3 Die Swell 207
7.3 Sheet and Film Dies 212
7.4 Annular Dies 216
7.4.1 Center-Fed Annular Dies 216
7.4.2 Side-Fed and Spiral Mandrel Dies 217
7.4.3 Wire Coating Dies 217
7.5 Profile Extrusion Dies 220
7.6 Multiple Layer Extrusion 222
7.6.1 General Considerations 222
7.6.2 Design Equations 224
7.6.3 Flow Instabilities in Multiple Layer Flow 227
7.7 Solution to Design Problem VI 228
Problems 230
References 234
8 Extruders 235
Design Problem VII Design of a Devolatilization Section for a Single-screw Extruder 235
8.1 Description of Extruders 235
8.1.1 Single-Screw Extruders 237
8.1.2 Twin-Screw Extruders 238
8.2 Hopper Design 239
8.3 Plasticating Single-Screw Extruders 242
8.3.1 Solids Transport 242
8.3.2 Delay and Melting Zones 246
8.3.3 Metering Section 250
8.4 Twin-Screw Extruders 253
8.4.1 Self-wiping Corotating Twin-Screw Extruders 253
8.4.2 Intermeshing Counterrotating Extruders 256
8.5 Mixing! Devolatilization! and Reactions in Extruders 258
8.5.1 Mixing 258
8.5.2 Devolatilization in Extruders 262
8.5.3 Reactive Extrusion 264
8.6 Solution to Design Problem VII 265
8.6.1 Dimensional Analysis 265
8.6.2 Diffusion Theory 267
Problems 268
References 272
9 Postdie Processing 275
Design Problem VIII Design of a Film Blowing Process for Garbage Bags 275
9.1 Fiber Spinning 276
9.1.1 Isothermal Newtonian Model 278
9.1.2 Nonisothermal Newtonian Model 281
9.1.3 Isothermal Viscoelastic Model 285
9.1.4 High-Speed Spinning and Structure Formation 287
9.1.5 Instabilities in Fiber Spinning 290
9.2 Film Casting and Stretching 293
9.2.1 Film Casting 293
9.2.2 Stability of Film Casting 296
9.2.3 Film Stretching and Properties 297
9.3 Film Blowing 297
9.3.1 Isothermal Newtonian Model 299
9.3.2 Nonisothermal Newtonian Model 302
9.3.3 Nonisothermal Non-Newtonian Model 303
9.3.4 Biaxial Stretching and Mechanical Properties 304
9.3.5 Stability of Film Blowing 304
9.3.6 Scaleup 305
9.4 Solution to Design Problem VIII 305
Problems 306
References 308
10 Molding and Forming 311
Design Problem IX Design of a Compression Molding Process 311
10.1 Injection Molding 311
10.1.1 General Aspects of Injection Molding 311
10.1.2 Simulation of Injection Molding 315
10.1.3 Microinjection Molding 318
10.2 Compression Molding 319
10.2.1 General Aspects of Compression Molding 319
10.2.2 Simulation of Compression Molding 320
10.3 Thermoforming 322
10.3.1 General Aspects of Thermoforming 322
10.3.2 Modeling of Thermoforming 324
10.4 Blow Molding 328
10.4.1 Technological Aspects of Blow Molding 328
10.4.2 Simulation of Blow Molding 330
10.5 Solution to Design Problem IX 332
Problems 335
References 340
11 Process Engineering for Recycled and Renewable Polymers 343
11.1 Life-Cycle Assessment 343
11.2 Primary Recycling 348
11.3 Mechanical or Secondary Recycling 351
11.3.1 Rheology of Mixed Systems 352
11.3.2 Filtration 352
11.4 Tertiary or Feedstock Recycling 354
11.5 Renewable Polymers and Their Processability 357
11.5.1 Thermal Stability and Processing of Renewable Polymers 358
Problems 362
References 363
Nomenclature 365
Appendix A Rheological Data for Several Polymer Melts 373
Appendix B Physical Properties and Friction Coefficients for Some Common Polymers in the Bulk State 379
Appendix C Thermal Properties of Materials 381
Appendix D Conversion Table 385
Index 387
