Fundamental concepts coupled with practical, step-by-step guidance
With its emphasis on core principles, this text equips readers with the skills and knowledge to design the many processes needed to safely and successfully manufacture thermoplastic parts. The first half of the text sets forth the general theory and concepts underlying polymer processing, such as the viscoelastic response of polymeric fluids and diffusion and mass transfer. Next, the text explores specific practical aspects of polymer processing, including mixing, extrusion dies, and post-die processing. By addressing a broad range of design issues and methods, the authors demonstrate how to solve most common processing problems.
This Second Edition of the highly acclaimed Polymer Processing has been thoroughly updated to reflect current polymer processing issues and practices. New areas of coverage include:
- Micro-injection molding to produce objects weighing a fraction of a gram, such as miniature gears and biomedical devices
- New chapter dedicated to the recycling of thermoplastics and the processing of renewable polymers
- Life-cycle assessment, a systematic method for determining whether recycling is appropriate and which form of recycling is optimal
- Rheology of polymers containing fibers
Chapters feature problem sets, enabling readers to assess and reinforce their knowledge as they progress through the text. There are also special design problems throughout the text that reflect real-world polymer processing issues. A companion website features numerical subroutines as well as guidance for using MATLAB®, IMSL®, and Excel to solve the sample problems from the text. By providing both underlying theory and practical step-by-step guidance, Polymer Processing is recommended for students in chemical, mechanical, materials, and polymer engineering.
Table of Contents
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
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
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
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
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
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
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
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
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
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
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
