Plastics Engineering, 4e

Plastics Engineering, Fourth Edition, Presents Basic Essentials On The Properties And Processing Behaviour Of Plastics And Composites. The Book Gives Engineers And Technologists A Sound Understanding Of Basic Principles Without The Introduction Of Unduly Complex Levels Of Mathematics Or Chemistry. Early Chapters Discuss The Types Of Plastics Currently Available And Describe How Designers Select A Plastic For A Particular Application. Later Chapters Guide The Reader Through The Mechanical Behaviour Of Materials, Along With A Detailed Analysis Of Their Major Processing Techniques And Principles. All Techniques Are Illustrated With Numerous Worked Examples Within Each Chapter, With Further Problems Provided At The End. This Updated Edition Has Been Thoroughly Revised To Reflect Major Changes In Plastic Materials And Their Processing Techniques That Have Occurred Since The Previous Edition. The Plastics And Processing Techniques Addressed Within The Book Have Been Comprehensively Updated To Reflect Current Materials And Technologies, With New Worked Examples And Problems Also Included. Gives New Engineers And Technologists A Thorough Understanding Of The Essential Properties And Processing Behavior Of Plastics And Composites Presents A Great Source Of Foundational Information For Students, Early-career Engineers And Researchers Demonstrates How Basic Engineering Principles In Design, Mechanics Of Materials, Fluid Mechanics And Thermodynamics May Be Applied To The Properties, Processing And Performance Of Modern Plastic Materials Cover 1 Plastics Engineering 2 Copyright 3 Preface to the fourth edition 4 Preface to the third edition 496 Preface to the second edition 8 Preface to the first edition 9 1. General properties of plastics 11 1.1 Introduction 11 1.2 Polymeric materials 12 (a) Thermoplastic materials 15 (b) Thermosetting plastics 17 1.3 Plastics available to the designer 18 1.3.1 Commodity thermoplastics 18 1.3.2 Engineering thermoplastics 19 1.3.3 High performance plastics 20 1.3.4 Thermosets 20 1.3.5 Composites 21 1.3.6 Structural foam 23 1.3.7 Elastomers 24 1.3.8 Polymer alloys 27 1.3.9 Liquid crystal polymers 27 1.3.10 Shape memory polymers 28 1.3.11 Bio-degradable plastics 29 1.4 Selection of plastics 29 1.4.1 Mechanical properties 30 Material selection for strength 32 Material selection for stiffness 37 1.4.2 Degradation 39 Physical or chemical attack 39 1.4.3 Wear resistance and frictional properties 41 1.4.4 Thermal properties 44 1.4.5 Special properties 49 1.4.6 Processing 53 1.4.7 Recyclability 54 1.4.8 Costs 55 Selection for strength at minimum cost 55 Selection for stiffness at minimum cost 57 Typical Characteristics of Some Important Plastics 57 (a) Semi-crystalline plastics 57 (b) Amorphous plastics 62 (c) Thermoplastics rubbers (TPRs or TPEs) 64 (d) Thermosetting plastics 64 Bibliography 66 2 - Mechanical behaviour of plastics 606 2.1 Introduction 68 2.2 Viscoelastic behaviour of plastics 69 2.3 Short-term testing of plastics 70 2.4 Long-term testing of plastics 73 2.5 Design methods for plastics using deformation data 75 2.5.1 Isochronous and isometric graphs 75 2.5.2 Pseudo-elastic design method for plastics 80 2.6 Thermal stresses and strains 90 2.7 Multi-layer mouldings 94 2.8 Design of snap fits 99 2.9 Design of ribbed sections 103 2.10 Stiffening mechanisms in other moulding situations 110 2.11 Mathematical models of viscoelastic behaviour 112 2.11.1 Maxwell model 113 Stress–Strain Relations 113 Equilibrium Equation 113 Geometry of Deformation Equation 114 (i) Creep 114 (ii) Relaxation 115 (iii) Recovery 116 2.11.2 Kelvin or Voigt model 116 Stress–Strain Relations 116 Equilibrium Equation 116 Geometry of Deformation Equation 116 (i) Creep 117 (ii) Relaxation 118 (iii) Recovery 118 2.11.3 More complex models 119 2.11.4 Standard linear solid 122 Stress–Strain Relations 122 Equilibrium Equation 122 Geometry of Deformation Equation 123 (i) Creep 123 (ii) Relaxation 123 (iii) Recovery 124 2.12 Intermittent loading 125 2.12.1 Superposition principle 215 (a) Step Changes of Stress 125 (b) Continuous Changes of Stress 128 2.12.2 Empirical approach 134 2.13 Dynamic loading of plastics 140 2.14 Time–temperature superposition 147 2.15 Fracture behaviour of unreinforced plastics 150 2.16 The concept of stress concentration 151 2.17 Energy approach to fracture 152 2.18 Stress intensity factor approach to fracture 157 2.19 General fracture behaviour of plastics 162 2.20 Creep failure of plastics 165 2.20.1 Fracture mechanics approach to creep fracture 168 2.20.2 Crazing in plastics 168 2.21 Fatigue of plastics 169 2.21.1 Effect of cyclic frequency 171 2.21.2 Effect of waveform 173 2.21.3 Effect of testing control mode 174 2.21.4 Effect of mean stress 174 2.21.5 Effect of stress system 176 2.21.6 Fracture mechanics approach to fatigue 177 2.22 Impact behaviour of plastics 179 2.22.1 Effect of stress concentrations 179 2.22.2 Effect of temperature 182 2.22.3 Miscellaneous factors affecting impact 183 2.22.4 Impact test methods 183 2.22.5 Fracture mechanics approach to impact 185 Questions 189 Bibliography 202 3. Mechanical behaviour of composites 204 3.1 Deformation behaviour of reinforced plastics 204 3.2 Types of reinforcement 204 3.3 Types of matrix 207 (a) Thermosets 207 (b) Thermoplastics 207 3.4 Forms of fibre reinforcement in composites 208 3.5 Analysis of continuous fibre composites 209 (i) Longitudinal properties 209 Equilibrium equation 209 Geometry of deformation equation 210 Stress–strain relationships 210 (ii) Properties perpendicular to longitudinal axis 215 Equilibrium condition 215 Geometry of deformation equation 215 Stress–strain relations 216 3.6 Deformation behaviour of a single ply or lamina 218 (i) Loading on fibre axis 218 (ii) Loading off the fibre axis 221 3.7 Summary of approach to analysis of unidirectional composites 226 3.8 General deformation behaviour of a single ply 233 (i) Loading on fibre axis 233 (ii) Loading off fibre axis 236 3.9 Deformation behaviour of laminates 241 (i) Laminates made from unidirectional plies 241 In-plane behaviour of a symmetric laminate 241 3.10 Summary of steps to predict stiffness of symmetric laminates 244 3.11 General deformation behaviour of laminates 246 Convention for defining thicknesses and positions of plies 246 Analysis of laminates 247 3.12 Analysis of multi-layer isotropic materials 257 3.13 Analysis of non-symmetric laminates 262 3.14 Analysis of short fibre composites 265 (a) Fibre lengths less than lt 269 (b) Fibre length equal to lt 269 (c) Fibre length greater than lt 270 3.15 Creep behaviour of fibre reinforced plastics 272 3.16 Strength of fibre composites 272 3.16.1 Strength of single plies 274 (i) Maximum stress criterion 274 (ii) Maximum strain criterion 274 (iii) Tsai – Hill criterion 275 (a) Maximum stress criterion 275 (b) Maximum strain criterion 276 (c) Tsai-Hill criterion 276 3.16.2 Strength of laminates 276 3.17 Fatigue behaviour of reinforced plastics 278 3.18 Impact behaviour of reinforced plastics 280 Questions 280 Bibliography 285 4. Processing of plastics 287 4.1 Introduction 287 4.2 Extrusion 288 4.2.1 General features of single screw extrusion 288 (a) Feed zone 113 (b) Compression zone 289 (c) Metering zone 290 4.2.2 Mechanism of flow 294 4.2.3 Analysis of flow in extruder 295 4.2.4 Extruder/die characteristics 301 4.2.5 Other die geometries 302 4.2.6 General features of twin screw extruders 305 4.2.7 Processing methods based on the extruder 215 (a) Granule production/compounding 308 (b) Profile production 310 (c) Film extrusion 311 (d) Blow moulding 314 Extrusion blow moulding 314 Analysis of blow moulding 317 Extrusion stretch blow moulding 319 Injection stretch blow moulding 320 (e) Extrusion coating processes 320 (f) Fibre spinning 322 (g) Co-extrusion 323 (h) Biaxially orientated plastics 326 (i) Reactive extrusion 329 4.3 Injection moulding 329 4.3.1 Introduction 329 4.3.2 Details of the process 330 4.3.3 Moulds 337 (a) Gates 339 (b) Runners 340 (c) Sprues 341 (d) Venting 341 (e) Mould temperature control 341 Multi-daylight moulds 343 Hot runner moulds 344 Insulated runner moulds 346 Mould clamping force 346 4.3.4 Structural foam injection moulding 350 4.3.5 Sandwich moulding 352 4.3.6 Assisted injection moulding 448 4.3.7 Reaction injection moulding 356 4.3.8 Injection blow moulding 357 4.3.9 Injection moulding of thermosetting materials 359 4.3.10 Other advanced injection moulding technologies 361 (a) Micromoulding 361 (b) Overmoulding 362 (c) In-mould labelling 363 (d) Microcellular injection moulding 365 (e) Shear controlled orientation in injection mould (SCORIM) 365 4.4 Thermoforming 365 (a) Vacuum forming 368 (b) Pressure forming 371 (c) Plug-assisted thermoforming 372 (d) Matched die forming 374 (e) Twin-sheet thermoforming 374 4.4.1 Analysis of thermoforming 376 4.5 Calendering 380 4.5.1 Analysis of calendering 381 4.6 Rotational moulding 384 4.6.1 Slush moulding 390 4.7 Compression moulding 391 4.8 Transfer moulding 394 4.9 Additive manufacturing techniques 445 4.9.1 Stereolithography (SLA) 396 4.9.2 Fused filament fabrication (FFF) 397 4.9.3 Selective laser sintering (SLS) 398 4.9.4 Other 3D printing techniques 400 4.10 Processing reinforced thermoplastics 400 4.11 Processing reinforced thermosets 402 4.11.1 Manual processing methods 404 (a) Hand lay-up 404 (b) Spray-up 404 (c) Autoclave moulding 406 4.11.2 Semi-automatic processing methods 406 (a) Cold press moulding 406 (b) Hot press mouldings 407 (c) Resin injection 409 (d) Vacuum injection 410 4.11.3 Automatic processes 411 (a) Filament winding 411 (b) Centrifugal casting 412 (c) Pultrusion 412 (d) Injection moulding 413 Questions 413 Bibliography 621 5. Analysis of polymer melt flow 418 5.1 Introduction 418 5.2 General behaviour of polymer melts 419 5.3 Isothermal flow in channels: Newtonian fluids 421 (a) Flow of Newtonian fluid along a channel of uniform circular cross-section 421 (b) Flow of Newtonian fluid between parallel plates 424 5.4 Rheological models for polymer melt flow 426 5.5 Isothermal flow in channels: Non-Newtonian fluids 430 (a) Flow of power law fluid along a channel of uniform circular cross-section 209 (b) Flow of power law fluid between parallel plates 431 5.6 Isothermal flow in non-uniform channels 433 (a) Flow in coni-cylindrical dies 302 (i) Pressure drop due to shear, Ps 433 (ii) Drop due to extensional flow PE 435 (iii) Pressure drop at die entry, P0 436 (b) Flow in wedge shaped die 438 5.7 Elastic behaviour of polymer melts 439 5.7.1 Swelling ratios due to shear stresses 440 (a) Long capillary 440 (b) Long rectangular channel 441 5.7.2 Swelling ratio due to tensile stresses 442 (a) short capillary (zero length) 442 (b) Short rectangular channel 443 5.8 Residence and relaxation times 444 (a) Residence (or dwell) time 444 (b) Relaxation (or natural) time 445 5.9 Temperature rise in die 445 5.10 Experimental methods used to obtain flow data 446 5.10.1 Cone and plate viscometer 446 5.10.2 Concentric cylinder viscometer 448 5.10.3 Ram extruder 448 5.10.4 Melt Flow Rate (MFR) or Melt Flow Index (MFI) 452 5.10.5 Flow defects 453 5.11 Analysis of flow in some processing operations 454 (a) Elastic strain 468 (b) Viscous strain 469 5.12 Analysis of heat transfer during polymer processing 470 5.13 Calculation of clamping force 482 (a) Isothermal situation 482 (b) Non-isothermal situation 483 Questions 488 Bibliography 495 Solutions to questions 496 Appendix A - Structure of plastics 287 A.1 Structure of long molecules 592 A.2 Conformation of the molecular chain 593 A.3 Arrangement of molecular chains 597 Appendix B - Solution of differential equations 602 Appendix C - Stress/strain relationships 603 (i) Uniaxial stresses 204 (ii) Biaxial stresses 604 (iii) Triaxial stresses 605 Appendix D - Stresses in cylindrical shapes 606 Appendix E - Introduction to matrix algebra 608 E.1 Matrix definitions 608 E.2 Matrix multiplication 609 E.3 Matrix addition and subtraction 609 E.4 Inversion of a matrix 610 E.5 Symmetric matrix 610 Appendix F - Abbreviations for some common polymers 612 Index 614 A 614 B 614 C 615 D 616 E 617 F 617 G 618 H 618 I 618 K 619 L 619 M 620 N 621 O 621 P 621 R 623 S 624 T 625 U 626 V 626 W 626 X 626 Y 626 Z 626 Back Cover 627 Plastics Engineering, Fourth Edition, presents basic essentials on the properties and processing behaviour of plastics and composites. The book gives engineers and technologists a sound understanding of basic principles without the introduction of unduly complex levels of mathematics or chemistry. Early chapters discuss the types of plastics currently available and describe how designers select a plastic for a particular application. Later chapters guide the reader through the mechanical behaviour of materials, along with a detailed analysis of their major processing techniques and principles. All techniques are illustrated with numerous worked examples within each chapter, with further problems provided at the end.

This updated edition has been thoroughly revised to reflect major changes in plastic materials and their processing techniques that have occurred since the previous edition. The plastics and processing techniques addressed within the book have been comprehensively updated to reflect current materials and technologies, with new worked examples and problems also included.

• Gives new engineers and technologists a thorough understanding of the essential properties and processing behavior of plastics and composites
• Presents a great source of foundational information for students, early-career engineers and researchers
• Demonstrates how basic engineering principles in design, mechanics of materials, fluid mechanics and thermodynamics may be applied to the properties, processing and performance of modern plastic materials