Crystallization Modalities in Polymer Melt Processing

4e de couverture : In addition to structure formation in crystallizing polymers and semicrystalline polymers, this second edition completes the topic of transport phenomena. It also reviews solidification by crystallization during cooling and under flow or pressure, which all play an enormous role in polymer melt processing. Generally, there is an intensive interaction between three transport phenomena: heat transfer, momentum transfer (flow, rheology) and (flow induced) crystallization. The strong interaction between the three transport phenomena is a major challenge when it comes to experimentation, and advances in this area are detailed in the book, guiding further development of sound modeling. This book enables readers to follow an advanced course in polymer processing. It is a valuable resource for polymer chemists, applied physicists, rheologists, plastics engineers, mold makers and material scientists Preface to the Second Edition 5 Preface to the First Edition 7 Contents 10 About the Author 12 1 Required Basic Achievements 13 1.1 Interaction of Three Transport Phenomena: Heat Transfer, Flow and Crystallization Kinetics 13 1.2 Available Theories Describing the Crystallization Process 18 1.2.1 The Kolmogoroff-Avrami-Evans Theory 18 1.2.2 The Rate Equations of Schneider, Köppl and Berger 24 1.3 Examples for Special Cases 28 1.3.1 Minimum Cooling Speed for by-Passing Crystallization, Eder [28] 28 1.3.2 A Dimensionless Process Classification Number 31 1.3.3 Scanning Calorimetry 35 1.3.3.1 Unabridged Simulation 35 1.3.3.2 A Simplified Analytical Solution 39 1.3.3.3 Scanning Micro-Calorimeter for High Cooling Rates 45 1.3.4 Phenomena of Propagation and Spreading 48 1.3.4.1 Fast Crystallizing Polymers 48 1.3.4.2 Theory of the Front Growth 52 1.3.4.3 Correctly Quenching a Polymer at a Metal Wall [48] 55 1.4 Crystallization in Confined Spaces 61 1.4.1 A Derivation of Kolmogoroff’s Equation According to G. Eder, Enabling a Generalization 62 1.4.2 Behavior of Confined Samples 65 1.4.2.1 Isothermal Case for a Slab of Constant Thickness 68 1.4.2.2 Significance of the Avrami Index 69 1.4.2.3 Some Final Remarks 72 1.5 Influence of Strong Temperature Gradients 74 1.5.1 Growth of Spherulites in Temperature Gradient 75 1.5.2 Counter-Balance by a Gradient in the Number Density of Nuclei 78 References 79 2 Kinetics and Structure Formation in Unloaded Quiescent Melts 82 2.1 Introductory Remarks 82 2.2 Empirical Techniques 82 2.2.1 Number Density of Nuclei 82 2.2.2 Growth Speeds of Spherulites 90 2.2.2.1 Growth Speeds of Fast Growing Spherulites 91 2.2.2.2 Growth Speed and Small Angle Light Scattering 101 2.3 Theoretical Considerations 103 2.3.1 Theory of the Growth Speed of Spherulites 103 2.3.2 On the Nature of Primary Nuclei in Polymer Melts 107 2.3.2.1 Some Comments on the Theory by Hoffman and Lauritzen 107 2.3.2.2 The Theory by Larson and Garside 108 2.3.2.3 The Role of Local Alignments 111 2.3.3 Winter’s Gel Point 116 References 118 3 Flow Induced Processes Causing Oriented Crystallization 121 3.1 Preamble 121 3.2 Some Comments of Considerable Reach 122 3.3 Survey of Activities in the Field of Flow Induced Crystallization 129 3.3.1 Duct Flow Experiments 130 3.3.1.1 Short Term Shearing (“Step Strain”) Experiments [17] 130 3.3.1.2 A Preliminary Interpretation of the Results of Section 3.3.1.1 134 3.3.1.3 Optical and Electron Microscopy [17] 137 3.3.1.4 More About Structures and a Growth Mechanism 140 3.3.2 Flow Induced Small-Sized (“Point-Like”) Nuclei 149 3.3.2.1 Rectilinear Shearing Between Glass-Slides 149 3.3.2.2 Influence of Extensional Flow on the Number Density of Nuclei 155 3.3.2.3 Results Obtained with a Peroxide Degraded Polypropylene 158 3.3.2.4 A Conspicuous New Insight 161 3.3.3 Relaxation Phenomena 163 3.3.3.1 A Historical Review 163 3.3.3.2 Other Ways of Observing the Relaxation of Precursors 170 3.3.4 Uninterrupted Flow Treatment 181 3.3.4.1 Continuous Shearing 181 3.3.4.2 Continuous Stretching 187 3.3.4.3 A Preliminary Discussion 191 3.3.4.4 Unlimited Shear as a Source of Information 193 3.3.5 Adherence to the Growth Mechanism 199 3.3.5.1 Transformation of Dormant Nuclei by the Action of Flow [11] 199 3.3.5.2 A Continued Discussion 201 References 205 4 Closing Remarks 210 4.1 Quiescent Melts 210 4.2 Views on Flow Induced Processes 214 4.3 Final Résumé 226 References 228 Author Index 232 Subject Index 236 Front Matter ....Pages i-xiii Required Basic Achievements (Hermann Janeschitz-Kriegl)....Pages 1-69 Kinetics and Structure Formation in Unloaded Quiescent Melts (Hermann Janeschitz-Kriegl)....Pages 71-109 Flow Induced Processes Causing Oriented Crystallization (Hermann Janeschitz-Kriegl)....Pages 111-199 Closing Remarks (Hermann Janeschitz-Kriegl)....Pages 201-222 Back Matter ....Pages 223-229