Table of Content 6
Introduction 10
1 Educational Minimum: Manufacture, Structure, and Mechanical Properties of Polyethylene Resins 14
1.1 Classification and Applications of Polyethylene Resins 14
1.2 Catalysts for Synthesis of Polyethylene Resins 17
1.3 Industrial Processes for the Manufacture of Polyethylene Resins 19
1.4 Chemistry of Ethylene Polymerization Reactions 21
1.5 Molecular Weight Distribution of Polymers and Methods of its Analysis 24
1.6 Examples of Molecular Weight Distribution of Polyethylene Resins 27
1.7 Copolymer Statistics and its Application to Description of LLDPE and VLDPE Resins 33
1.8 Compositional Uniformity of Commercial Polyethylene Resins 35
1.9 Morphology of Polyethylene Resins 39
1.10 Mechanical Deformation of Polyethylene Resins 42
References 44
2 Melt Index and Melt Flow Ratio of Polyethylene Resin 48
2.1 Introduction 48
2.2 Basics of Polymer Rheology Melt Flow Through a Capillary50
2.2.1 Flow of Polymer Melt Through a Cylindrical Capillary 52
2.2.2 Melt Index of Newtonian Liquid 53
2.3 Melt Flow of Monodisperse Polyethylene Resins 54
2.4 Additivity Rules for Viscosity Calculation of Melt Indexes and Melt Flow Ratios from Molecular Weight Distribution Data56
2.4.1 Additivity Rules for Zero-Shear Viscosity .0 56
2.4.2 Additivity Rules for Effective Viscosity and General Expressions for Flow of Non-Newtonian Multi-Component Melt 57
2.5 Examples of Melt Flow Rates and Melt Flow Ratios for Polyethylene Resins of Different Types 61
2.5.1 LLDPE Resins Produced with Supported Ziegler-Natta Catalysts 61
2.5.2 HDPE Resins with Broad Molecular Weight Distributions 64
2.5.3 Effect of Long-Chain Branching 66
References 67
3 Melting Point of Polyethylene Resin 70
3.1 Introduction 70
3.2 Melting Point of HDPE Resin 71
3.3 DSC Melting Curves and Melting Points of LLDPE and VLDPE Resins Produced with Single-Site Catalysts 74
3.3.1 Crystallization Process of Compositionally Uniform Ethylene/a-Olefin Copolymers 77
3.3.2 Model for Secondary Crystallization 78
3.3.3 Combined DSC Model for LLDPE and VLDPE Resins 79
3.4 DSC Melting Curves and Melting Points of LLDPE Resins Produced with Multi-Site Ziegler-Natta Catalysts 81
References 84
4 Crystallinity Degree and Density of Polyethylene Resins 86
4.1 Crystallinity Degree 86
4.1.1 Measurement Methods 86
4.1.2 Definition of Crystallinity Degree of LLDPE and VLDPE Resins Based on Copolymer Statistics 88
4.2 Density 89
4.2.1 Measurement Methods 90
4.2.2 Physical Meaning of Polyethylene Density 90
References 93
5 End-Use Mechanical Properties of Polyethylene Film 96
5.1 Mechanical Properties of Polyethylene Resins 96
5.1.1 Effect of Testing Speed on Mechanical Properties 97
5.1.2Orientation in Polyethylene Film 98
5.2 Dart Impact Strength of LLDPE Film 100
5.2.1 Description of Dart Impact Test 100
5.2.2 Model of Dart Impact Test 102
5.2.2.1 Effects of Mechanical Properties of Resins 105
5.2.2.2 Comparison of Film Made from Ethylene/Butene and Ethylene/Hexene Copolymers 106
5.2.2.3 Effect of Copolymer Composition 107
5.2.2.4 Compositionally Uniform and Compositionally Nonuniform Resins 108
5.3 Tear Strength of LLDPE and LDPE Film 110
5.3.1 Description of Tear Test 110
5.3.2Physical Details of Tear Test 110
5.3.3Model of Tear Test 115
5.3.3.1 Effect of Pendulum Speed 120
5.3.3.2 Effects of Mechanical Properties of Resins 120
5.3.3.3 Effect of Film Orientation 121
5.3.3.4 Comparison of Tear Strength of Ethylene/Butene and Ethylene/Hexene Copolymers 123
5.3.3.5Low Density Polyethylene 123
5.4 Comparison of Factors Determining Results of Tear Test and Dart Impact Test of LLDPE Film 124
References 125
6 End-Use Testing of High Molecular Weight HDPE and MDPE Resins 128
6.1 Top Load Test of HDPE Containers 128
6.1.1 Mechanics of Top Load Test 129
6.2 Dynamic Burst Test of HDPE Tubing and Pipes 131
6.3 Static Burst Test and Long-Term Fatigue in Polyethylene 132
6.3.1 Principal Equation for Low-Stress Failure 133
6.3.2 Physical Mechanism of Polymer Failure under Low Stress 135
6.4 Environmental Stress-Cracking Resistance 138
6.4.1 Description of ESCR Test 138
6.4.2 Physics of Environmental Stress Cracking 139
6.4.3 Structural Parameters of HDPE Resins Affecting ESCR 140
6.4.4 Relationship between ESCR and Long-Term Fatigue in Polyethylene 143
6.4.5 Mechanism of Environmental Stress Cracking 145
References 148
Index 152