Polymer Nanocomposites (eBook)

Xingyi Huang is an Associate Professor at the Shanghai Jian Tong University, China. Chunyi Zhi is an Assistant Professor at the City University of Hong Kong, China.

Preface 6
Contents 8
Part I: Electrical Properties of Polymer Nanocomposites Under Low Electric Field 10
Chapter 1: Dielectric Constant of Polymer Composites and the Routes to High-k or Low-k Nanocomposite Materials 11
1.1 Introduction 11
1.2 Dielectric Polarization in Polymer Composite Materials 12
1.3 High-k Polymer Composite Materials 14
1.3.1 High-k Ceramic Nanoparticle–Polymer Composites 15
1.3.2 High-k Conducting Nanoparticle–Polymer Composites 21
1.4 Low-k Polymer Nanocomposite Materials 25
1.4.1 Low-k Hollow Particle/Polymer Nanocomposite Materials 27
1.4.2 Low-k Hybrid Particle/Polymer Nanocomposite Materials 29
1.5 Conclusions 30
References 31
Chapter 2: Dielectric Loss of Polymer Nanocomposites and How to Keep the Dielectric Loss Low 37
2.1 Introduction 37
2.2 The Origin of Dielectric Loss 38
2.2.1 Losses from Molecular Polarization 39
2.2.1.1 Strategies for Loss Reduction 41
2.2.2 Losses from Charge Carrier Propagation 42
2.2.2.1 Strategies for Loss Reduction 44
Improving Filler Dispersion by Surface Modification 45
Grafted with Short Organic Ligands 45
Grafted with Long Polymer Brushes 47
The Influence of the Interfacial Region 48
Fabricating Special Nanostructures 49
Core–Shell Structure 49
Core–Double-Shell Structure 50
Core–Satellite Structure 51
Bimodal System 53
2.3 Concluding Remarks 55
References 55
Chapter 3: Electrical Conductivity and Percolation Behavior of Polymer Nanocomposites 59
3.1 Introduction 59
3.2 Percolation Theory 61
3.2.1 The Basics 61
3.2.2 Excluded Volume Theory of Percolation 62
3.2.2.1 Widthless Stick 63
3.2.2.2 A Stick with a Finite Width 63
3.2.2.3 A Three-Dimensional Stick (Capped Cylinder) 64
3.3 Factors of Affecting Percolation Threshold and Electrical Conductivity of Polymer Nanocomposites 68
3.3.1 Filler Size, Shape, and Aspect Ratio 68
3.3.2 Dispersion State of Fillers 71
3.3.2.1 Methods to Disperse Fillers in Polymer 72
Solution Mixing 72
Melt Processing 73
In Situ Polymerization 73
Covalent Functionalization 75
Non-covalent Functionalization 75
3.3.2.2 Effects of Dispersion State of Fillers on Electrical Properties of Polymer Nanocomposites 77
3.3.3 Orientation of Fillers 78
3.3.4 Matrix Properties 80
3.4 Lightweight Carbon Material–Polymer Nanocomposite Foams with Excellent Conductivity 81
3.5 Conclusion 83
3.5.1 Aspect Ratio of Fillers 83
3.5.2 Dispersion State of Fillers 84
3.5.3 Orientation of Fillers 84
3.5.4 Characteristics of Matrix 84
References 85
Chapter 4: Positive Temperature Coefficient Effect of Polymer Nanocomposites 91
4.1 Introduction 91
4.2 Conduction Mechanism of CPC 92
4.3 Theoretical and Phenomenological Background of PTC Effect 93
4.3.1 Conducting Chain and Thermal Expansion Theory 93
4.3.2 Tunneling Current Mechanism 93
4.3.3 Mechanism of Congregation and Migration Changes of Filler Particles 94
4.3.4 Electrical Field Emission Mechanism 94
4.3.5 Internal Stress Mechanism 95
4.3.6 The Percolation Theory and PTC Effect 95
4.4 Influence of Polymer Matrix on PTC Effect of Nanocomposites 96
4.4.1 Influence of Polymer Crystallinity on PTC Effect 96
4.4.2 Influence of Melting Temperature of Polymer on PTC Critical Temperature 97
4.4.3 Influence of Binary-Polymer Blends on Percolation Threshold 98
4.5 Influence of Conductive Filler on PTC Effect of Nanocomposites 101
4.5.1 The Kinds of Conductive Filler 101
4.5.1.1 Carbon System Filler 101
4.5.1.2 Metal or Metal Ceramic System Filler 103
4.5.1.3 Morphological Control Through a Mixed Filler 106
4.5.2 The Grain Size and Morphology of Conductive Filler 107
4.5.2.1 Effect of Filler Size 108
4.5.2.2 Effect of Filler Shape 110
4.5.2.3 Effect of Filler Distribution 110
4.6 The Effective Ways to Improve the PTC Properties of Nanocomposites 111
4.6.1 Surface Modification of Conductive Filler 111
4.6.2 The Cross-Linked Polymer Nanocomposites 113
4.6.3 Heat Treatment of the Nanocomposite 113
4.7 Conclusions 115
References 116
Part II: Electrical Properties of Polymer Nanocomposites Under High Electric Field 119
Chapter 5: Dielectric Breakdown in Polymer Nanocomposites 120
5.1 Introduction 120
5.2 Theories of Dielectric Breakdown 120
5.2.1 Intrinsic Breakdown 121
5.2.2 Electron Avalanche Breakdown 122
5.2.3 Thermal Breakdown (Impulse and Steady State) (Fig. 5.3) 123
5.2.4 Electromechanical Breakdown 125
5.3 Treeing Breakdown Phenomena 125
5.3.1 Electrical Trees Electrode Systems for Performance Evaluation 125
5.3.2 Three Possible Processes in Incubation Period 127
5.3.3 Charge Injection and Extraction in Tree Incubation Period 129
5.3.4 Processes from Tree Initiation to Growth 130
5.4 Short-Time Dielectric Breakdown of Nanocomposites 131
5.5 Long-Term Breakdown Characteristics of Nanocomposites 133
5.5.1 V-t Characteristics 133
5.5.2 Derivation of Tree Growth Speed 134
5.5.3 S-V Characteristics 135
5.5.4 Explanation of Cross Points X1, X2, X3, X4, and X5 136
5.5.5 Consideration of X3 and X4 139
5.5.6 Initial Tree Length and Tree Buds 139
5.5.7 Suppression of Treeing by Nanofillers 140
5.5.8 Roles of Nanofillers in Tree Growth Processes 142
References 143
Chapter 6: Polymer Nanocomposites for Power Energy Storage 145
6.1 Introduction 145
6.2 Increasing Dielectric Constant of Polymer Nanocomposites 147
6.2.1 Using Ceramics as Fillers 147
6.2.1.1 Surface Functionalization of Filler Particles 147
6.2.1.2 High Aspect Ratio Fillers 151
6.2.1.3 Nanofillers with Moderate Dielectric Constant 153
6.2.2 Percolative Polymer Nanocomposites 156
6.2.2.1 Giant Dielectric Constants of Percolative Nanocomposites 156
6.2.2.2 Conductive Fillers Covered with Insulation Layer 157
6.3 Increasing Breakdown Strength of Polymer Nanocomposites 158
6.3.1 Polymer Nanocomposites with Insulating Nanoparticles 158
6.3.2 Incorporation of Insulating Nanolamilates 160
6.4 Simultaneous Improvements of Dielectric Constant and Breakdown Strength 161
6.5 Conclusions 163
References 164
Part III: Thermal Properties of Polymer Nanocomposites 170
Chapter 7: Thermal Stability and Degradation of Polymer Nanocomposites 171
7.1 Introduction 171
7.2 Types of Nanofillers 172
7.2.1 Nano-oxides 172
7.2.2 Carbon Nanotubes 172
7.2.3 Nanoclays 173
7.2.4 Other Nanofillers 174
7.3 Synthesis of Polymer Nanocomposites 175
7.4 Degradation Process of Polymer Matrices 176
7.5 Thermal Stability of Polymer Nanocomposites 178
7.5.1 Polymer/Nano-oxide Nanocomposites 178
7.5.2 Polymer/Carbon Nanotube Nanocomposites 179
7.5.3 Polymer/Clay Nanocomposites 180
7.5.4 Polymers Reinforced with Other Types of Fillers 183
7.6 Synergy Between Stabilizers and Nanofillers 184
7.7 Conclusions and Perspectives 185
References 187
Chapter 8: Thermomechanical Analysis of Polymer Nanocomposites 195
8.1 Introduction 195
8.2 Polymer Nanocomposites Containing Nanoplatelets 197
8.2.1 Clay-Based Polymer Nanocomposites 198
8.2.2 Graphene or Graphite-Based Polymer Nanocomposites 218
8.3 Polymer Nanocomposites Containing Nanospheres 221
8.3.1 Silica-Based Polymer Nanocomposites 221
8.3.2 POSS-Based Polymer Nanocomposites 226
8.4 Polymer Nanocomposites Containing Nanocylinders 230
8.4.1 Carbon Nanotube-Based Polymer Nanocomposites 231
8.4.2 Carbon Nanofiber-Based Polymer Nanocomposites 235
8.5 Conclusions 237
References 238
Chapter 9: Applications of Calorimetry on Polymer Nanocomposites 247
9.1 Introduction 247
9.2 Discussion 250
9.3 Conclusion 257
References 257
Chapter 10: Electrically Conductive Polymer Nanocomposites with High Thermal Conductivity 259
10.1 Introduction 259
10.1.1 The Utility of Carbon Nanotubes and One-Dimensional Fillers 260
10.2 Experimental Methodology: Nanocomposite Synthesis and Characterization 262
10.2.1 Synthesis 262
10.2.2 Characterization 264
10.3 Experimental Observations 268
10.3.1 Electrical Conductivity Measurements 268
10.4 Modeling of Electrical and Thermal Effects in Polymeric Nanocomposites 270
10.4.1 The Nanotube–Polymer Interface 270
10.4.2 Rationale for the Percolation Behavior in Thermal Conductivity 271
10.4.3 Effect of Nonlinear Filler Geometry: Does a Change of Morphology Imply Enhanced Electrical and Electromagnetic Characteristics? 274
10.4.3.1 Synthesis of CCNTs and CCNT-Based Polymer Nanocomposites 275
10.4.3.2 DC Conductivity Measurements 276
10.4.3.3 Dielectric Constant Measurements 276
10.4.3.4 AC Conductivity Measurements (Beyond Percolation Theory?) 277
10.4.3.5 Electromagnetic Shielding Efficiency 279
10.5 Conclusions 280
References 281
Chapter 11: Thermally Conductive Electrically Insulating Polymer Nanocomposites 285
11.1 Introduction 285
11.1.1 High Thermal Conductive Polymer Composite Materials 285
11.1.2 Overview of Thermally Conductive Electrically Insulating Polymer Composites 286
11.1.3 Theory of Heat Conduction in Electrically Insulating Solid-State Materials 287
11.2 High Thermal Conductivity Inorganic Fillers 287
11.2.1 Oxides 288
11.2.1.1 Alumina (Al2O3) 288
11.2.1.2 Silica (SiO2) 290
11.2.1.3 Zinc Oxide (ZnO) 292
11.2.2 Nitrides 293
11.2.2.1 Aluminum Nitride (AlN) 293
11.2.2.2 Boron Nitride (BN) 295
11.2.2.3 Silicon Nitride (Si3N4) 296
11.2.3 Graphene Oxide (GO) 297
11.2.4 Silicon Carbide (SiC) 299
11.3 High Thermal Conductive Electrically Insulating Polymer Composites 300
11.3.1 Oxides as Fillers 300
11.3.1.1 Al2O3 300
11.3.1.2 SiO2 301
11.3.1.3 ZnO 302
11.3.2 Nitride as Fillers 304
11.3.2.1 AlN 304
11.3.2.2 BN 306
11.3.2.3 Si3N4 308
11.3.3 Graphene Oxide as Fillers 309
11.3.4 SiC as Fillers 310
11.4 Essential Factors to Achieve High Thermal Conductivity 311
11.4.1 Nature of Polymer and Thermal Conductivity of Fillers 311
11.4.2 Filler Size and Shape 313
11.4.3 Surface Modification 313
11.4.4 Synergistic Effect 316
11.4.5 Orientation of Fillers 317
11.5 Summaries and Future Prospects 318
References 319
Chapter 12: Polymer–Clay Nanocomposites: A Novel Way to Enhance Flame Retardation of Plastics and Applications in Wire and Cable Industry 326
12.1 Introduction 326
12.2 Bentonite Clay Surface Chemistry 327
12.3 Nanocomposite Formation and Structure 330
12.4 Flame Retardation of Polymer–Clay Nanocomposites 334
12.5 Synergy of Nanocomposite with Traditional Flame Retardant 338
12.6 New Development and Outlook 346
References 349
Index 350