Dielectric Polymer Nanocomposites (eBook)

Dielectric Polymer Nanocomposites 
1 
1 Background, Principles and Promise of Nanodielectrics 10
1.1 An Introductory Perspective of Electrical Insulation 10
1.1.1 The Emergence of Nanocomposites 11
1.1.2 Multifunctionality 12
1.1.3 A Philosophical Perspective 13
1.2 The Compounding of Dielectric Nanocomposites 16
1.2.1 The Importance and Assessment of Dispersion 17
1.2.2 Functionalization 20
1.3 Property Modifications 23
1.3.1 Property Augmentation of Practical Significance 23
1.3.2 Property Characterization for Diagnostic Purposes 27
1.3.2.1 Dielectric Spectroscopy 28
1.3.2.2 Internal Space Charge Characteristics 30
1.3.2.3 Dielectric Absorption 30
1.3.2.4 Thermally Stimulated Currents 33
1.3.2.5 Electroluminescence 34
1.4 Other Issues 35
References 36
2 The Processing of Nanocomposites 40
2.1 Introduction to Nanofillers 40
2.1.1 Classification of the Fillers 40
2.1.2 Surface Filler Treatment 45
2.2 Classification of the Processing of Nanocomposites 49
2.2.1 In Situ Polymerization Process 49
2.2.1.1 Thermoplastic Materials 50
2.2.1.2 Thermosetting Materials 51
2.2.2 Solvent Method 53
2.2.3 Melt Blending 54
2.2.4 Sol--Gel Process 56
2.3 Effects of Contaminants 57
2.3.1 Effect of By-Products of a Compatibilization Process 57
2.3.2 Effect of Moisture 61
2.4 The Assessment of Dispersion and Morphological Characterization 67
References 69
3 Special Considerations for Clay-Based Materials 74
3.1 The Nature of Clay Composites 74
3.1.1 Structure and Properties of Clay 74
3.1.2 Characteristics of Clay Nanocomposites 75
3.1.3 Effects of Clay Dispersion on Polymer Properties 76
3.1.3.1 Mechanical Properties 77
3.1.3.2 Thermal Properties 77
3.1.3.3 Electrical Insulation (Partial Discharge Resistance) 78
3.1.3.4 Electrical Insulation (Insulation Breakdown Time) 79
3.1.3.5 Gas Barrier 80
3.1.3.6 Flame Resistance 80
3.2 Intercalation and Exfoliation 82
3.2.1 Preparation Methods of Clay Nanocomposites 82
3.2.2 Improved Methods for Manufacturing Epoxy-Based Clay Nanocomposites 84
3.3 Chemical Treatments and Organic Modification 85
3.3.1 Organic Modifier of Clays and Modification Method 86
3.3.2 Confirming Organic Modification of Clays 89
3.3.3 Factors in the Intercalation Process 91
3.4 Compounding of Layered Silicate Nanocomposites 91
3.4.1 Factors in the Exfoliation Process 92
3.4.2 Rheological Characteristics of Polymer Containing Clays 95
3.4.3 Manufacture of Nanocomposite Using Unmodified Clays 97
3.5 In Situ Polymerization 97
3.5.1 Manufacture and Properties of Polyamide-Based Clay Nanocomposite 98
3.5.2 Manufacture and Properties of Epoxy-Based Clay Nanocomposite 99
3.6 Summary 100
References 101
4 The Chemistry and Physics of the Interface Regionand Functionalization 103
4.1 Introduction 103
4.1.1 Characterization 104
4.2 The Physical and Chemical Structure of Polymers 104
4.2.1 Key Physical and Chemical Properties of Polymers Used for Polymer Nanocomposites 104
4.2.2 Comparison of Polymers and Rubbers for Use in Nanocomposites and Their Role in the Interface Region 107
4.3 Morphology, Glass Transition and Free Volume of Polymers 108
4.4 Nanoparticles 109
4.4.1 Spherical Inorganic Particles 109
4.4.2 Colloidal Spherical Particles 111
4.4.3 Intercalated and Exfoliated Nanoparticles 112
4.4.4 Other Nanoparticle Structures 115
4.4.5 Bonding in Nanoparticles 116
4.5 The Surface Chemistry of Nanoparticles and Its Role in Charge Injection and Trapping 117
4.5.1 Functionalization 118
4.6 The Choice and Basis for Coupling Agents 118
4.7 Use of Compatibilizers for Intercalated and Exfoliated Nanocomposites 121
4.8 Morphology, Glass Transition and Free Volume in Polymer Nanocomposites 121
4.9 Interface Chemistry and Physics, Bonding, and Entanglement 124
4.9.1 Chemistry 124
4.9.2 Dielectric Relaxation Measurements 125
4.9.3 Electron Paramagnetic Resonance Measurements 130
4.9.4 Temperature-Modulated DSC Measurements 132
4.9.5 The Gouy-Chapman Layer: Interface Impurity Chemistry 132
4.9.6 Entanglement 133
4.10 Nucleation Effects 134
4.11 The Role of Water in Nanocomposites 134
4.12 Final Remarks 135
References 136
5 Modeling the Physics and Chemistry of Interfacesin Nanodielectrics 140
5.1 Introduction 140
5.2 Ab Initio Modeling Techniques 141
5.3 DFT Modeling of Polymers 144
5.4 Interfacial Electronic Structure 146
5.4.1 Background 146
5.4.2 DFT Determination of Offsets 147
5.4.3 The Layer-Decomposed Density of States 148
5.5 Dielectric Constant Across Interfaces 151
5.5.1 Background 151
5.5.2 Basics of the Theory of the Local Dielectric Permittivity 153
5.5.3 Applications 154
5.6 Electron-Phonon Interactions 158
5.7 Stability of Interfaces 160
5.8 Impurity Segregation at Interfaces 161
5.9 Concluding Thoughts 163
References 164
6 Mechanical and Thermal Properties 169
6.1 Introduction 169
6.2 The Effect on Elastic Modulus and Mechanical Strength 171
6.2.1 Nanofillers and Nanocomposites 171
6.2.2 Tensile Properties 174
6.3 The Effect on Fracture and Impact Toughness 176
6.3.1 Fracture Toughness 176
6.3.1.1 Crack Pinning 178
6.3.1.2 Crack Deflection 180
6.3.1.3 De-bonding and Plastic Void Growth 181
6.3.1.4 Localized Plastic Deformation of Matrix (Shear Banding and Crazing) 182
6.3.1.5 Microcracking and Crack Bridging 183
6.3.2 Impact Toughness 184
6.4 The Effect on Long-Term Behaviors 185
6.4.1 Wear and Abrasion Resistance 185
6.4.1.1 Adhesive Wear 186
6.4.1.2 Abrasive Wear 186
6.4.1.3 Surface Fatigue 186
6.4.1.4 Fretting Wear 187
6.4.2 Fatigue Behavior 189
6.4.3 Creep Behavior 190
6.5 The Effect of Particulate Inclusion on Glass Transition 192
6.6 Thermal Conductivity 196
References 198
7 Electrical Properties 203
7.1 Charge Storage and Transport in Polymers and Nanocomposites 203
7.1.1 Introduction 203
7.1.2 Charge Transport in Insulating Systems 204
7.1.3 Charge Transport in Polymers 205
7.1.4 Electrode Effects 208
7.1.5 Space Charge Effects 209
7.1.6 Effect of Nanoparticles and Interaction Zone on Charge Transport 211
7.1.7 Percolation Effects 213
7.1.8 Examples of Charge Movement in Nanocomposites 216
7.1.9 Internal Charge Distribution in Nanocomposites 218
7.1.10 Concluding Remarks on Charges in Nanocomposites 221
7.2 Dielectric Response 221
7.2.1 Dielectric Spectroscopy 221
7.2.2 Dielectric Response of Nanocomposites 222
7.3 Electrical Breakdown 226
7.3.1 Introduction 226
7.3.2 Polyethylene Nanocomposites 226
7.3.3 Epoxy Nanocomposites 227
7.3.4 PVA Nanocomposite 229
7.3.5 Surface Functionalization of Nanoparticles 229
7.3.6 Voltage Endurance 230
7.4 Concluding Comments 232
References 232
8 Interface Properties and Surface Erosion Resistance 235
8.1 Introduction 235
8.2 Interface Properties of Nanocomposites 236
8.2.1 Silane Couplings 236
8.2.2 Wilkes' Model 236
8.2.3 Interface Models 238
8.2.3.1 Conceptual Illustration of Interfaces 238
8.2.3.2 Bound Polymers 238
8.2.3.3 Evidence for Far-Distance Interaction 239
8.2.3.4 Multi-core Model 241
8.2.3.5 Water Shell Model 243
8.3 Partial Discharge Resistance of Polymer Nanocomposites 243
8.3.1 Evaluation Methods for PD Resistance 243
8.3.2 Polyamide/Layered Silicate Nanocomposites 245
8.3.3 Epoxy Nanocomposites 247
8.3.4 Polyethylene and Polypropylene Nanocomposites 248
8.3.5 Possible Mechanism for PD Erosion 248
8.4 Laser and Plasma Ablation Resistance of Polymer Nanocomposites 250
8.5 Surface Erosion Resistance of Silicone Nanocomposites for Outdoor Use 251
8.6 Treeing Resistance of Polymer Nanocomposites 254
8.6.1 Electrode Systems for Treeing Experiments 254
8.6.2 Treeing Lifetime 255
8.6.3 Possible Effects of Nano-fillers on Treeing 257
8.6.4 Tree Initiation 258
8.7 Mechanisms of Surface Erosion and Tree Propagation in Polymer Nanocomposites 259
8.7.1 Summary for Experimental Verification 259
8.7.2 Consideration of Mechanisms of Erosion due to Partial Discharge and Treeing 259
8.8 Conclusions 262
References 262
9 Non-linear Field Grading Materials and Carbon Nanotube Nanocomposites with Controlled Conductivity 265
9.1 Introduction 265
9.2 Application of Electric Field Grading Materials for High-Voltage Cable Terminations 265
9.3 Shielding Applications for Highly Conductive Composites 267
9.4 Background on Percolation 269
9.5 Non-linear Electrical Nanocomposites for Field Grading Applications 272
9.5.1 Introduction 272
9.5.2 Effect of Particle Size on Composite Resistivity and Onset of Non-linearity 273
9.5.3 Network Model for Non-linear Behavior 275
9.5.4 Character of the Particle/Particle Conductivity 277
9.5.5 Capacitive Field Grading Materials 281
9.6 Carbon Nanotube/Insulating Polymer Composites for High Conductivity Applications 283
9.7 Summary 287
References 287
10 The Emerging Mechanistic Picture 291
10.1 Introduction 291
10.2 Charge Transport in Insulating Polymers 292
10.2.1 Electronic or Ionic Charge Carriers? 292
10.2.2 Electronic Energy Bands 292
10.2.3 Electron Injection, Transport and Trapping 293
10.3 Nanodielectric Models 295
10.3.1 The Interface Model 296
10.3.1.1 Interface Dimensions 296
10.3.1.2 The Tanaka et al. Formulation 298
10.3.1.3 The Lewis Formulation 298
10.3.2 Conductivity, Space Charge and the Interface Model 299
10.4 Conductivity and Space Charge in Selected Nanodielectrics 300
10.4.1 XLPE/Silica 301
10.4.2 LDPE/TiO2 306
10.4.3 LDPE/ZnO 310
10.4.4 LDPE/MgO 312
10.4.5 Poly(Ethylene-Ethyl Acrylate)/Carbon Nanotubes 314
10.4.6 Polystyrene/Carbon Nanofiber Composites 315
10.4.7 Polypropylene/Layered Silicate 318
10.5 Tailoring Charge Transport Properties 321
10.6 Emerging Charge Transport Mechanisms 321
References 322
11 Industrial Applications Perspective of Nanodielectrics 326
11.1 Introduction 326
11.2 Background 327
11.3 Polymer Nanocomposites 328
11.4 The Commercial Impact of Enhanced Electric Strength and Endurance 329
11.5 Opportunities for Enhanced High-Temperature Dielectrics 333
11.6 Cryogenic Applications and Other Extreme Environments 335
11.7 High-Voltage Stress Grading Materials and Conducting Nanocomposites 336
11.8 Applications in the Capacitor Industry 336
11.9 Multi-functional Opportunities 338
11.10 Conclusions 339
References 339
A Diagnostic Methods for Mechanistic Studies in Polymer Nanocomposites 344
A.1 Dielectric Spectroscopy 344
A.2 Pulsed Electroacoustic Analysis 346
A.2.1 Experimental Details 348
A.2.2 Signal Processing and Calibration 349
A.3 Thermally Stimulated Currents 351
A.3.1 Methodology 351
A.4 Electron Paramagnetic Resonance 353
A.4.1 Experimental Method 353
A.4.2 Interpretation 354
A.5 Dielectric Absorption 355
A.6 Spectrally-Resolved Electroluminescence 356
A.6.1 Experimental Details 357
A.7 Infrared Spectroscopy 358
A.7.1 Sample Preparation and Measurement 359
A.7.2 Interpretation 359
A.8 Differential Scanning Calorimetry 361
A.9 Electric Strength, Voltage Endurance, and Partial Discharge Measurements 362
A.9.1 The Stochastic Nature of Electrical Failure 363
A.9.2 Electric Strength 363
A.9.3 Voltage Endurance 364
A.9.4 Partial Discharge Measurements 365
Index 368