Photochemical Behavior of Multicomponent Polymeric-based Materials (eBook)

Contents 6
About the Editors 8
1 Theoretical Aspects Regarding Polymer Photochemistry 10
Abstract 10
1 Introduction 10
2 Theoretical Aspects Regarding Polymer Photochemistry 11
2.1 General Photodegradation Mechanisms of Polymers 16
2.1.1 Photo-Oxidative Mechanism 16
2.1.2 Initiation 16
2.1.3 Propagation 17
2.1.4 Other Aspects Concerning Hydroperoxides Photodecomposition 19
2.1.5 The Energy Transfer Between Carbonyl Groups and Hydroperoxide Structures 20
2.1.6 The Photo-Fries Rearrangement 21
2.1.7 Termination 24
3 Conclusions 27
References 28
2 Factors Influencing the Photochemical Behavior of Multicomponent Polymeric Materials 30
Abstract 30
1 Introduction 32
2 Influence of Chemical Structure 34
3 Presence of Impurities 42
4 Influence of Wavelength and Irradiation Dose 47
5 Influence of Temperature 54
6 Influence of Humidity 58
7 Conclusions 64
References 64
3 Multicomponent Polymer Materials: Photodegradation Mechanism 75
Abstract 75
1 Introduction 75
2 Photodegradation Mechanisms of Multifunctional Polymeric Materials 77
3 Conclusions 95
References 95
4 Photochemical Behavior of Wood Based Materials 98
Abstract 98
1 Introduction 98
2 Photochemical Behaviour of Wood Based Materials 101
3 Conclusions 108
References 109
5 Photochemical Behavior of Synthetic Polymeric Multicomponent Materials Composites and Nanocomposites 115
Abstract 115
1 Introduction 117
2 Photochemical Behavior of Thermoplastic Matrix Based Composites 119
2.1 General Considerations 119
2.2 Photochemical Behavior of Thermoplastic Matrices 120
2.3 Thermoplastic Composites with Natural Fillers from Renewable Resources 122
2.3.1 Wood Particles (Chips and Flour) 122
2.3.2 Wood Fibers and Other Ligno-cellulosic Fibers 125
2.3.3 Natural Protein Fibers (Silk, Wool) 127
2.4 Thermoplastic Composites with Inorganic and Synthetic Fillers 128
2.4.1 Inorganic Particulate Fillers 128
2.4.2 Synthetic Fibers Reinforced Thermoplastics 131
3 Thermoplastic Nanocomposites 132
3.1 Polyolefins-Based Nanocomposites 133
3.2 Other Thermoplastics Used in Nanocomposites 135
3.3 Nanocomposite UV-Protective Coatings 136
4 Photochemical Behavior of Thermosetting Matrix Based Composites 139
4.1 UV-Cured Thermosetting Matrix Based Composites 140
4.1.1 Fiber-Reinforced Epoxy Resins 140
4.1.2 Glass Fiber-Reinforced Polyester Resins 142
4.1.3 Dual Cure Processing 144
4.2 UV-Initiated Degradation of Thermosetting Polymers Based Composites 144
4.2.1 Particle-Filled Epoxy Resins 145
4.2.2 Glass/Graphite Fibers Reinforced Epoxy Resins 145
4.2.3 Other Thermosetting Resins-Based Composites 147
5 Photochemical Behavior of Thermosetting Matrix Based Nanocomposites 147
5.1 Clay-Thermosetting Polymer Nanocomposites 148
5.2 Thermosetting Polymer–Silica Nanocomposites 149
5.3 CNTs-Epoxy Resins Nanocomposites 151
5.4 Graphene Platelets–Thermosetting Polymer Nanocomposites 152
5.5 Organic–Inorganic Hybrid Materials Obtained by the Dual Cure Process 152
5.5.1 Epoxy-Based Hybrid Materials 153
5.5.2 Acrylate-Based Hybrid Materials 153
5.5.3 Other Thermosetting Matrices Used for Hybrid Materials 154
6 Concluding Remarks and Future Developments 155
References 156
6 Stabilization of Polymers Against Photodegradation 171
1 Introduction 171
2 Mechanisms of Polymer Photodegradation 172
3 Photostabilization 176
3.1 Screening of UV Radiation 176
3.2 Quenchers of the Excited States 179
3.3 Hydroperoxides Decomposers 180
3.4 Radical Scavengers 180
3.4.1 Hindered amine (hindered amine light stabilizers, HALS) 180
4 Stabilization Characterization of Various Polymers 185
4.1 Polyethylene 185
4.2 Polypropylene 188
4.3 Other Polymers 191
5 Conclusions 193
References 194
7 Weathering Degradation of Polymers 199
1 General Considerations 199
2 Weathering of Engineering Polymers 210
2.1 Polyethylene 210
2.2 Polypropylene 213
2.3 Ethylene–Polypropylene Elastomers 218
2.4 Other Polymers 222
3 Conclusion 225
References 226
8 Life-Time Prediction of Multicomponent Polymeric Materials 232
Abstract 232
1 Methods of Life-Time Prediction of Multicomponent Polymeric Materials 232
2 Accelerated and Natural Aging of Multicomponent Polymeric Materials 236
2.1 The Reciprocity Law 256
2.2 Effect of Temperature on Photochemical Accelerated Aging 256
3 Conclusions 259
References 259
9 Photochemical and Photophysical Behavior of Azopolymer Compounds 264
1 Introduction 264
2 Photochemical Behaviors of Azopolymers 265
2.1 Spectroscopic Properties of Azobenzenes 266
2.2 Photoisomerization Process 270
2.3 Isomerization Mechanism 272
2.4 Application of Photoisomerization Process in Drug Delivery Systems 273
3 Photophysical Behaviors of Azopolymers 276
3.1 Anisotropy 279
3.2 Birefringence 280
3.3 Types of Motions in Azobenzenes 283
3.4 Surface Relief Grating (SRG) 285
3.5 Nonlinear Behavior of Azo Compounds 290
4 Conclusion 291
References 291
10 Photochemical Process of Wood-Thermoplastic Composites 295
1 A Brief Introduction of WPCs 295
1.1 Definition of WPCs 295
1.2 Significance of WPCs 296
1.3 Development History of WPCs 297
1.4 Application of WPCs 298
2 Composition and Manufacturing of WPCs 299
2.1 Wood Materials 299
2.1.1 Physical Characterization 299
2.1.2 Chemical Composition 300
2.2 Thermoplastic Matrix Materials 302
2.2.1 Polyethylene (PE) 302
2.2.2 Polypropylene (PP) 303
2.2.3 Polyvinyl Chloride (PVC) 304
2.3 Additives 305
2.3.1 Coupling Agents 305
2.3.2 Light Stabilizer 307
2.3.3 Antioxidants 308
2.3.4 Other Additives 308
2.4 Manufacturing Process 309
2.4.1 Extrusion 309
2.4.2 Injection Molding 309
2.4.3 Compression Molding 309
3 Photodegradation and Mechanism of WPCs 310
3.1 Testing Methods 310
3.1.1 Weathering Parameters 310
3.1.2 Weathering Methods 311
3.1.3 Physical and Mechanical Properties Tests 312
3.1.4 Characterizations 315
3.2 Surface and Mechanical Properties Influenced by Photodegradation 316
3.2.1 Surface Color Change 317
3.2.2 Surface Morphology 318
3.2.3 Mechanical Properties 318
3.3 Photodegradation Mechanism of Thermoplastics 320
3.3.1 Photodegradation Mechanism of Polyethylene (PE) 320
3.3.2 Photodegradation Mechanism of Polypropylene (PP) 322
3.3.3 Photodegradation Mechanism of Polyvinyl Chloride (PVC) 324
3.4 Photodegradation Mechanism of Wood 324
3.4.1 Depth of Photodegradation 325
3.4.2 Photodegradation Mechanism of Lignin 325
3.4.3 Photodegradation Mechanism of Holocellulose 328
3.4.4 Photodegradation Mechanism of Extractives 330
3.5 Photodegradation Mechanism of WPCs 330
4 Methods to Retard Photodegradation of WPCs 332
4.1 Additives 332
4.1.1 Colorants 332
4.1.2 Photostabilizers 333
4.1.3 Antioxidants 334
4.1.4 Nanoclays 338
4.2 Coating and Chemical Modification 339
4.2.1 Surface Painting 339
4.2.2 Chemical Modification 340
4.3 Changing Wood Fiber Composition 341
5 Summary 343
References 344
11 Photochemical Behavior and Optoelectronic Applications of Some Conjugated Polymers 351
Abstract 351
1 Introduction 351
2 Fabrication of Polymer Light Emitting Diode (PLEDs) Based on Conjugated Polymers 352
3 Synthesis of Conjugated Polymers 353
3.1 Dehydrohalogenation Reactions 354
3.2 Precursor Route Polymerization 355
3.3 Transition Metal Catalyzed Coupling Reactions 355
3.3.1 Kumada Coupling Reaction 356
3.3.2 McCullough Coupling Reaction 356
3.3.3 Suzuki Coupling Reaction 356
3.3.4 Heck Coupling 356
3.4 Condensation Polymerizations 357
3.4.1 Wittig Reaction 357
3.4.2 Knoevenagel Condensation Polymerization 358
3.4.3 Horner-Emmons Condensation Polymerization 358
4 Common Conjugated Polymers Used in PLEDs 359
4.1 Polyfluorene and Its Derivatives 359
4.2 Polyphenylene (PPP) and Its Derivatives 360
4.3 Poly(Phenylene Vinylene) (PPV) and Its Derivatives 361
4.4 Polythiophene and Its Derivatives 363
5 Fabrication of Solar Cells Using Conjugated Polymers 364
6 Conjugated Polymers Used in Organic Solar Cells 367
6.1 Phenylene-Vinylenes and Its Derivatives 367
6.2 Poly(3-Alkylthiophenes) and Its Derivatives 368
6.3 Polypyrrole and its Derivatives 371
6.4 Porphyrin Based Polymers 371
6.5 Poly(Carbazole) and Its Derivatives 372
7 Conclusion and Future Prospects 373
Acknowledgment 373
References 373
12 Optical Performance of Organic Distributed Feedback Lasers Based on Holographic Polymer Dispersed Liquid Crystals 382
1 Introduction 382
2 Holographic Polymer Dispersed Liquid Crystals 383
2.1 Materials for HPDLCs 383
2.2 Writing Setups for HPDLCs 385
2.3 HPDLC Morphologies 385
3 HPDLCs for Organic DFB Lasers 388
3.1 Optical Pumping for Opto-Optical HPDLC DFB Lasers 388
3.2 HPDLC as Light Feedbacks 389
3.2.1 HPDLC as DFB Laser Cavities 389
3.2.2 Methods to Improve Optical Performance (HPDLC as DFB Laser Cavities) 390
3.2.3 HPDLCs as External Feedbacks 391
3.2.4 Method to Improve Optical Performance (HPDLC as External Feedbacks) 393
4 HPDLCs for Novel DFB Laser Applications 395
4.1 HPDLCs for Multi-Wavelength DFB Lasers 395
4.2 Tunable HPDLC Lasing Behaviors 397
4.2.1 Thermo-Tuning 397
4.2.2 Electro-Tuning 399
4.2.3 Photo-Tuning 399
5 Conclusions 401
References 402