Oxydative Ageing of Polymers

This book aims to rehabilitate kinetic modeling in the domain of polymer ageing, where it has been almost abandoned by the research community. Kinetic modeling is a key step for lifetime prediction, a crucial problem in many industrial domains in which needs cannot be satisfied by the common empirical methods. The book proposes a renewed approach of lifetime prediction in polymer oxidative ageing. This approach is based on kinetic models built from relatively simple mechanistic schemes but integrating physical processes (oxygen diffusion and stabilizer transport), and use property (for instance mechanical failure) changes. An important chapter is dedicated to radiation-induced oxidation and its most important applications: radiochemical ageing at low dose rates and photo-chemical ageing under solar radiation. There is also a chapter devoted to the problem of ageing under coupled oxidation and mechanical loading.

Autorentext

Jacques Verdu obtained the Docteur d'Etat at University of Pierre and Marie Curie (Paris) in 1976 and became Professor at Ecole Nationale Supérieure d'Arts et Métiers in 1981. In 1980 he created a research laboratory, Laboratoire de Transformation et Vieillissement des polymers (LTVP), of which he was the director until 2008 at which point he became Professor Emeritus. He has published about 280 papers in scientific journals, mostly on polymer ageing, with others on polymer physics, mainly network properties, and has co-authored about a dozen of books and about 400 conferences. He has obtained 3 scientific awards and 2 honorary medals.

Inhalt
Acknowledgements xi

General Introduction xiii

Chapter 1. Methodological Aspects 1

1.1. Definitions 1

1.2. Empirical and semi-empirical models 4

1.3. Towards a non-empirical method of lifetime prediction 8

1.4. Arguments against kinetic modeling 11

1.5. Principles of model elaboration 15

Chapter 2. Aspects Common to all Oxidation Processes
17

2.1. Oxidation: a radical chain mechanism 17

2.2. Propagation 20

2.3. Termination 25

2.4. Initiation 30

2.5. Thermodynamic aspects 41

Chapter 3. Basic Kinetic Schemes 45

3.1. Simplifying hypotheses 45

3.2. The ASEC scheme 50

3.3. The ASCTL scheme 54

3.4. The BESC scheme 57

3.5. The BASC scheme 66

3.6. Other schemes 74

3.7. General problems of kinetic analysis of polymer oxidation.
The outlines of a new approach 85

Chapter 4. Oxidation and Oxygen Diffusion 93

4.1. Properties of oxygen transport in polymers 93

4.2. The reaction/diffusion equation 101

Chapter 5. Stabilization 111

5.1. Principles of stabilization 111

5.2. Action on hydroperoxide decomposition 113

5.3. Stabilization by capture of P° radicals 117

5.4. Stabilization by capture of POO° radicals 119

5.5. Synergistic mixtures HD + CBA 125

5.6. Polyfunctional stabilizers 126

5.7. Hindered amines 127

5.8. Other stabilizing mechanisms 131

5.9. Physical aspects of stabilization by additives 131

Chapter 6. Molecular Mobility and Reactivity 145

6.1. The issue . 145

6.2. The chemical way . . 149

6.3. The physical way . . 154

6.4. Control by diffusion of macromolecular reactive species and
heterogeneity 158

6.5. The paradox of thermostability in glassy polymers 161

Chapter 7. Structural Changes Caused by Oxidation 163

7.1. On the molecular scale 163

7.2. On the macromolecular scale 175

7.3. On the morphological scale 192

Chapter 8. Effects of Oxidation on Physical and Mechanical
Properties 203

8.1. Introduction 203

8.2. Weight changes 204

8.3. Changes in density and volume 207

8.4. Optical properties 210

8.5. Electrical properties 215

8.6. Glass transition and melting 218

8.7. Mechanical properties at low strains 223

8.8. Fracture properties in the case of homogeneous degradation.
230

8.9. Fracture properties in the case of homogeneous crosslinking
243

Chapter 9. Couplings 249

9.1. Introduction 249

9.2. "Spontaneous" cracking 250

9.3. Coupling between cracking and oxidation 252

9.4. Lifetime under static strain and oxidation 254

9.5. Physical ageing and oxidation 264

9.6. Oxidation during processing - degradation and
recycling 266

Chapter 10. Oxidation Under Irradiation 277

10.1. Definitions. General aspects 277

10.2. Radiochemical initiation 283

10.3. A perculiarity of radiochemical ageing 288

10.4. Photochemical initiation 291

10.5. Photostabilization 300

10.6. Ageing under natural sunlight 308

Bibliography 321

Appendix 347

Index 353