Linear and non linear mechanical properties of miscible polymer blends near glass transition

Table of Contents

• Remerciements 4
• 1. 9
• General introduction 10
• 12
• 1. Introduction 12
• 1.1. What is a glass? 12
• 1.1.1. Non equilibrium aspects of the glass transition 13
• 1.1.2. Dynamic aspects of the glass transition 14
• 1.2. Glass transition: specificities in polymer materials 17
• 1.2.1. Structure of a polymer 17
• 19
• 1.2.2. Rubber elasticity 20
• 1.2.3. Linear properties in glassy polymers 25
• 1.2.4. Nonlinear properties in glassy polymers 29
• 1.2.5. Theoretical interpretations of plasticity 32
• 1.3. Miscible polymer blends 37
• 1.4. Problematics 41
• 43
• 2. Materials and methods 44
• 2.1. PB/SBR sample preparation 44
• 2.1.1. Structure 44
• 2.1.2. Blend preparation 45
• 2.1.3. Gluing to metal holders 45
• 2.2. Experimental techniques and sample geometries 46
• 49
• 50
• 3. Measurements of linear properties of the PB/SBR blends in the glass transition zone 50
• 3.1. Introduction 50
• 3.2. Overview of the samples and experimental techniques 51
• 3.3. Calorimetric properties of PB/SBR blends 52
• 3.3.1. Position and width of the glass transition 52
• 3.3.2. Influences of the crosslinking 54
• 3.3.3. Physical aging 55
• 3.4. Linear viscoelastic measurements 60
• 3.4.1. Rheological data 60
• 3.4.2. Time-temperature superposition 61
• 3.4.3. Influence of crosslinking and sample preparations 65
• 3.4.4. Broadening of the glass transition zone 68
• 3.5. Linear dielectric measurements 71
• 3.5.1. Main characteristics of the dielectric responses 71
• 3.5.2. -relaxation and -relaxation separation 74
• 3.5.3. Evolution of the position of-relaxation in PB/SBR blends 78
• 3.6. Conclusions on linear measurements 81
• 4. Interpretation of the linear properties of PB/SBR blends in the glass transition zone 82
• 4.1. Tg distribution P(Tg) from calorimetry 83
• 4.2. Microscopic organization: what length scale for glass transition? 87
• 4.2.1. Model description 87
• 4.2.2. Evolution of P(eff) with the length scale 89
• 4.2.3. Length scale of PB/SBR blends 91
• 4.3. Tg distribution and linear dielectric properties 94
• 4.3.1. How to relate P(Tg) to the macroscopic dielectric measurements? 94
• 4.3.2. Prediction of dielectric properties of PB/SBR blends 96
• 4.4. Tg distribution and linear properties: from DSC to rheology 99
• 4.4.1. Estimation of the viscoelastic spectra of a local domain of Tg. 100
• 4.4.2. Description of the macroscopic mechanical response of the blends 102
• 4.4.3. Conclusion on the interpretation of viscoelastic response and its relation to calorimetry 106
• 4.5. Conclusions on linear properties of PB/SBR blends 107
• 5. Nonlinear properties of PB/SBR blends in the glass transition zone 108
• 5.1. Experimental difficulties 108
• 5.1.1. Adiabatic self-heating 108
• 5.1.2. Non homogeneous deformation 110
• 5.2. Simple extension experiments 111
• 5.2.1. Measurement procedure 111
• 5.2.2. Determination of reliable experimental windows 111
• 5.2.3. Role of linear viscoelasticity in extension test 117
• 5.2.4. Nonlinearity in extension test 123
• 5.2.5. Evolution of structural nonlinearity 130
• 5.3. Cyclic shear Nonlinearities 132
• 5.4.1. Physical interpretation of Aent+Aplast 141
• 5.4.2. What is the relation between structural nonlinearity and plasticity? 144
• 6. General conclusion 149
• Résumé 152
• Annex A. Infrared camera and calibration 158
• Annex B. Kuhn lengths of PB and SBR 162
• Annex C. Calculation of heat transfer 164
• Annex D. Analytic form of viscoelastic relaxation 168
• Annex E. Determination of the evolution of the structural non linearity parameters Aent+Aplast 170
• Annex F. Details of cyclic shear measurements 173
• Annex G. Nonlinear time-temperature superposition in extension 179
• References 182