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Polymer Blends and Alloys
CONTENTS
CHAPTER 0
IMPROVED PROPERTIES OF POLYMERIC MATERIAL BY MEANS
OF MIXING TWO POLYMERS 1
1 Introduction 1
1.1.1 Theory of compatibilisation 2
1.1.2 Mechanical properties of blends 3
1.2 What has been done in earlier work 3
2 This thesis 7
References 8
CHAPTER 1
A NEW METHOD FOR REACTIVE BLENDING 10
Abstract 10
1 Introduction 10
2 Theory 11
2.1 Experimental set-up 13
2.2 Analysis 13
3 Experimental results 14
4 Concentration profiles 17
4.1 The materials formed in the dispersed phase 20
5 Conclusions 23
Nomenclature 23
References 24
CHAPTER 2
THREE DIMENSIONAL FLOW MODELLING OF A SELF WIPING
COROTATING TWIN SCREW EXTRUDER, THE KNEADING SECTION
25
Abstract 25
1 Introduction 25
2 Mathematical method 26
3 Definition of the problem 28
3.1 Geometry and mesh 28
3.2 Boundary conditions 30
4 Results 31
4.1.1 The axial velocities 31
4.1.2 The axial backflow volume 32
4.2 The transverse velocities 34
4.3 The pressure difference over one kneading element 35
4.4 The shear and elongation rate 37
4.5 The influence of the stagger angle between the kneading elements
on the flow 39
4.6 The influence of the viscosity on the flow 43
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4.7 The adiabatic axial temperature rise 45
4.8 Experimental validation 46
5 Discussions and conclusions 47
Nomenclature 48
References 49
CHAPTER 3
THREE DIMENSIONAL FLOW MODELLING OF A SELF WIPING
COROTATING TWIN SCREW EXTRUDER, THE TRANSPORTING
SECTION
51
Abstract 51
1 Introduction 51
2 Mathematical method 53
3 Definition of the problem 55
4 Results and discussion 57
4.1 The throughput 57
4.2 The flow profile 58
4.3 The backflow 61
4.4 The axial pressure gradient 63
4.5 The shear and elongation rate 64
4.6 The adiabatic temperature rise 67
4.7 The influence of viscosity 68
5 Conclusions 71
Nomenclature 71
References 73
CHAPTER 4
THREE DIMENSIONAL FLOW AND TEMPERATURE MODELLING IN
THE CHANNEL OF THE COROTATING TWIN SCREW EXTRUDER
74
Abstract 74
1 Introduction 74
2 Definition of the problem 75
2.1 The geometric model 75
2.2 The flow problem 77
2.3 The temperature problem 78
2.4 The temperature profile for a larger length of the channel 79
3 Results 79
3.1 Three dimensional temperature calculation, an example 80
3.2 The influence of the heat conductivity coefficient 86
3.3 The influence of reaction heat on the temperature profile 88
4 Conclusions 90
Nomenclature 90
References 91
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CHAPTER 5
THE ROLE OF DIFFUSION AND REACTION IN REACTIVE
COMPOUNDING
92
Abstract 92
1 Introduction 92
Diffusion 92
Kinetics 93
Modelling 93
2 Experimental set-up 94
2.1 The measurements of the diffusion coefficient with FRAP 95
3 Results 97
3.1.1 The diffusion coefficient 97
3.1.2 Variation of the temperature 98
3.1.3 Diffusion coefficients of binary diffusion in a polymer 102
3.2.1 Kinetics 105
3.2.2 Measurements of the reaction velocities 106
4 Modelling the concentration profiles and Mn
distribution of
the alloying agent 107
5 Discussion and conclusions 112
Nomenclature 114
References 114
CHAPTER 6
MODELLING AND EXPERIMENTAL EVALUATION OF THE
TEMPERATURE IN A COROTATING TWIN SCREW EXTRUDER
115
Abstract 115
1 Introduction 115
2 Modelling of the average axial temperature in the corotating
twin screw extruder 116
2.1 The geometry and the throughput of the extruder 116
2.2 The temperature model 119
2.3 The viscous dissipation 119
2.4 The temperature profile 120
3 Experimental 122
3.1 Extrusion and viscosity 122
4 Results 123
4.1 The power 123
4.2.1 The temperature profile in the partially filled section 126
4.2.2 The fully filled section 128
4.2.3 The temperature at the entrance of the kneading section 130
4.2.4 The heat transfer coefficient calculated ; the kneading section 132
4.2.5 The temperature of a blend (PS/HDPE) 133
5 Conclusions 135
Nomenclature 135
References 137
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CHAPTER 7
MODELLING AND EXPERIMENTAL EVALUATION OF MIXING IN A
COROTATING TWIN SCREW EXTRUDER
138
Abstract 138
1 Introduction to mechanical properties of blends 138
1.1 Mixing in the intermeshing corotating twin screw extruder 139
2 Modelling of mixing in the corotating-twin screw extruder 140
2.1.1 A simplified modelling of the average size of the dispersed phase of a blend
142
2.1.2 Modelling of the average size of the dispersed phase of a blend 144
3 Experimental set up 146
4 Results and discussions 147
4.1 Modelling of the axial development of the average size of the dispersed phase
147
4.2 The influence of the rotation speed of the screws 152
4.3.1 Comparison between measurements and modelling, PS/HDPE blends 155
4.3.2 Comparison of our computer modelling with the measurements of others 156
5 Conclusions 157
Nomenclature 158
References 159
CHAPTER 8
MODELLING AND EXPERIMENTAL EVALUATION OF REACTIVE
COMPOUNDING IN A COROTATING TWIN SCREW EXTRUDER
161
Abstract 161
1 Introduction 161
2 Modelling reactive compounding 164
2.1 The different steps taken in our modelling 164
2.2 Measuring and modelling the reaction velocity of monomer in the melt,
an example 166
2.3 Modelling and measuring the size of the dispersed phase, an example 170
2.4 Modelling of the diffusion of monomer out of the dispersed phase
, an example 171
2.5 Modelling of the conversion of monomer in the dispersed phase 171
3 Experimental set-up 172
3.1 Experiments with the Brabender mixing chamber 173
3.2 Reactive blending in the extruder 174
3.3 Reactive blending of PS/PP with MAH/S 175
3.4 Experiments with an improved screw geometry 176
4 Comparison between model and experiments 178
4.1 The measured and modelled conversions of MAH in the
dispersed phase (HDPE) versus rotation speed and throughput 179
4.2 The conversion of acrylates in the dispersed phase of PS/HDPE 180
5 The grafted monomer on HDPE in the dispersed phase of PS/HDPE 182
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6 Conclusions 185
Nomenclature 186
References 186
CHAPTER 9
IMPROVED TOUGHNESS VERSUS PROCESSING PARAMETERS
188
Abstract 188
1 Introduction 188
1.1 Theory, mechanical properties and morphology 189
1.2 The conversion in the dispersed phase of a PS/HDPE blend 190
2 Experimental set-up, the extruder 192
2.1 Experimental set-up, the materials 192
2.2 Analysis 193
3 Results 193
3.1 Material choice for the dispersed and matrix phase 194
3.2 Material properties versus processing conditions 194
3.3 Toughness and elongation at break 197
3.4 The influence of rotation speed on the Notched Izod Impact values 199
3.5 Impact values versus conversion and rotation speed 202
3.6 The relation between elongation at break, and an efficient alloying agent 203
4 Discussion 207
5 Conclusions 209
Nomenclature 210
References 210
CHAPTER 10
THE LINK BETWEEN THE GLASS TRANSITION TEMPERATURE, THE
ALLOYING AGENT FORMED, AND THE MECHANICAL PROPERTIES OF
THE BLEND
211
Abstract 211
1 Introduction 211
2 Experimental 215
2.1 Analysis 216
3 Results 217
3.1 The conversion of monomer in the dispersed phase 217
3.2 The glass and melt transition temperature and toughness versus the rotation
speed of the screws 220
4 The Notched Izod Impact value, Tg
, and the alloying agent 226
5 The influence of the type of dispersed phase 229
6 Conclusions 230
6.1 Theoretical considerations 231
Nomenclature 232
References 232