Suspension Concentrates: Preparation, Stability and Industrial Applications
362
Suspension Concentrates: Preparation, Stability and Industrial Applications
362Paperback
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Overview
Product Details
| ISBN-13: | 9783110486780 |
|---|---|
| Publisher: | De Gruyter |
| Publication date: | 02/20/2017 |
| Series: | De Gruyter Textbook |
| Pages: | 362 |
| Product dimensions: | 6.69(w) x 9.45(h) x (d) |
| Age Range: | 18 Years |
About the Author
Table of Contents
Preface v
1 General introduction 1
2 Preparation of suspension concentrates by the bottom-up process 13
2.1 Introduction 13
2.2 Preparation of suspensions by precipitation 14
2.2.1 Nucleation and growth 15
2.2.2 Precipitation kinetics 17
2.2.3 Seeded nucleation and growth 22
2.2.4 Surface modification 22
2.2.5 Other methods for preparation of suspensions by the bottom-up process 23
2.3 Characterization of suspension particles 30
2.3.1 Visual observations 30
2.3.2 Optical microscopy 31
2.3.3 Electron microscopy 33
2.3.4 Confocal laser scanning microscopy (CLSM) 34
2.3.5 Scanning probe microscopy (SPM) 35
2.3.6 Scanning tunnelling microscopy (STM) 35
2.3.7 Atomic force microscopy (AFM) 36
2.3.8 Scattering techniques 36
2.4 Measurement of charge and zeta potential 43
3 Preparation of suspensions using the top-down process 53
3.1 Wetting of the bulk powder 54
3.2 Breaking of aggregates and agglomerates into individual units 58
3.3 Wet milling or comminution 63
3.4 Stabilization of the suspension during dispersion and milling and the resulting nanosuspension 68
3.5 Prevention of Ostwald ripening (crystal growth) 72
4 Electrostatic stabilization of suspensions 75
4.1 Introduction 75
4.2 Structure of the solid/liquid interface 75
4.2.1 Origin of charge on surfaces 75
4.2.2 Specific adsorption of ions 79
4.3 Structure of the electrical double layer 79
4.3.1 Diffuse double layer (Gouy and Chapman) 79
4.3.2 Stern-Grahame model of the double layer 82
4.4 Electrical double layer repulsion 83
4.5 Van der Waals Attraction 91
4.6 Total energy of interaction 98
4.6.1 Deryaguin-Landau-Verwey-Overbeek(DLVO) theory 98
4.7 Criteria for stabilization of suspensions with double layer interaction 100
5 Steric stabilization of suspensions 103
5.1 Introduction 103
5.2 Adsorption and orientation of nonionic surfactants at the solid/liquid interface 103
5.3 Polymeric surfactant adsorption 106
5.4 Interaction between particles containing adsorbed surfactant layers 112
6 Flocculation of suspensions 119
6.1 Introduction 119
6.2 Kinetics of flocculation of electrostatically stabilized suspensions 120
6.2.1 Diffusion limited aggregation (fast flocculation kinetics) 120
6.2.2 Potential limited aggregation (slow flocculation kinetics) 122
6.2.3 Weak (reversible) flocculation 123
6.2.4 Orthokinetic flocculation 124
6.2.5 Aggregate structure 128
6.3 Flocculation of sterically stabilized dispersions 129
6.3.1 Weak flocculation 129
6.3.2 Incipient flocculation 129
6.3.3 Depletion flocculation 131
6.3.4 Bridging flocculation by polymers and polyelectrolytes 133
7 Ostwald ripening in suspensions 137
7.1 Driving force for Ostwald ripening 137
7.2 Kinetics of Ostwald ripening 138
7.3 Thermodynamic theory of crystal growth 142
7.4 Molecular-kinetic theory of crystal growth 145
7.5 The influence of dislocations on crystal growth 145
7.6 Influence of impurities on crystal growth and habit 146
7.7 Polymorphic changes 147
7.8 Crystal growth inhibition 148
8 Sedimentation of suspensions and prevention of formation of dilarant sediments 153
8.1 Introduction 153
8.2 Sedimentation rate of suspensions 154
8.2.1 Very dilute suspensions 154
8.2.2 Moderately concentrated suspensions 154
8.2.3 Concentrated suspensions 155
8.2.4 Sedimentation of flocculated suspensions 158
8.2.5 Sedimentation in non-Newtonian fluids 160
8.3 Prevention of sedimentation and formation of dilatant sediments 164
8.3.1 Balance of the density of the disperse phase and medium 164
8.3.2 Reduction of particle size 164
8.3.3 Use of high molecular weight thickeners 164
8.3.4 Use of "inert" fine particles 166
8.3.5 Use of mixtures of polymers and finely divided particulate solids 169
8.3.6 Controlled flocculation ("self-structured" systems) 170
8.3.7 Depletion flocculation 174
8.3.8 Use of liquid crystalline phases 178
9 Rheology of suspensions 181
9.1 Introduction 181
9.2 Rheological techniques 182
9.2.1 Steady state measurements 183
9.2.2 Rheological models for analysis of flow curves 184
9.2.3 Time effects during flow - thixotropy and negative (or anti-) thixotropy 186
9.2.4 Constant stress (creep) measurements 187
9.2.5 Dynamic (oscillatory) measurements 191
9.3 Rheology of suspensions 195
9.3.1 Dilute suspensions (φ ≥ 0.01) - the Einstein equation 195
9.3.2 Moderately concentrated suspensions (0.2 > φ > 0.01) -the Bachelor equation 196
9.3.3 Rheology of concentrated suspensions 196
10 Nonaqueous suspension concentrates 235
10.1 Introduction 235
10.2 Stability of suspensions in polar media 236
10.3 Stability of suspensions in nonpolar media 238
10.4 Characterization of the adsorbed polymer layer 239
10.5 Theory of steric stabilization 239
10.6 Criteria for effective steric stabilization 242
10.7 Settling of suspensions and preventing the formation of dilatant sediments 243
10.8 Examples of suspending agents that can be applied for prevention of settling in nonaqueous suspensions 244
10.9 Em unification of oil-based suspensions 246
10.10 Mechanism of spontaneous emulsification and the role of mixed surfactant film 247
10.11 Polymeric surfactants for oil-based suspensions and the choice of emulsifiers 250
10.12 Emulsification into aqueous electrolyte solutions 250
10.13 Proper choice of the antisettling system 251
10.14 Rheologicat characteristics of the oil-based suspensions 251
11 Characterization, assessment and prediction of stability of suspensions 253
11.1 Introduction 253
11.2 Assessment of the structure of the solid/liquid interface 254
11.2.1 Double layer investigation 254
11.3 Measurement of surfactant and polymer adsorption 268
11.4 Assessment of sedimentation of suspensions 271
11.5 Assessment of flocculation and Ostwald ripening (crystal growth) 274
11.5.1 Optical microscopy 274
11.5.2 Sample preparation for optical microscopy 275
11.5.3 Particle size measurements using optical microscopy 275
11.5.4 Electron microscopy 276
11.5.5 Confocal laser scanning microscopy (CLSM) 277
11.5.6 Scanning probe microscopy (SPM) 278
11.5.7 Scanning tunnelling microscopy (STM) 278
11.5.8 Atomic force microscopy (AFM) 279
11.5.9 Scattering techniques 279
11.6 Measurement of rate of flocculation 286
11.7 Measurement of incipient flocculation 287
11.8 Measurement of crystal growth (Ostwald ripening) 288
11.9 Bulk properties of suspensions, equilibrium sediment volume (or height) and redispersion 289
11.10 Application of Theological techniques for the assessment and prediction of the physical stability of suspensions 289
11.10.1 Rheological techniques for prediction of sedimentation and syneresis 289
11.10.2 Role of thickeners 291
11.10.3 Assessmentand prediction of flocculation using rheological techniques 292
11.10.4 Examples of application of rheology for assessment and prediction of flocculation 296
12 Application of suspensions in pharmacy 299
12.1 Introduction 299
12.2 Particle size reduction 299
12.3 Dispersion and stabilization of the drug suspension 301
12.4 Colloid stability of pharmaceutical suspensions 302
12.5 Prevention of Ostwald ripening (crystal growth) 303
12.6 Prevention of particle settling and suspension separation 305
12.7 Oral suspensions 305
12.8 Parenteral suspensions 306
12.9 Ophthalmic suspensions 306
12.10 Topical suspensions 306
12.11 Reconstitutable suspensions 307
13 Applications of suspensions in cosmetics and personal care 311
13.1 Introduction 311
13.2 Suspensions in sunscreens 311
13.3 Suspensions in colour cosmetics 315
13.4 Lipsticks and lip balms 322
13.5 Nail polish 322
13.6 Antiperspirants and deodorants 323
13.7 Foundations 323
13.8 Liquid detergents 324
14 Application of suspensions in paints and coatings 325
14.1 Introduction 325
14.2 The disperse particles 325
14.3 The dispersion medium and film formers 328
14.4 Deposition of particles and their adhesion to the substrate 330
14.5 Flow characteristics (rheology) of paints 330
15 Application of suspensions in agrochemicals 333
15.1 Introduction 333
15.2 Preparation of suspension concentrates and the rote of surfactants/dispersing agents 333
15.3 Control of the physical stability of agrochemical suspension concentrates 335
15.4 Ostwald ripening (crystal growth) 339
15.5 Stability against claying or caking 340
Index 343