DISPERSIONS Characterization, Testing,

and Measurement

Erik Kissa Consultant

Wiimington, Delaware

M A R C E L

'I MARCEL DEKKER, INC. NEW YORK • BASEL

D E X K E R

Contents

I. II.

III. IV.

Terminology Dispersed Phase Dispersion Medium Formation of Dispersions References

PREFACE iii

1. DISPERSION: THE SYSTEM 1 1 4 6 6 7

PART I. CHARACTERIZATION OF PARTICLES

2. PARTICLE CHARACTERIZATION 8 I. Particle Shape 8

IL Particle Size 14 References 41

3. PHYSICAL SURFACE CHARACTERIZATION 47 I. Surface Area Measurement 47

IL Morphology and Porosity 70 References 85

4. CHEMICAL CHARACTERIZATION OF PARTICLE SURFACES 93

I. Surface Analysis 93 IL Spectroscopy 100

III. Titration Methods 108 IV. Adsorption from Solution 119

References 128

V I Contents

5. WETTABIXITY 137 I. Wetting 137

II. Direct Determination of Contact Angle 144 III. Indirect Contact Angle Measurement 151 IV. Immersion Tests 159 V. Calorimetry 161

VI. Miscellaneous Tests 161 VII. Wetting of Powders by Dispersants 165

References 169

PART II. CHARACTERIZATION OF DISPERSIONS

6. STABILIZATION WITH DISPERSANTS AND DISPERSIBILITY 173 I. Stabilization of Dispersions 173

II. Dispersants 181 III. Adsorption of Dispersants 194 IV. Configuration of Adsorbed Dispersants 205 V. Dispersibility 216

References 229

7. PREPARATION AND TESTING OF DISPERSIONS 237 I. Preparation of Dispersions 237

II. Qualitative and Semiquantitative Dispersion Tests 243 III. Quantitative Dispersion Tests 247 IV. Dispersion Stability and Redispersion 259 V. Toxicity and Environmental Aspects 274

References 275

8. FLOCCULATION AND COAGULATION 282 I. Theory 282

II. Techniques of Measurement 289 III. Critical Coagulation Concentration 302 IV. Flocculation with Polymers 309

References 335

9. SEDIMENTATION 345 I. Gravitational Sedimentation 345

IL Centrifugal Sedimentation 369 III. Sedimentation Volume 387

References 391

PART III. METHODS AND TECHNIQUES

10. MICROSCOPYN 399 I. Optical Microscopy 399

IL Electron Microscopy 410 III. Image Analysis 416

Contents vii

IV. Probe Microscopy 419 References 427

11. RADIATION SCATTERING 433 I. Light Scattering Methods 433

IL Static (Elastic) Light Scattering 435 III. Turbidity 440 IV. Dynamic Light Scattering (Photon Correlation Spectroscopy,

Quasielastic Light Scattering) 449 V. Phase-Doppler Anemometry and Velocimetry -, 469

VI. Light Diffraction 472 VII. Back-Scatter Techniques 478

VIII. Small-Angle Scattering Methods 480 IX. Single-Particle Optical Sensing 483 X. Electrooptics 489

References 492

12. CHROMATOGRAPHY 502 I. Hydrodynamic Chromatography 502

IL Field Flow Fractionation 507 III. Size Exclusion Chromatography 529 IV. Gas Chromatography 529 V. Liquid Chromatography 531

References 532

13. ELECTROCHEMICAL METHODS 538 I. Surface Charge 538

IL Determination of Surface Charge by Titration 542 III. Electrokinetic Measurements: Zeta Potential 549 IV. Dynamic Mobility 571 V. Electrical Conductivity and Dielectric Characteristics 581

VI. Electrical Sensing Zone Method 587 References 594

14. RHEOLOGY 603 I. Theory 603

IL Measurement of Viscosity 610 III. Rheology of Structured Systems 633 IV. Thixotropy and Rheopexy 643 V. Yield Stress 647

VI. Rheology of Aggregated Systems 654 VII. Electroviscosity and Electrorheology 662

VIII. Rheology of Practical Systems 664 References 682

INDEX 695