Introduction to Colloidal Dispersions


Applications In:

Almost all interesting materials and processes include multiple phases. When those phases are finely divided, as in paints, cosmetics, pharmaceuticals, reinforced plastics and rubbers, foods, ceramics, and all life forms, colloidal properties become significant.  

Who Should Attend:

Scientists and engineers engaged in research and development in the chemical, petroleum, coatings, food, electronics, pharmaceutical, cosmetics, and ceramics industries whose primary assignments are not directly related to colloid chemistry. However, as is so often true in industrial research, development, and engineering, these assignments require a practical understanding of the general principles of colloid chemistry. This course is for those scientists and engineers. …

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Introduction to Colloidal Dispersions

Overview: 

This short course covers some of the armory of concepts and techniques that are available in colloid chemistry, so that investigators may orient their thinking along lines already laid down by the experience of previous workers. With a specific problem in mind, the goal is to find the appropriate context to help formulate it.

· Principles that are relevant to the formation and stability of dispersions of fine particles (suspension), dispersions of liquids (emulsions), and dispersions of gas (foams)

· Experimental methods to measure particle size, dispersion stability, rheological, and electrokinetic properties.

· Principles that are relevant to the formation and stability of dispersions of fine particles (suspension), dispersions of liquids (emulsions), and dispersions of gas (foams).

· Factors that determine dispersibility and stability to flocculation and sedimentation.

· Methods to stabilize or destabilize fine dispersions in both aqueous and nonaqueous liquids.

· Dispersion processing, including commercial equipment.

Topics Covered: 

Day 1

Surfactant science and technology 

Adsorption at surfaces and interfaces, etymology of terms, common surfactants, their classification and structures, dynamic surface effects, micelles and liquid crystals, critical micelle concentrations, Krafft temperatures, phase inversion temperatures, adsorption from solution, adsorption of polymers.

Wetting, spreading, and adhesion 

Origin of surface tension, coalescence, spreading, detergency, contact angles and theYoung-Dupré equation, works of adhesion and cohesion, Laplace pressures, capillary rise, nucleation, Ostwald ripening, and Marangoni effects.

Particles, drops, and bubbles 

Brownian motion and diffusion, particle size and size distributions, microscopy, optical sensors, Coulter counter, light scattering, quasi-elastic light scattering, sedimentation, acoustic sensing and sizing, centrifugation, hydrodynamic chromatography, field flow fractionation, zeta potential measurements, electroacoustics, rheology. shear thickening, shear thinning, viscoelasticity.

Day 2 

Interparticle forces and stability 

Rates of flocculation. Forces of attraction: dispersion forces, Hamaker theory, Lifshitz theory. Steric stabilization: criterion of steric stabilization, polymer layers, adsorption of polymers, acid-base interaction. Electrostatic repulsion: model of a charged particle, criterion of electrostatic, stabilization, ionic strength, DLVO theory, effect of electrolytes, critical coagulation concentration (CCC), Schulze-Hardy rule, particle size effects, electrostatic stabilization in non-polar liquids, electrosteric repulsion. Mechanisms of flocculation.

Emulsion and foam technology 

Emulsion terminology, surface activity in emulsions, stability of emulsions, demulsification, inversion of emulsions, Bancroft’s rule, HLB schema, phase inversion temperatures, multiple emulsions, physical properties of emulsions, measurements of emulsion interfaces, making of emulsions, intermittent milling.

Bubble geometries, foam structures, formation of bubbles, formation of foams, foam drainage and stability, measurements of foam films, equation of state for foams, foam stability, foaming and the phase diagram, foam inhibition and breaking, antifoams.

Processing suspensions and emulsions 

High speed mixers, rotor-stators, colloid mills, homogenizers, ultrasonic dispersers, roll mills, ball and roller mills, attritors, and sand mills.

Textbook 

Colloidal Dispersions: Suspensions, Emulsions, and Foams
John Wiley & Sons: New York (2002)
Available at:

http://www.colloidaldispersions.com/textbook/textbook_order.html

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Instructor

Ian Morrison is a Fellow at Cabot Corporation (since 2002). Prior to this he was Director of Technology at E Ink Corporation (4 years) and Principal Scientist at Xerox Corporation (21 years). He has taught the ACS short course on dispersions since 1985. His research has been on powder technology, including gas adsorption, surface area and surface uniformity, the surface energy of powders, particle size distributions by QELS, and nanoparticles, as well as on nonaqueous dispersions, electrical effects in nonaqueous media, flocculation and crystal growth, and capillarity. He has led commercial programs on particle-based displays, electrophotography, specialty inks and toners, and coatings. He is the author of more that 75 publications and patents. He has published, with Professor Sydney Ross, two textbooks, the latest, Colloidal Dispersions, in 2002. He has a BS in Chemistry (1971) and Mathematics (1973), a MS in Physical Chemistry (1972), and a PhD in Colloid and Interface Science (1975) all from Rensselaer Polytechnic Institute in Troy, NY.
 

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(C)  2007  Particles Conference