August 2 and 3, 2008 (Saturday and Sunday)
Jan Mewis, Professor Emeritus
Department of Chemical Engineering
K. U. Leuven
Belgium
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Norman Wagner, Professor
Department of Chemical Engineering
University of Delaware
USA
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With over 50 years of academic and industrial research experience in the
colloid rheology laboratory, including over 100 publications and patents on the
topic, Professors Mewis and Wagner have prepared a short course designed for
introducing a beginning colloid rheologist to the field. This course is based on
a text currently in progress. Both have lectured extensively on the topic and
have taught short courses at both the beginner and more advanced levels,
including courses for The Society of Rheology in the US and the European
Rheology Society in Europe.
For additional information, visit the web pages of
Prof. Mewis
and Prof.Wagner.
The course is designed to be an introduction to the rheology of colloidal
dispersions with emphasis on practical measurement and interpretation of
rheological measurements on colloidal dispersions. The object is to provide the
participants with:
- Qualitative understanding of the various phenomena that contribute to
the rheology of suspensions;
- Scaling relations and quantitative laws to predict the basic rheology of
such systems;
- Strategies to measure, characterize and design suspensions with well
defined processing or application properties.
This course is of interest to students and practitioners of colloid rheology
in industry as well as academia. A basic understanding of physical chemistry is
necessary with some familiarity with colloidal science and basic rheology
helpful but not required.
The course is structured so as to build systematically upon the fundamental understanding of
how various properties of colloids and their interactions lead to the observed
rheological behaviour. This starts with systems where
only purely hydrodynamic effects are present (i.e. suspensions with
non-colloidal particles). Next, colloidal particles are introduced; with
Brownian motion but without any particle interaction force. After that systems
with additionally repulse interparticle forces are dealt with: i.e. colloidally
stable systems. Finally attractive forces are added which can lead to
flocculated suspensions and colloidal gels. The methods of rheological
measurement design and execution are discussed, treating the special
difficulties that arise in the case of suspensions. Case studies will be
analyzed to illustrate the basic concepts of the course. Finally, special
advanced topics are to be included depending on the interest of the students.
Time is available for a question and answer session based on problems and
issued submitted by students prior to the course.
- Rheological Concepts and Rheological Phenomena in Colloidal Dispersions
(1.5 hrs)
- Basic rheological concepts
- Overview of rheological phenomena in suspensions (based on case studies)
- Hydrodynamic Effects (Suspensions of Large Particles) (1 hrs)
- Dilute systems: Relative viscosity and Einstein relation
- Semi-dilute systems: Batchelor relation
- Concentrated systems (maximum packing, viscosity-concentration
relations, effect of particle size distribution)
- Suspensions of Brownian Particles (1.5 hrs)
- Mechanism of Brownian motion
- Contribution of Brownian motion to the viscosity
- Viscoelasticity in suspensions of Brownian Hard Spheres (scaling
relations)
- Colloidally Stable Suspensions (2 hrs)
- Electrostatic and Steric stabilization, resulting suspension
structure
- Effect of interparticle repulsion on dilute suspensions
- Viscosity of concentrated stable suspensions, scaling relations
- Viscoelastic effects, link to interparticle potential, scaling
relations
- Shear thickening
- Flocculated Suspensions (2 hrs)
- Mechanisms of flocculation (electrostatic, depletion, bridging…)
- Structure of flocculated systems (flocs, agglomerates, particle
gels; their description in RDF, fractals, percolation theory, stat
diagrams).
- Viscosity of dilute, flocculated systems
- Gels and glasses
- Thixotropy (reversible time effects)
- Rheological Measurements of Suspensions (1.5 hrs)
- Special requirements and problems (based on case studies)
- Measurement strategies
- Formulation of suspensions for controlled rheology (1.5 hrs)
- Design rules for formulation suspensions with a given rheology
(based on case studies)
- Advanced Topics in Colloidal Suspension Rheology (depending on student
preferences) (2-3 hrs)
- Suspension in viscoelastic media (filled polymers, nanocomposites)
- Suspensions containing non-spherical particles (fibers, rods, ...)
- Microrheology
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