Seminars

ACA Systems provides popular rheology seminars. They can be arranged also on customers' site at request. Please contact us for more information.

The Contents of the Rheology Seminar

Fundamentals of Rheology

1. Viscosity and elasticity

  • 1.1 Viscosity
  • 1.2 Elasticity

2. Flow curves and common rheological models

  • 2.1 Newtonian fluids
  • 2.2 Shear thinning fluids
  • 2.3 Shear thickening fluids
  • 2.4 Mathematical models for describing flow behavior
    • 2.4.1 Power law
    • 2.4.2 Cross model
    • 2.4.3 Bingham model
  • 2.5 Thixotropy and rheopexy
  • 2.6 Reynolds number: laminar and turbulent flow

3. Viscoelasticity

  • 3.1 Deporah number
  • 3.2 Viscoelasticity and oscillatory shear test
  • 3.3 Extensional viscosity
  • 3.4 Normal forces

Rheology of Coating Colors

1. General description

  • 1.1 Surface chemistry
  • 1.2 Hydrodynamic factors
  • 1.3 Examples of hydrodynamic vs. chemical factors
    • 1.3.1 Effect of gypsum
    • 1.3.2 Effect of different cobinders

2. Effect of coating color components

  • 2.1 Pigment
    • 2.1.1 Effect of particles in a suspension
    • 2.1.2 Effect of solids content
    • 2.1.3 Effect of size and size distribution of particles
    • 2.1.4 Effect of the shape of the pigment particles
  • 2.2 Latex
    • 2.2.1 Example: effect of particle size of latex to viscosity
    • 2.2.2 Example: Total particle size distribution
  • 2.3 Thickeners and cobinders
  • 2.4 Dispersants

Coating Process and Viscometers

1. Significance of rheology

  • 1.1 Brief description of rheological requirements and shear rates during the process

2. Viscometers and their suitability

  • 2.1 Brookfield viscometer
  • 2.2 High shear rotational viscometers
  • 2.3 High shear capillary viscometers
    • 2.3.1 Bagley correction: Measurement of extensional viscosity
    • 2.3.2 Wall slip: measurement of dynamic water retention
  • 2.4 Slit die viscometers
    • 2.4.1 Stability test with a slit
  • 2.5 Comparison of viscometers

Rheological Requirements of Coating Process I

1. Pigment coating methods

2. Application of coating color in blade coating

  • 2.1 Application methods and requirements
  • 2.2 Application process and Reynolds number
  • 2.3 Roll application
    • 2.3.1 Roll application: Shear rate and rheology
  • 2.4 Short dwell time application
    • 2.4.1 Short dwell time application: shear rate and rheology
  • 2.5 Jet application
    • 2.5.1 Jet application: shear rate and rheology
  • 2.6 Dewatering during the coating process.
    • 2.6.1 Dewatering: comparison of application

3. Metering of coating color with the blade

  • 3.1 Shear rate under the blade
  • 3.2 Viscosity and coat weight development
    • 3.2.1 Model for coat weight development
    • 3.2.2 Significance of viscosity
    • 3.2.3 Example of correlation between viscosity and blade load: traditional viscometers.
    • 3.2.4 Example of correlation between viscosity and blade load: Slit and capillary viscometers.

Rheological Requirements of Coating Process II

1. Blade coating

  • 1.1 Blade coating defects
    • 1.1.1 Scratches
    • 1.1.2 Dry Bleeding (stalagmites)
    • 1.1.3 Wet bleeding
    • 1.1.4 Streaks
  • 1.2 Effect of Non-Newtonian rheology
    • 1.2.1 Extensional (elongational) viscosity
    • 1.2.2 Normal forces
    • 1.2.3 Elasticity
  • 1.3 Summary and conclusions

2. Film transfer coating

  • 2.1 Premetering of coating color
  • 2.2 Film transferring onto the paper
  • 2.3 Film splitting
    • 2.3.1 Misting at the outlet of the nip
    • 2.3.2 Orange peel formation
  • 2.4 Summary

3. Screening

  • 3.1 Shear rate during the screening
  • 3.2 An example of screening problems

Interpretation of Flow Curves and Coating Color Development

1. Interpretation of ultrahigh shear rate flow curves

  • 1.1 Viscosity level
  • 1.2 Shape of the viscosity curve
  • 1.3 Remarks on interpretation of viscosity curves
    • 1.3.1 Viscosity vs. shear rate and shear rate vs. shear stress
    • 1.3.2 Effect of solids content
    • 1.3.3 Effect of temperature
  • 1.4 Practical examples
    • 1.4.1 Adjusting of viscosity level by using thickener
    • 1.4.2 Interpretation of viscosity curves of acrylic adhesives

2. Coating color development

  • 2.1 Rheological properties of optimum coating color
  • 2.2 Examples
    • 2.2.1 Increasing productivity by optimizing coating color
    • 2.2.2 Improving optical properties by adjusting particle size distribution of pigment and latex.