Microstructure and Viscosity of Aggregating Colloids under Strong Shearing Force

Area of Science:

• Colloid science
• Rheology
• Computational physics

Background:

• Colloidal systems aggregate and disaggregate under various forces.
• Understanding these dynamics is crucial for material science and industrial processes.
• Existing models may lack the ability to capture kinetics, deformation, and rupture simultaneously.

Purpose of the Study:

• To simulate disaggregation of aggregating colloids under strong shear forces.
• To develop a minimal parameter model for describing colloid cluster dynamics.
• To investigate the relationship between microstructure, viscosity, and coordination number under shear flow.

Main Methods:

• Utilized a sticky particle model for simulating aggregating and disaggregating colloids.
• Performed 2-dimensional simulations to calculate viscosity and coordination number over time.
• Visualized particle configurations to observe microstructural changes with shear flow.

Main Results:

• Viscosity is dependent on both area fraction and shear rate.
• Coordination number is solely dependent on the shear rate.
• Steady-state viscosity and coordination number are independent of initial particle states, indicating reversibility.

Conclusions:

• The sticky particle model effectively describes colloid disaggregation and aggregation kinetics.
• Shear forces play a critical role in determining the rheological properties of colloids.
• The observed reversibility suggests a dynamic equilibrium in colloidal systems under shear.