Concentrated Suspension Viscosity: State the Packing-Fraction Boundary

Identify the Deformation and Model

Malvern Panalytical describes concentration-based suspension models containing maximum packing fraction φₘ and particle-dependent parameters. Approaching this model boundary differs from a dilute linear correction. Primary reference: packing and suspension rheology.

Review a Hypothetical Comparison

At invented actual particle volume fraction φ = 0.30, choosing φₘ = 0.60 gives reduced fraction φ/φₘ = 0.50. Choosing φₘ = 0.75 gives 0.40 at the same actual loading. Thus the model proximity to packing changes even though no solid inventory was added. These assigned limits are not measured properties or universal values.

Keep the Evidence with the Decision

Retain the complete constitutive expression and the evidence used to choose φₘ. Identify particle shape, interactions, size mixture and imposed-flow conditions relevant to that value. Distinguish a fitted packing parameter from a separately measured maximum packing state. Plot the proposed range against the model boundary and check how uncertain parameters affect a prediction near it.

An apparent mathematical divergence does not identify a universal operational jam point for every real suspension. Other mechanisms can change the response before the fitted boundary is approached. No viscosity, pump pressure or HM formulation limit follows from the two reduced fractions alone. The worksheet should document the packing assumption so an actual loading change is not confused with a model-parameter change.

Does the chosen model recognize the approach to a formulation-dependent packing limit?

This blank worksheet is for your own project. It contains no H M machine trial result.

Customer Questions

Primary References

These references support the technical principles discussed in this guide. The worked examples and review questions are educational.

• Primary reference: packing and suspension rheology
• Reference from hmpharmamachines.com