Yield Stress Sedimentation and Linearity

The non-linear response of plastic materials is more challenging in many respects than pseudoplastic materials. While some yield phenomena, such as that seen in clay dispersions of montmorillonite, can be catastrophic in nature and recover very rapidly, others such as polymer particle blends can yield slowly. Not all clay structures catastrophically thin. Clay platelets forming an elastic structure can be deformed by a finite strain such that they align with the deforming field. When the strain 

For a concentrated dispersion the particles feel the effects of all their neighbours and the sedimentation velocity can be represented semi-empirically as8 

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