Question

Explain the molecular mechanisms behind the behaviour of a Bingham Plastic fluid.

Answer 1

Bingham plastics are the fluids that behave as a rigid body at low stresses but flows as a viscous liquid at high stress.

These type of fluids have the tendency to not to flow below a certain value known as yield stress and beyond this, the flow rate increases with increasing shear stress.

The molecular mechanisms behind this behaviour is that the liquid contains the solid particles such as polymers, clay etc. which have some kind of interaction creating a weak solid structure, also known as a false body . A certain amount of stress is required to break this structure which once broken will lead to the movement of particles under viscous forces.

Again on the removal of stress, the particles associate again forming a rigid body.