Rheology:
Rheology is the study of the flow and deformation properties of the matter.
Viscosity:
The viscosity of a fluid is its resistance to flow or movement.
According to flow, fluids are of two types. They are:-
1. Newtonian Fluids &
2. Non- Newtonian Fluids.
1. Newtonian Fluids:- Liquids which follow Newton’s law of viscous flow are known as newtonian’s liquids.
2. Non-Newtonian Fluids:- Liquids which do not follow Newton’s law are known as non-newtonian fluids.
Example: Colloidal dispersion, emulsions, suspensions and ointments.
Shearing Stress:
The force per unit area F/A required to bring about flow is called the “Shearing Stress”
· The flow properties of Non-Newtonian Materials are three types. They are:-
1. Plastic flow
2. Pseudo plastic flow
3. Dilatants flow.
Dispersed System:
A dispersed system is defined as a system in which one phase, the dispersed phase, is distributed uniformly as particles throughout another phase, called the sispersion medium or continuous phase.
Colloidal Dispersion:
If the particles have a size ranging from 1 nm to 1 µm, which is dispersed in the continuous phase, this system is called colloidal dispersion.
Colloids:
The particles have a size ranging from 1 nm to 1 µm is called colloids.
Because of their large surface area, colloids show greater efficiency for absorption or adsorption. |
Coarse Dispersion:
The size of the dispersed particles ranging from 1 µm to 100 µm, which is dispersed in the continuous phase, this system is called coarse dispersion.
