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Size & Shapes of Colloidal Particles range from 1–1000 nm, influencing stability and optical properties. Size & Shapes of Colloidal Particles include spherical, rod-like, lamellar, and irregular forms. Size of Colloidal Particles: Range: 1 nm to 1000 nm (i.e., 10⁻⁹ m to 10⁻⁶ m). Size influences: Surface area Stability Interaction with biological membranes Drug release … Read more

Effect of Temperature on Viscosity is key in drug formulation, lubrication, and industrial processes. Effect of Temperature on Viscosity shows liquids thin as heat rises and molecules move faster. Viscosity is inversely related to temperature – as temperature increases, viscosity usually decreases. Why? At higher temperatures, the kinetic energy of molecules increases. This reduces intermolecular … Read more

Definition of Kinematic Viscosity: Kinematic viscosity is the ratio of dynamic viscosity to the density of the fluid. $\nu = \frac{\eta}{\rho}$ Where: ν = kinematic viscosity (units: m²/s or centistokes, cSt) η = dynamic viscosity (e.g., poise, centipoise) ρ = density of the fluid (e.g., g/cm³) Why is it important? It relates viscosity to the … Read more

Law of Flow (Newton’s Law of Viscosity) states shear stress is directly proportional to velocity gradient. Law of Flow (Newton’s Law of Viscosity) explains Newtonian fluid behavior in pharmaceutical systems. This refers to the application of Newton’s law in describing fluid behavior. Newton’s Law (Restated): $\frac{F}{A} = \eta \cdot \frac{du}{dy}$ Where: F/A = applied force … Read more

Newtonian Systems show constant viscosity, independent of applied shear rate. Newtonian Systems is a fluid whose flow behavior follows Newton’s law of viscosity, which means: The viscosity remains constant regardless of the shear rate or the force applied. The relationship between shear stress (F/A) and shear rate (du/dx) is linear. Definition: A Newtonian fluid is … Read more

Rheology is the science of flow and deformation of matter, especially liquids and semisolids. In physical pharmaceutics, understanding rheology is crucial for: Designing liquid formulations (e.g., syrups, emulsions, suspensions), Semi-solids (e.g., creams, ointments, gels), And ensuring proper processing, mixing, filling, and dispensing of products. Rheology is important for: Processing (pumping, mixing, filling bottles) Product performance … Read more