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
Introduction to Colloidal Dispersions explains systems with particles sized 1–1000 nm dispersed in a medium. Introduction to Colloidal Dispersions highlights applications in pharmacy, food, cosmetics, and medicine. Colloidal Dispersions is a biphasic system where very small particles (1–1000 nm) of one substance (dispersed phase) are evenly distributed throughout another (dispersion medium). It bridges the gap … Read more
Protective Action of Colloids prevents coagulation by stabilizing dispersed particles. It is vital in pharmaceuticals, food, and industrial formulations. Definition: The ability of lyophilic colloids to protect lyophobic colloids from coagulation by electrolytes. Mechanism: Lyophilic colloids form a protective layer around lyophobic particles, preventing them from aggregating. Protective Colloid: A lyophilic colloid (such as gelatin … Read more
Definition of Peptization: Peptization is the Process of converting a precipitate into colloidal dispersion by adding a peptizing agent (usually an electrolyte or surfactant). Mechanism of Peptization: Peptizing agent imparts electrical charge to the precipitate particles. This causes repulsion, breaking them into colloidal size. Example: Fe(OH)₃ precipitate + FeCl₃ → Fe(OH)₃ colloid. Use in Pharma: … Read more
Coacervation is the separation of colloids into two liquid phases, rich and poor in dispersed particles. It is used in microencapsulation, pharmaceuticals, and controlled drug delivery systems. Definition of Coacervation: A phase separation process where colloids separate into two liquid phases: Dispersed phase (coacervate) – rich in colloidal material Equilibrium phase – depleted in colloid … Read more
Effect of Electrolytes on Colloidal Stability explains how ions alter charge, causing coagulation or stability. Effect of Electrolytes on Colloidal Stability is key in pharmaceuticals, water treatment, and food systems. Electrolytes play a crucial role in determining colloidal stability by influencing the surface charge and electric double layer surrounding colloidal particles. 1. Coagulation and Double … Read more
Electrical Properties of Colloids explain charge, electrophoresis, and electro-osmosis in dispersions. Colloidal particles typically carry a surface charge when dispersed in a medium. Electrical Properties of Colloids determine stability and behavior of colloidal systems. This charge influences their stability, interactions, and movement under electric fields. The key electrical properties include: 1. Electric Double Layer Colloidal … Read more
Comparative Account of General Properties of Colloids explains optical, electrical, and mechanical behaviors. Comparative Account of General Properties of Colloids highlights differences between lyophilic and lyophobic sols. Property Lyophilic Colloids Lyophobic Colloids Association Colloids (Micelles) Affinity for Medium Strong Very weak or none Amphiphilic (both water-loving and -hating parts) Ease of Formation Easily formed by … Read more
Classification of Colloids is based on phase systems like sols, gels, emulsions, and foams. Classification of Colloids depends on physical state, interaction, and nature of dispersed phase. Colloids can be classified in several ways: Based on the Physical State of Dispersed and Dispersion Phase: Dispersed Phase Dispersion Medium Name Example Solid Solid Solid sol Colored … Read more
