PPH 102 - Lecture 1.docx

PHYSICAL PHARMACY PPH102 SPRING 2025 CHAPTER 1: RHEOLOGY =================== - Define the rheology, know the rheological behavior of fluid pharmaceutical dosage forms. - Understand the application of rheology in the pharmaceutical science and clinical pharmacy....

PHYSICAL PHARMACY PPH102 SPRING 2025 CHAPTER 1: RHEOLOGY =================== - Define the rheology, know the rheological behavior of fluid pharmaceutical dosage forms. - Understand the application of rheology in the pharmaceutical science and clinical pharmacy. - Recognize the difference between a lot of rheological terms such as: shear stress and shear rate, fluidity and viscosity, shear thinning and shear thickening, flow and deformation, plastic, pseudo-plastic, and dilatant flow, rheology and rheogram, thixotropy and anti-thixotropy. CHAPTER 1: RHEOLOGY =================== - Realize the difference between Newtonian and Non-Newtonian fluids according to understanding of Newton\'s law. - Ability for the practical determination of rheologic properties with different types of viscometers. LECTURE 1 QUESTION ================== 1. **Please, mention the unit of viscosity** 2. **Mention the viscosity of water** CHAPTER 1: RHEOLOGY =================== - **Rheology:** It is the branch of physical pharmacy science that deals with flow of liquids and deformation of semisolids. - Origin of the word: the term **"rheology**," is a Greek term that was divided in to two parts. The first part: (**rheo**) which means **(to flow**) and (**logo**s) that means (**science**). - Rheology cab be applied for gases, liquids, and semi-solids. - Solids are completely resistant to flow and deformation. CHAPTER 1: RHEOLOGY =================== - **Viscosity:** means the resistance of a fluid to flow. - **Fluidity:** ability of liquids to flow. - Therefore, greater resistance to follow will be expressed as higher viscosity. - Example: flow of tape water, glycerin, and honey on a glass surface. - Honey and glycerin will show lower flow and lower dispersion on the surface of the glass. On the other hand, tape water will flow easily CHAPTER 1: RHEOLOGY =================== CHAPTER 1: RHEOLOGY ------------------- - Paints - Inks - road-building materials - dairy products. CHAPTER 1: RHEOLOGY =================== - solutions, suspensions, emulsions, cosmetics products both dilute and concentrated colloidal systems. - Formulation and analysis of such pharmaceutical products as pastes, suppositories, and tablet coatings. - Manufacturers of medicinal and cosmetic creams, pastes, and lotions CHAPTER 1: RHEOLOGY ------------------- - Mixing and flow of materials (Dosage form) - Packaging into containers (Product) - Pouring of liquids from a bottle (Application/Administration) - Extrusion of ointments and creams from a tube - Passage of liquid from ampoule through a syringe needle. ### NEWTONIAN AND NON-NEWTONIAN SYSTEMS 1. Newtonian 2. Non-Newtonian systems. #### Newtonian systems - If we have a block of liquid that consists of parallel plates, such as a pack of cards. - Consider a **force F' (dyne)** was applied to the surface layer with **area A** - to give a difference from the bottom layer with **distance (dr, cm) and velocity (dv, cm/sec).** - Each layer will move with a velocity which is directly proportional to its distance from the bottom layer. #### Newtonian systems - The force applied per unit area form the liquid to produce liquid flow, was called **shearing stress (F).** - Shearing stress: the force F\' applied per unit are A to cause flow. ##### Newtonian systems - - - - - - - - - - - - - - ##### Newtonian systems - **Fluidity φ**: it is a term that represent the reciprocal of the fluidity in the meaning and value φ = 1/ η - According to the previous laws, Newton divided the liquids into two main classes: - Newtonian - Non-Newtonian systems. ##### E:\\Mohamed\\courses\\1st yr\\Physical pharmacy\\images and videos\\neowtnian viscosity.png Newtonian systems  ##### E:\\Mohamed\\courses\\1st yr\\Physical pharmacy\\images and videos\\neowtnian viscosity.png Newtonian systems - The previous plot exhibits that the shearing rate G is directly proportional to the shearing stress F, and starts from point of origin. - The slope of this relation equal G/F, which equal fluidity φ of the liquid and reciprocal of the viscosity 1/η. #####  Newtonian systems - The slope of this curve at any point is a **[constant]** value that represents the value of viscosity **[(dynamic viscosity) η.]** - So, single determination of viscosity from the shear stress at any given shear rate is sufficient to determine the flow properties of the سؤااااااااااااااااااااااااااال)Newtonian liquids ####  Newtonian systems - This graph is called **Rheogram** which defined as the graph that shows the rheological properties of liquids by representing the variation of shearing rate G with the change of the applied shearing stress F. - The relation between shear rate G and viscosity η will be constant Examples for Newtonian liquids: - Water, Glycerin - Chloroform, Ethanol - Olive oil, Castor oil Diluted suspension.  gu.edu.eg