An Introduction to Rheology

1. Introduction. What is rheology? Historical perspective. The importance of non-linearity. Solids and liquids. Rheology is a difficult subject. Components of rheological research. 2. Viscosity. Practical ranges of variables which affect viscosity. The shear-dependent viscosity of non-Newtonian liquids. Viscometers for measuring shear viscosity. 3. Linear Viscoelasticity. The meaning and consequences of linearity. The Kelvin and Maxwell models. The Relaxation Spectrum. Oscillatory shear. Relationships between functions of linear viscoelasticity. Methods of measurement. 4. Normal Stresses. The nature and origin of normal stresses. Typical behaviour of N1 and N2. Observable consequences of N1 and N2. Methods of measuring N1 and N2. Relationships between viscometric functions and linear viscoelastic functions. 5. Extensional Viscosity. Importance of extensional flow. Theoretical considerations. Experimental methods. Experimental results. Some demonstrations of high extensional viscosity behaviour. 6. Rheology of Polymeric Liquids. General behaviour. Effect of temperature on polymer rheology. Effect of molecular weight on polymer rheology. Effect of concentration on the rheology of polymer solutions. Polymer gels. Liquid crystal polymers. Molecular theories. The method of reduced variables. Empirical relations between rheological functions. Practical applications. 7. Rheology of Suspensions. The viscosity of suspensions of solid particles in Newtonian liquids. The colloidal contribution to viscosity. Viscoelastic properties of suspensions. Suspensions of deformable particles. The interaction of suspended particles with polymer molecules also present in the continuous phase. Computer simulation studies of suspension rheology. 8. Theoretical Rheology. Basic principles of continuum mechanics. Successful applications of the formulation principles. Some general constitutive equations. Constitutive equations for restricted classes of flows. Simple constitutive equations of