Rheology of Materials
Code
7436
Academic unit
Faculdade de Ciências e Tecnologia
Department
Departamento de Ciências dos Materiais
Credits
6.0
Teacher in charge
Maria Teresa Varanda Cidade
Weekly hours
5
Total hours
84
Teaching language
Português
Objectives
Know | To distinguish between newtonean and non-newtonean fluids |
| To recognize the importance of fluid viscoleasticity and the way it influences fluid deformation under shear and elongation |
| To recognize the importance of non-zero normal stress differences in the viscoelastic materials and the way they may influences the rheological behavior and processing |
| To recognize the importance of extensional viscosity and the way it may affect the flow and processing of viscoelastic fluids |
| To understand the parameters that influence the rheological functions of polymers |
| | To understand the rheological behavior of multiphasic systems (suspensions, emulsions, polymer blends, etc) |
| | To understand the rheology of other materials and products (cosmetics, food, paints, glues, etc) |
| Perform | To measure rheological properties of polymers and other materials and products, by resorting to appropriate equipments (viscosimeters and rheometers) |
| To determine rheological functions measured in different geometries |
| To fit the experimental results to appropriate models and extract relevant information from it |
| To apply the understanding of the rheological behavior of a certain fluid to their processing conditions |
| Soft Skils | Work planning and organization |
| Application of prior knowledge, time management and schedule-keeping |
| Initiative and problem solving |
| Communication ability |
| Self-demanding posture, quality concern |
Subject matter
Chapter 1. Introduction: The concept of rheology and the importance of its study. Fundamentals of rheology: flow geometry, Hooke’s law, Newton’s law, equations of motion, equations of Navier Stokes.Viscoelasticity: the concept of viscoelasticity, viscoelastic solids and liquids. Deborah number.Classification of the fluids: newtonean fluids and non-newtonean fluids (shear thinning, shear thickening, etc). Chapter 2. Rheological functions of non-newtonean fluids. Viscosity: Flow curves, constitutive equations and models that describe the behavior of non-newtonean fluids. Normal stress differences: origin, first normal stress difference as a measure of the elasticity of a fluid, consequences of the existence of non-zero normal stress differences. Linear viscoelasticity: behavior of viscoelastic fluidos under linear viscoelastic regime: complex viscosidade, storage modulus and loss modulus.Extensional viscosity: types of extensional deformation, importance of the extensional flows, relationships between rheologic functions under shear and extensional flow. Chapter 3. Measuring devices of rheologic functions.
Simple apparatus for routine control.Rotational rheometersCapillary rheometers.Extensional rheometers. Chapter 4. Polymer rheology: factors that affect the rheological properties of polymers Effect of temperature. Master curves.Effect of pressure. Effect of molecular weight and its distribution.
Effect of molecular structure: effect of the ramifications, effect of other structural factors.Effect of the presence of additives. Effect of the addition of solvents: rheology of polymeric solutions; viscosity as a function of concentration, dependence of the viscosity of polymeric solutions with temperature and the shear rate, dynamic rheological properties of polymeric solutions. Chapter 5. Rheology of liquid crystalline polymers (LCP’s): Introduction: notion of liquid crystals and liquid crystal polymers.
Rheology of lyotropic liquid crystalline polymers: viscosity in function of concentration, viscosity and normal stress differences in function of shear rate, influence of temperature, concentration and mean molecular weight of the polymer in the rheological functions of lyotropic solutions. Rheology of thermotropic liquid crystalline polymers: viscosity and normal stress differences in function of shear rate, influence of temperature and mean molecular weight of the polymer in the rheological functions of thermotropic LCP’s. Models applicable to the rheological behavior of LCP’s.
Chapter 6. Rheology of multiphasic polymeric systems: Reology of suspensions: diluted suspensions, concentrated suspensions.Reology of emulsions.Rheology of fibre reinforced polymers. Rheology of polymer blends. Case of the rheology of thermoplastics/LCP’s blendsRheology of block copolymers. Chapter 7. Food Rheology Introduction: the importance of rheology in food industry. Types of rheological measurements: fundamental measurements, empirical measurements and imitative measurements. Fundamental measurements: rheological characterization of the behavior of food products, rheology of polysaccharide solutions and proteins.
Types of empirical measurements and imitative measurements. The importance of the glassy state on food.
Chapter 8. Rheology of pharmaceutical products and cosmetics. Introduction: the importance of rheology on the medicinal industry and in cosmetics Newtonean and non-newtonean fluids. The concepts of consistency, extensibility and lubricity. Types of behaviors observed in pharmaceutical products and in cosmetics: plastic, shear thinning, shear thickening, tixotropic. Rheograms and flow curves.Viscoelasticity. Oscillatory measurements.Some examples of “rheological modifiers” of the formulations. Rheological changes, aging and biocaducity.Rheological characteristics as a measure of medicine liberation. Chapter 9. Paint rheology Importance of the rheology in paint industry. Tixotropy and time for the recuperation of viscosity.Factors that influence the rheology of a paint: nature of the binder, composition of the solvent, concentration of the binder, pigment content, temperature.Relationship between the shear rate and the properties of paints: sagging, settling, painting, etc.Use of rheological modifier additives. Relationship between the paint rheology and the paint application method.
Chapter 11. Rheology of cementicious materials and hidraulic grouts. The importance of rheology in building industry. Yield stress, plastic viscosity. Its dependence on shear rate, temperature, concentration of the mixture. Rheological models for these materials
Bibliography
[1] H.A. Barnes, J.F. Hutton and K. Walters, “An Introduction to Rheology”, Elsevier Publishers, 1989.
[2] R.B. Bird, R.C. Armstrong and O. Hassager, “Dynamics of Polymeric Liquids: Volume II, Fluid Mechanics”, John Wiley & Sons Inc., 1977.
[3] L.E. Nielsen, “Polymer Rheology”, Marcel Dekker, Inc., 1977.
[4] A.W. Birley, B. Haworth and J. Batchelor, “Physics of Plastics: Processing, Properties and Materials Engineering”, Hanser Publishers, 1991.
[5] G.V. Vinogradov and A.Ya. Malkin, “Rheology of Polymers”, Mir Publishers, 1980.
[6] C.L. Rohn, “Analytical Polymer Rheology: structure – processing – property relationships”, Hanser Publishers, 1995.
[7] R.G. Larson, “The Structure and Rheology of Complex Fluids”, OxfordUniversity Press, 1999.
[8] “Reologia e suas Aplicações Industriais”, A. Gomes de Castro, J.A. Covas and A. Correia Diogo (Eds), Ciência e Técnica (Instituto Piaget), 2001.
[9] “NL Rheology Handbook”, NL Industries, Inc..
[10] “Paints, Coatings and Solvents”, D. Stoye and W. Freitag (Eds), Wiley – VCH, 2001.
[11] “Introduction to Paint Chemistry and principles of paint technology”, J. Bentley and G.P. Turner, Chapman & Hall, 2000.
Teaching method
The couse is given with theoretical, problem resolution and laboratories classes.
In the theoretic classes slides and data-show will be used.
In the problem resolution classes, students are invited to, previously, solve a certain number of problems of a list of problems given in the beggining of the course, the classes serving, essentially, to clarify any doubts concerning the students resolution. By the end of the class all the resolutions will be writen in the blackboard, which will be done by the students, whenever it is possible.
In the laboratory classes each group will perform part of a work that appears in the script. The complete data, obtained by all the groups, will be given to the students, in order that they can perform calculations, extract conclusions, etc
Evaluation method
The evaluation of the lab. sessions will be performed through an individual questionnaire, that will be performed one or two weeks after the corresponding lab. session.
The classification of the laboratory (NL) will be determined with the following equation:
NL = 0.8 Nq + 0.2 Nc (1)
with
Nq - classification of the questionnaire
Nc- classification of the work performed, extra class, by the student, according to what is asked for in the script (data modelisation, activation energy determination, etc).
The final classification (NF) of the course will be determined with the following equation:
NF = 0.6 NT + 0.2 NL + 0.2 Ni (2)
with
NT - average value of the classification of two tests performed during the semester, or classification of the final examination
Ni - classification given by the participation of the student in the problem resolution lessons, that will take into account not only the individual, previous, resolution of the problems, but also the number of assisted lessons and the participation during the lessons itself.
Students may be released of the examination if they have obtained NF higher or equal to 9.5 val, with a minimum of 8 val in each test, and with NT higher than 9.0 val.
Students that have not obtained aproval with the tests, may perform a final examination, as long as they have (NL + Ni)/2 equal or higher than 9.5 val.
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