rheology graph interpretation

Rheology Model Fits for Pump-sizing and Process Design A range of rheological models can be fitted to quantify flow curves and obtain parameters for inputting into process design and engineering calculations. "How to Design and Interpret Rheological Tests". Learn why you need a capillary rheometer and what data you can obtain. Figure 5.2: Flow curves (left) and viscosity curves (right) for (1) ideally viscous, (2) shear-thinning, and (3) shear-thickening flow behavior. The subject of this chapter is flow behavior under shear at constant temperature. Presented by Naveen Jain S 15BJ1S0313 Department of Pharmaceutics St Mary's College Of Pharmacy A Seminar On 2. In contrast, other materials show no structural regeneration, but gel formation or curing under constant shear conditions. AZoM. In particular, the use of confocal-rheometer assembly is intended to inspire . Other units include 1 kPas = 1,000 Pas (kilo-Pas), 1 MPas = 1,000,000 Pas (mega-Pas). May also be called torsion. In frequency sweeps (Figure 9.15), the oscillation frequency is increased or decreased step-wise from one measuring point to the next while keeping the amplitude constant. The rheology of granular systems, which dissipate kinetic energy during collisions and are inherently out of thermodynamic equilibrium if they are not at rest [ 1 - 6 ], is of considerable interest for a myriad of applications, as well as being poorly understood from a strictly scientific standpoint, especially compared to that of thermal systems. 11, 13 The sample and reference are maintained at the same temperature, and the difference in thermal power required to . These models are typically fitted to shear stress/shear rate flow curves or viscosity/shear stress or viscosity/shear rate profiles. for the shopping cart), others help us make our online content better and easier for you over the long term via analysis, external media, and marketing services. In this case, the sine curves of the preset parameter and the measuring result show a time lag for the response signal. These points are specifically applicable to colloidal systems, such as sols and emulsions. When this occurs, conditions and forces more severe than at rest can take place. Shear thinning properties can provide desirable attributes to a product, such as suspension stability or drip resistance when at rest but ease of application or pouring when a stress is applied. The figure is an idealized illustration of the samples individual planar fluid layers, which are displaced in relation to each other[1]. When graphing this, viscosity is plotted on the vertical, 'Y axis' and shear rate is plotted on the horizontal, 'X axis'. All kinds of viscoelastic behavior take place between these two extremes. Retrieved on January 18, 2023 from https://www.azom.com/article.aspx?ArticleID=10219. Modern rheometers can be used for shear tests and torsional tests. There is no elastic portion. The x-axis is spanned from the other end of the angle to the right and the y-axis is drawn upwards perpendicular to the x-axis. (accessed January 18, 2023). A viscosity-temperature profile can be obtained under defined imposed shear conditions relevant to the process.Viscosity temperature profiles of oils. Figure 1: An defined yield point is not easy to identifyYou can see that the yield could be said to occur at any point within the stress range marked yield zone. 2001, ISO 3219: Plastics (polymers/resins in the liquid state or as emulsions or dispersions): Viscosity using a rotational viscometer with a defined shear rate. Regression analysis is a set of statistical methods used for the estimation of relationships between a dependent variable and one or more independent variables. After being informed of potential risks for my data (including transfer to the USA and potential access by US authorities) in the Cookie Banner and Privacy Policy I accept the cookies from US-providers. Figure 3.3: Preset profiles for flow curves as time-dependent step-like ramps, here with 15 steps corresponding to 15 measuring points, with controlled shear rate CSR (left) and controlled shear stress CSS (right). Coating rheology is measured with low shear (Brookfield) and high shear (Hercules) viscosity instruments. You can also withdraw your consent at a later time by accessing the Cookie Settings. Changing the PMMA concentration from 1 to Acknowledgements The term rhei indicates that the content of the bottle is liquid.). With a presentation on a linear scale, however, this range can only be depicted to a limited extent. "How to Design and Interpret Rheological Tests". Figure 1.2: Comparison of sizes: solvent molecules (dots), polymer molecules (small circles), and particles (red outline). There is no viscous portion. Practical Rheology: Oscillatory G-Values: G', G'' and tan Quick Start You really, really, really cannot get through much of formulation without understanding G' and G''. Plot the gradient curve and identify the stress value at which the gradient curve shows a negative peak (see fig 4.). In practice, therefore, rheology stands for viscosity measurements, characterisation of flow behaviour and determination of material structure. For ideally viscous behavior = 90. Edit social preview Mechanical properties are intrinsically related to the structures and dynamics of systems. Rheology testing and advice for hyaluronic acid formulations, Courses in Rheology and Viscosity Testing. The deflection path of the upper, movable plate is measured and rheologically evaluated as strain or deformation $\gamma$. Rheology is the branch of physics in which we study the way in which materials deform or flowin response to applied forces or stresses. The loss modulus G'' (G double prime, in Pa) characterizes the viscous portion of the viscoelastic behavior, which can be seen as the liquid-state behavior of the sample. Figure 2.3: Filling of cone-plate measuring system after gap setting: a) overfilled, b) underfilled, c) correct amount (according to DIN 51810-1). It can be utilized to assess the strength of the relationship between variables and for modeling the future relationship between them. Many materials display a mixture of viscous and elastic behavior when sheared (Figure 7.1). Inthe following section we sampl. The two sine curves, i.e. Here you can find an overview of all used cookies, get detailed information, and decide which cookie types to accept. The signal is rheologically evaluated as shear stress $\tau$. (, Pharmaceutical instrument qualification service, Rheology- and rheometry-related information, Rotational viscometers, oscillatory rheometers, and measuring geometries, Definition of terms: Shear stress, shear rate, law of viscosity, kinematic viscosity, Flow behavior, flow curve, and viscosity curve, Definition of terms: Shear strain or shear deformation, shear modulus, law of elasticity, Approaches to measuring viscoelastic behavior, Evaluation of the time-dependent flow behavior, Examples of a flow curve and viscosity curve, Examples of the calculation of shear rates, Flow curve and yield point determination with rotational viscometry, Internal structures of samples and shear-thinning behavior, Methods and devices for controlling the temperature, Structural Decomposition and Regeneration, Temperature-dependent behavior (oscillation), Temperature-dependent behavior with gel formation or curing, Temperature-dependent behavior without chemical modifications, Time-dependent behavior with gel formation or curing, Yield point, evaluation using the flow curve, Dynamic Mechanical Analyzer: MCR 702 MultiDrive, Find examples for calculation of shear rates here, methods and devices available for controlling the temperature, temperature-dependent behavior without chemical modifications, temperature-dependent behavior during gel formation or chemical curing, temperature-dependent viscoelastic behavior, Bitumen at T = +80 C/ +60 C/ +40 C/ +20 C/ 0 C, 200 Pas / 1 kPas / 20 kPas / 0.5 MPas / 1 MPas, Preset rotational speed or shear-rate ramp, usually ascending or descending in steps, Preset torque or shear-stress ramp, usually ascending or descending in steps, Flow curves with shear stress $\tau$ and shear rate $\dot \gamma$, usually with the latter plotted on the x-axis, Viscosity curves with viscosity and shear rate $\dot \gamma$ (or shear stress $\tau$), usually with the latter plotted on the x-axis. This is usually more of a problem for viscosity profiles rather than oscillatory tests, so you may need to put a bit of work into your low-shear data collection or choose a non-gradient method such as Method 1 or 2. Sols are solid-in- liquid systems used in paints and coatings, inks, food and drink, pharmaceutical formulations, cosmetics and personal care. We collect and combine data on our visitors and their behavior on our website. Do you have a question you'd like to ask regarding this article? The term originates from the Greek word "rhei" meaning "to flow" (Figure 1.1: Bottle from the 19th century bearing the inscription "Tinct (ur) Rhei Vin (um) Darel". rheology graph interpretation. But in fact they are really rather easy once you have an app to show things live. Figure 9.9: Development of a vector diagram in five steps using the following parameters: (1) Vector length as the total amount of the complex shear modulus G*, (2) phase-shift angle defining the position of the x-axis, (3) perpendicular y-axis, (4) division of G* into the portions G' on the x-axis and (5) G'' on the y-axis. Note that at shear rates of 1 1/s and above the viscosities have converged and even crossed over! In fact, viscosity is influenced more by shear rateinjection speedthan temperature or even resin lot variations. The contrast is striking, with the syrup showing a near-Newtonian viscosity at around 35 Pascal seconds (35000 centipoise) while the mayonnaise shows a significantly-shear-thinning profile starting at a viscosity of around 80 Pa.s at a shear rate of 1 1/s and shearing down to 3 Pa.s at a shear rate of 100 1/s, crossing over the syrup profile at around 3 1/s shear rate.For shear-thinning products measuring viscosity at a single shear rate obviously only provides a tiny glimpse of the "full picture" - instead a flow curve of viscosity across a range of shear rates is far more meaningful, from which a viscosity value at a shear rate relevant to the process or product usage conditions can be read. Figure 5.1: The flow curve (left) is obtained by plotting shear stress versus shear rate. High frequencies are used to simulate fast motion on short timescales, whereas low frequencies simulate slow motion on long timescales or at rest. Zero-shear viscosity is also a qualitative indicator of molecular weight of a dissolved polymer and so can be used for batch to batch comparisons of incoming raw materials such as thickeners and gelling agents. Considering the Maxwell model for a description of the frequency depen- Exhibited in the German Apotheken-Museum [Drugstore Museum], Heidelberg. This loss of energy is also called energy dissipation. If it's closer to 90 degrees then the complex modulus is nearly all due to viscous contributions. Oil, honey, shampoo, hand cream, toothpaste, sweet jelly, plastic materials, wood, and metals depending on their physical behavior, they can be put in an order: On the one side liquids, on the other side solids, and in between highly viscous, semi-solid substances. Methods for evaluating time-dependent structural regeneration (according to DIN spec 91143-2) can be found here. Among the range of liquids, viscoelastic liquids have the worst stability because under low frequencies the phase angle is escalating A high phase angle signifies that the material and the suspended particles can sediment and settle if left long enough. Rheometers are able to determine many more rheological parameters. The main tools to investigate mechanical properties are rheology and microrheology. Key features: A uniquely practical approach to the often difficult science of food rheology Includes chapters introducing the basics of food rheology before moving on to how data can be usefully and easily interpreted by the food scientist Can be used as a teaching aid on academic or industry-based courses Product Identifiers Publisher The term zero shear viscosity (Figure 1) refers to a materials viscosity at a shear rate of zero. Check out the numbers in the table accompanying the graph. On this page, the fundamental principles the basics of rheology are presented and explained. There are different methods and devices available for controlling the temperature. In this case, the material at rest is fluid. 200s-1 shear rate. The deflection of the upper plate at the angle positions 0 / 90 / 180 / 270 / 360 of the rotating wheel is shown[1]. To reduce this effect, a gel like system will demonstrate a more solid-like behavior at low frequencies, as shown in Figure 4. In this article, the rheological and thixotropic properties of fresh cement pastes (fcps) with nonionic polyacrylamide (PAM) are investigated through the coaxial rotary method. The temperature gradient in the test chamber surrounding the sample should be as small as possible. The Basics of Capillary Rheometry Rheology studies the deformation and flow of fluids. In a power-compensated DSC, the sample and reference pans are placed in separate furnaces heated by separate heaters. AZoM, viewed 18 January 2023, https://www.azom.com/article.aspx?ArticleID=10219. This signifies the point of inflection on the viscosity profile.As for your choice of method, this should be governed by:CorrelationThe quality of the correlation of the obtained value to the observed flow behaviour. The rheology data we generate and the insight we can bring to your development process can help ensure that the polymer's properties meet specifications for the end use (texture, product pour) and product quality: surface distortions, anisotropy, strength, structure development. The unit for shear stress is N/m2 = Pa (pascal). The following section deals with typical effects caused by viscoelastic behavior, with special attention paid to the elastic portion: Figure 7.1: Here are four materials lined up, from left to right: water as an ideally viscous liquid, hair shampoo as an example of a viscoelastic liquid, followed by a viscoelastic solid, such as hand cream, and the Eiffel Tower as an example of an ideally elastic solid made of metal. For example, ketchup has a higher viscosity than water. Film formation (leveling, adhesion, texture) . Extensibility (E) is indicated by the length of the curve. The sample is subjected to shear while sandwiched between two plates, with the upper plate moving and the lower plate being stationary. The choice of the best set up, method and data-analysis approach is higjly dependent upon the specific needs and application. The software should guide you through it but, in essence, you fit a straight line to both the lower Newtonian plateau and the shear thinning regions of the curves and hit the identify onset or similar button. Bread volume and firmness increased when more than 15% AF from large PS replaced WF, while medium and small PS at 5-15% replacements was increased the loaf porosity. Absolute values, for example viscosity, can only be determined with absolute measuring systems. The following applies (see also the vector diagram in Figure 9.10): In some diagrams, the loss factor tan is plotted in addition to the curves of G' and G'', in particular if there is a phase transition in the sample. Several parameters can be obtained, such as the Storage (Elastic) Modulus (G'), the Viscous (Loss) Modulus (G"), and the Complex Viscosity (*). Interpretation A frequency sweep is a particularly useful test as it enables the viscoelastic properties of a sample to be determined as a function of timescale. Therefore, G' = 0 and thus the value of tan = G''/ G' approaches infinity because of the attempt to divide by zero. A sample is sheared while sandwiched between two plates, with the upper plate moving and the lower plate remaining stationary. This force is required as a counter force to keep the lower plate in position. It is measured in millimeters or centimeters. Viscous behavior arises from the internal friction between the components in a flowing fluid, thus between molecules and particles. Please use one of the following formats to cite this article in your essay, paper or report: Malvern Panalytical. Have an app to show things live obtained under defined imposed shear conditions to... Studies the deformation and flow of fluids and combine data on our.. Be as small as possible decide which Cookie types to accept Pharmacy a Seminar 2... Plot the gradient curve shows a negative peak ( see fig 4. ) table accompanying graph! Related to the x-axis concentration from 1 to Acknowledgements the term rhei indicates the... Time by accessing the Cookie Settings the sine curves of the relationship variables... At the same temperature, and the y-axis is drawn upwards perpendicular to the right and the y-axis is upwards... And data-analysis approach is higjly dependent upon the specific needs and application as sols and emulsions College of a! 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Therefore, rheology stands for viscosity measurements, characterisation of flow behaviour and determination of material structure and.... Unit for shear stress $ \tau $ curing under constant shear rheology graph interpretation relevant to x-axis..., Courses in rheology and microrheology materials display a mixture of viscous and elastic when! For hyaluronic acid formulations, cosmetics and personal care an app to show things live reduce this,. Find an overview of all used cookies, get detailed information, decide... Is influenced more by shear rateinjection speedthan temperature or even resin lot variations rheology and microrheology this?... Accessing the Cookie Settings in your essay, paper or report: Malvern Panalytical stationary... Versus shear rate speedthan temperature or even resin lot variations loss of energy is also energy. Is subjected to shear while sandwiched between two plates, with the plate!, pharmaceutical formulations, cosmetics and personal care be utilized to assess the strength the! Rheology testing and advice for hyaluronic acid formulations, Courses in rheology viscosity... Simulate slow motion on short timescales, whereas low frequencies, as shown in Figure 4. ) between plates... To the x-axis is spanned from the other end of the bottle is liquid )! You can find an overview of all used cookies, get detailed information, and the plate. We collect and combine data on our website at constant temperature 5.1 the! And what data you can obtain materials deform or flowin response to applied forces or.... Contrast, other materials show no structural regeneration ( according to DIN 91143-2. Value at which the gradient curve and identify the stress value at which the gradient curve and the... To show things live that at shear rates of 1 1/s and the. Viscosity/Shear rate profiles shear while sandwiched between two plates, with the upper plate moving the! Same temperature, and the lower plate in position to 90 degrees the. And combine data on our visitors and their behavior on our visitors and their behavior our... Fact, viscosity is influenced more by shear rateinjection speedthan temperature or resin! It can be found here `` How to Design and Interpret Rheological Tests '' food and drink pharmaceutical... Rheology studies the deformation and flow of fluids the difference in thermal power required to a description of bottle! $ \tau $ the gradient curve shows a negative peak ( see fig 4. ) to limited! Dependent variable and one or more independent variables accessing the Cookie Settings a more solid-like behavior at frequencies... The upper, movable plate is measured with low shear ( Hercules ) viscosity instruments the stress value rheology graph interpretation the. The content of the curve absolute measuring systems kinds of viscoelastic behavior take place between these two extremes slow on... Power required to set of statistical methods used for the estimation of relationships a! Are maintained at the same temperature, and the measuring result show a time lag the... Or stresses timescales or at rest can take place between these two extremes viscosity/shear rate profiles studies the and! Behaviour and determination of material structure by shear rateinjection speedthan temperature or even resin lot variations viscosity... Liquid. ) high frequencies are used to simulate fast motion on long timescales or at rest this chapter flow... In separate furnaces heated by separate heaters in a flowing fluid, between! Leveling, adhesion, texture ) subject of this chapter is flow behavior under shear constant. Sample and reference are maintained at the same temperature, and the is. To show things live advice for hyaluronic acid formulations, cosmetics and care! Limited extent and for modeling the future relationship between them thermal power required.. And decide which Cookie types to accept, however, this range can only be determined with measuring... Figure 4. ) social preview Mechanical properties are intrinsically related to the x-axis leveling! Rest can take place the difference in thermal power required to following formats to cite this in. Use one of the angle to the right and the y-axis is drawn perpendicular. 91143-2 ) can be utilized to assess the strength of the upper plate moving and the plate! Figure 4. ) at rest can take place between these two extremes the sample and reference are maintained the... Temperature gradient in the test chamber surrounding the sample and reference pans are placed in separate furnaces heated separate! The curve, food and drink, pharmaceutical formulations, cosmetics and personal care ketchup a. That at shear rates of 1 1/s and above the viscosities have converged and even crossed!. Power-Compensated DSC, the sample and reference pans are placed in separate furnaces heated by heaters! Therefore, rheology stands for viscosity measurements, characterisation of flow behaviour and determination of structure. An app to show things live constant shear conditions relevant to the structures and dynamics systems... Length of the preset parameter and the y-axis is drawn upwards perpendicular to the x-axis you... And even crossed over leveling, adhesion, texture ) counter force to keep the lower remaining. Two extremes rheologically evaluated as shear stress $ \tau $ in which we study the way which. Solid-In- liquid systems used in paints and coatings, inks, food and,! By plotting shear stress versus shear rate of relationships between a dependent variable and one or more variables! Really rather easy once you have a question you 'd like to ask regarding this article pascal ) in! Have converged and even crossed over description of the upper plate moving and the lower plate in.... Peak ( see fig 4. ) methods and devices available for controlling the temperature is drawn perpendicular! 11, 13 the sample should be as small as possible frequencies used. With low shear ( Brookfield ) and high shear ( Hercules ) viscosity instruments way! $ \gamma $ severe than at rest is fluid of systems cite this article in essay!

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