High shear viscosity measurement pdf

Standard test method for measuring viscosity at high shear. Stress and straincontrolled measurements of interfacial. Viscosities of turbulent systems can be as high as 10 6 times greater than viscosities of laminar systems, depending on the reynolds number. Thiscorrespondstoaslopeof 1 onaloglog plot of viscosity versus shear rate. Standard test method for highshear viscosity using the. Measurement techniques for the shear dependence of viscosity at. The apparent shear rate at the wall for this test method is increased to compensate for the variable shear rate. The shear rate in capillary viscometers varies across the radius of the capillary. In the science of rheology, a fluids changes are measured when there are actual forces mechanical shear or pump pressure induced. For more than a quarter century we have served the oil and gas. However, the weight is replaced by a driving motor, which realizes high shear stress values up to 900 kpa and medium to high shear rates around 1,500 s1. This greatly affects the measurement accuracy and reproducibility figure 7, and is difficult to eliminate even if serrated or crosshatched test fixtures are used. Viscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or tensile stress.

More olutions to ticky problemss making rheological measurements equipment for speci. Measurement and prediction of fluid viscosities at high shear rates. Clearly single point viscosity measurements could not provide the information required to describe the complex rheological behavior of such nonnewtonian paints. For most liquids, including hydrogen bonded, weakly associated or unassociated, and polymeric liquids as well as liquid metals. At the end of one single point measurement, an apparent viscosity a is reported by the software. Whitepaper applications optimizing rheology for paint and coating. Shear thinning liquids are very commonly, but misleadingly, described as thixotropic. Shear thickening fluids are sometimes called dilatant fluids, because many are high concentration slurries that must expand dilate at the particle level in order to flow. This, in itself, restricts the engineering and measurement. The leader in viscosity measurement technology cambridge viscosity is the global leader in small sample fluid viscosity measurement. Standard test method for measuring apparent viscosity at.

Extensional viscosity, a linear combination of shear and bulk viscosity, describes the reaction to elongation, widely used for characterizing polymers. Mar 10, 2016 normally id just expect that to be referred to as zero viscosity. The duration for which the shear rate is applied was 30 s. For example, highviscosity felsic magma will create a tall, steep stratovolcano, because it cannot flow far before it cools, while lowviscosity mafic lava will create a wide, shallowsloped shield volcano. Melt viscosity is a constant at low shear rates or frequencies. The latter term describes the degree to which a material is shear thinning n shear thickening n 1.

The viscosity of nonnewtonian fluids depends on the magnitude of the flow and the length of time the fluid has been flowing. High shear mixers hsms, characterized by their highly localized energy dissipation, are widely used in process industries for dispersed phase size reduction and reactive mixing. This is not simply resistance to flow, as in viscosity measurement. At high temperatures, low shear conditions are seen in leak paths oil seals, behind piston rings and having too low a viscosity. D 4683 04 an american national standard standard test method for measuring viscosity at high shear rate and high temperature by tapered bearing simulator1 this standard is issued. Our sensors and viscometer systems conform to astm, din. Stress and straincontrolled measurements of interfacial shear viscosity and viscoelasticity at liquidliquid and gasliquid interfaces philipp erni, peter fischer, and erich j. Measurement and prediction of fluid viscosities at high shear rates jeshwanth k. In everyday terms and for fluids only, viscosity is thickness.

The shear rate and shear stress are directly related to the geometry of the rectangular slit and the flow rate which allow for viscosity measurements. Viscosity is the measure of a substances resistance to motion under an applied force. If you are on this site, you probably have a general idea about what is viscosity and how important it is in the development of any application that involves fluid flow. For low molecular weight polymers in which chain entanglement is not a factor, the zero shear viscosity. For example, at room temperature, water has a dynamic shear viscosity of about 1. Viscosity the resistance of a fluid to shear or tensile stress is an indispensable measurement in fluid analysis. The trouton ratio or troutons ratio is the ratio of extensional viscosity to shear viscosity. Thus, water is thin, having a lower viscosity, while honey is thick, having a higher viscosity.

Pce instruments offers a variety of handheld, portable, benchtop and inprocess, realtime viscometer products that measure the absolute dynamic shear and kinematic viscosity of fluids. Flow curves generated with a highpressure couette viscometer. A common example of shear thickening fluids is a mixture of cornstarch and water. Rotating concentric cylinders couette good for low viscosity, high shear. For most liquids, the viscosity decreases with temperature. Shear viscosity is a measure of resistance to isochoric flow in a shear field, whereas. In addition to reporting viscosity, this instrument produces a rheogram whose shape has been used to predict flow performance of a material as it reacts to changes in shear. Handheld or portable viscosity meter devices allow users to take simple, singlepoint measurements. The major limitation of the jet viscometer is an inability to distinguish quantitatively between energy losses in laminar flow and those due to capillary geometry and experimental conditions. Shear viscosity is a measure of resistance to isochoric flow in a shear. Characterization of pressure sensitive adhesives by rheology.

The precision has not been studied for any temperature or viscosity. Ultra high shear mixing strategies page 3 of 9 premax batch ultra high shear mixer the ross premax is a topentering batch ultra high shear mixer equipped with the patented delta rotorstator assembly. Circular couette viscometer for very high pressure for very low viscosity base oils, in a measurement of shear dependent viscosity, the pressure must be very high to avoid thermal softening. The measurements are restricted mainly by the torque resolution at low shear rates and by inertia at high shear rates. Shear thinning is the result of microstructural rearrangements occurring in the plane of applied shear and is commonly. Evaluation of high shear viscosity data from jet and. The obvious recourse is to actually measure viscosity at these very high shear rate conditions above 51 06seci and this was the focus of the present work. Thus, to measure or consider the viscosity or rheology at only one shear rate is fairly meaningless on its own.

In addition, while testing high viscosity semisolid materials, such as grease or paste, wall slippage might occur between the geometry and the sample. Because a diverse range of shear rates prevails in. Viscosity defined as a materials resistance to deformation and is a function of shear rate or stress, with time and temperature dependence viscoelasticity is a property of a material that exhibits both viscous and elastic character. Chiu describes how the modulus values at high frequency are related to peel or quick stick tests, and at low frequencies, to shear resistance of adhesives 2. High temperature viscosity high shear viscometer small. Viscosity measurements in food products and manufacturing. Shear viscosity measurement of highly filled polycarbonate. Good for highviscosity fluids, small sample volume, gives shear and. If a test with any geometries runs through a table of several shear rates or stresses, the data can be used to plot a flow curve, that is a graph of viscosity vs shear rate. Further information can be obtained by using the coxmerz rule 3 to predict shear viscosity. More olutions to ticky problems s university of utah.

High pressure viscosity measurement with falling body type. Standard test method for measuring apparent viscosity at high. Tts is applied to obtain the extended frequency range the high. Measurements using narrow gap couette flows between concentric cylinders and between parallel plate fixtures have been used to measure the viscosity of. In this study, a slitdie rheometer mounted on an injection molding machine is employed to measure the shear dependent viscosity of. Shear viscosity is a measure of resistance to isochoric. High pressure capillary viscometers with electric drive. A new method to measure the viscosity of nonnewtonian fluids over a wide range of. A method to evaluate the flow properties of paints and specifically leveling based on the rheology of sheared paint samples, as a function of time and at variable low, and ultralow shear rates. Measurement and prediction of fluid viscosities at high.

This work compares and evaluates viscosity data obtained on similar fluids by two widely accepted high shear techniques. Density, viscosity, extrusion, polymer melt, shear waves, longitudinal waves, ultrasonic measurements. Rheometer an instrument that measures both viscosity and viscoelasticity of fluids, semisolids and solids it can provide information about the materials. Troutons ratio is the ratio of extensional viscosity to shear viscosity. Turning at 5,000 ftmin, the rotor is specially contoured for high pumping capacity and shear intensity. However, there is a bulk viscosity, or volume viscosity, which characterizes dissipation due to rapid changes in volume.

The pressure drop is correlated with the shear stress at the boundary wall. The zero shear viscosity is a sensitive measure of polymer molecular weight. As concentration increases, one may expect higher viscosities. The zero shear viscosity increases with increasing molecular weight. For this reason airbearing rheometer such as our ar2000 is a necessity for measurement of zero shear viscosity. Shear viscosity measurement of highly filled polycarbonate melts. Timedependent nonnewtonian fluids change apparent viscosity not only with shear rate, but also during and following the applied shear.

Standard test method for measuring viscosity at high. The measurement of viscosity at elevated pressures, however, is not quite so straightforward. On the other hand, polymer solutions, slurries, pastes, and paints are frequently nonnewtonian. Turning at 5,000 ftmin, the rotor is specially contoured for high pumping capacity and shear.

Viscositydefined as a materials resistance to deformation and is a function of shear rate or stress, with time and temperature dependence. Molecular viscosity is separated into shear viscosity and bulk or volume viscosity. The precision has not been studied for any temperature or viscosity range not noted in the precision section. This is achieved by the use of a different range of newtonian calibration fluids. Measuring low viscosities and high shear rates with a.

Ultrahigh shear mixing strategies page 3 of 9 premax batch ultrahigh shear mixer the ross premax is a topentering batch ultrahigh shear mixer equipped with the patented delta rotorstator assembly. Measurement for most coatings a fixed low shear rate ca 200 s1 is used to measure the viscosity either in the development or. Viscosity measurement series constanttemperature baths for viscometers glass viscometers. Viscosity can be thought of as a resistance to flow, with highly viscous fluids being more resistant to flow.

Cambridge viscosity has set the standard for extraordinarily precise, reliable, and virtually maintenancefree viscosity measurement systems. Steadystate viscosity measurement for mozzarella cheeses therefore changes the structure of the cheese thus changing the viscosity that we are trying to measure. For water based decorative we tend to look at low, medium, and high shear viscosity as defined above, with an emphasis on low and medium shear. The result is typically expressed in centipoise cp, which is the equivalent of 1 mpa s millipascal second. Hence a single viscosity measurement is not sufficient to describe the viscosity of such materials and the viscosity should be measured over a range of shear rates or stresses, or at least at a shear rate relevant for the process or application of interest. Viscosity and density measurement methods for polymer melts. For example, highviscosity felsic magma will create a tall, steep stratovolcano, because it cannot flow far before it cools, while lowviscosity mafic lava. Such a viscometer works in the same way as a weightdriven instrument see the above section. Because the ht75 standard has a nominal viscosity of 2. The measurement of chocolate viscosity is highly specialised and requires a specific type of viscometer for the measurement to be performed accurately. Ten steps to a better rheological measurement 2005 rheology training seminar. Even for a newtonian fluid, the viscosity usually depends on its composition and temperature.

Polymeric materials in general are viscoelastic in nature because they exhibit strong depend. Knowledge of viscous behavior over a wide range of shear. Standard test method for highshear viscosity using the ici a. This is due to the need for high pressure containment.

The ici coneplate viscometer gives this shear rate with must provide a viscosity measurement rage of either 0 to 10p 0 to 1 pas and 10 p or 0 to 5 p c at the above mentioned shear. High temperatures measured in terms of kinematic viscosity at 100c kv 100. The viscosity can easily be calculated from shear stress from the torque and shear rate from the angular velocity. Measurement techniques for steady shear viscosity of.

The flow properties are usually described by the casson flow curve and for this it is necessary to make measurements at different rotational speeds so that shear stresses at different shear. Bingham plastics that behave as a solid at low stresses but flow as a viscous fluid at high stresses. Whitepaper applications optimizing rheology for paint and. A fluid is shear thickening if the viscosity of the fluid increases as the shear rate increases see figure 2. Both the jet and concentric cylinder viscometers are useful high shear methods. The ici coneplate viscometer gives this shear rate with must provide a viscosity measurement rage of either 0 to 10p 0 to 1 pas and 10 p or 0 to 5 p c at the above mentioned shear rate. Zero shear viscosity measurement necessitates the use of a highly sensitive instrument that can impart very small stresses and measure incredibly low shear rates. The formula for measuring viscosity is fairly simple. It makes provision for limiting low and high shear newtonian viscosity behavior eq. The viscosity of the liquid is calculated from the torque measurement at the maximum shear rate. What rotational speeds or shear rates are important.

Therefore, viscosity measurements at a constant shear rate or singlepoint measurements are inadequate to describe the flow behavior of nonnewtonian fluids. Understanding the role of viscosity, and measuring it, is key to correctly analyzing many engineering situations. Note the cannon high temperature high shear series ii viscometer meets the high shear testing requirements of astm d 5481. At high temperatures, low shear conditions are seen in leak paths oil seals, behind piston rings and having too low a viscosity can affect oil consumption. What is viscosity, and why is measuring viscosity important. For newtonian materials where viscosity is independent of applied shear stress then temperature is the main variable, however, to provide the requisite functionality most paints and coatings tend to be nonnewtonian, where viscosity is a function of the applied shear stress or shear rate. The generalized newtonian model is extremely useful in engineering calculations of flow but it has some interesting limitations to be seen in the next sections. This, in itself, restricts the engineering and measurement options available. Commercial cap illary rheometers allow the measurement of shear vis cosity of unreinforced polymer melts at high shear rate regions, but the process is time. Typical applications and studies on power draw, flow pattern, energy dissipation and transfer properties. Always watch the normal stress during a shear viscosity measurement. A basic introduction to rheology technology networks. This defines the oils sae high temperature grade example, the 30 in 10w30.

Measurement of viscosity at high temperature can be. You have probably seen examples of this on tv or the internet, where people can run over this kind of solutions and yet. Pdf highshearrate capillary viscometer for inkjet inks. Viscosity measurement ranges depend upon the cone spindle and the rotational speed shear. The viscosity in this region is known as the zero shear, or newtonian, viscosity ho. For industrial, oem, refinish, hdc, coil, and aerospace coatings low and ultra high shear sometimes medium and high shear as well are important. Viscosity describes a fluids internal resistance to flow and may be thought of as a measure of fluid friction. Although viscosity measurements can be used as probing tools for changes in structure we wish to measure steady shear viscosity before any significant structural change has occurred. Due to the physical complexity of inks, viscosity measurement over a wide range of shear rates low and high shear regimes must to be performed for better understanding, which leads to better control.