Showing papers on "Viscometer published in 1991"
TL;DR: A 2.0 m diameter steel 30° inverted cone-and-plate viscometer/rheometer was designed, constructed, and used to test the behaviour of coarse-grained debris flow materials as mentioned in this paper.
141 citations
TL;DR: In this article, the viscosity and density of three binary mixtures of cyclohexane with n-octane, n-dodecane, and n-hexadecane have been measured at 298, 323, and 348 K at pressures up to 150 MPa or freezing pressures.
Abstract: The viscosity and density of three binary mixtures of cyclohexane with n-octane, n-dodecane, and n-hexadecane have been measured at 298, 323, and 348 K at pressures up to 150 MPa or freezing pressures. The measurements of the viscosity were performed by a torsionally vibrating crystal viscometer on a relative basis using benzene and cyclohexane as reference materials. The density was measured using a high-pressure burette apparatus. The uncertainties of the measurements are estimated to be less than 2% for viscosity and 0.1% for density, respectively. The effects of temperature, pressure, density, and composition on the viscosity are discussed. Applicabilities of several empirical correlating equations to the viscosity data were examined.
121 citations
TL;DR: In this article, the dependence of shear viscosity on the oxidation state of six ferrosilicate melts has been measured using the concentric cylinder method and a gas mixing furnace.
Abstract: The dependence of shear viscosity on the oxidation state of six ferrosilicate melts has been measured using the concentric cylinder method and a gas mixing furnace. The measurements were performed under air, COr, and COr-CO mixtures at I atm and in a temperature range of 1345 to 1470"C. The experimental procedure involved a continuous
measurement of viscosity during stepwise reduction of the melts. Melt chemistry was controlled by dip sampling the tiquids at each oxidation state. The resulting glassesw ere
analyzed by electron microprobe, a volumetric FeO itration, and 57Fe Mdssbauer spectroscopy.
The electron microprobe data indicate Fe loss for some of the most reduced samples.T he wet chemical (+ microprobe) and spectroscopicd eterminations of theseF erich
samples yield oxidation states that are in excellent agreement. The viscosity of all melts investigated herein decreasesw ith melt reduction. The viscosity
decrease is, in general, a nonlinear function of oxidation state expressed as Fe2*/F€,o,.
89 citations
TL;DR: In this article, the viscosity of saturated liquid fluorocarbon refrigerants was measured using an improved capillary viscometer for 11 kinds of fluoroccarbon refrigerants, in the temperature range from 273 to 353 K.
Abstract: Viscosity measurements were carried out on saturated liquid fluorocarbon refrigerants using an improved capillary viscometer for 11 kinds of fluorocarbon refrigerants; CCl3F (R11), CCl2F2 (R12), CHClF2 (R22), CBrF3 (R13B1), CH3CHF2 (R152a), CCl2FCClF2 (R113), CHCl2CF3 (R123), CHClFCClF2 (R123a), CH3CF3 (R143a), CClF2CCl2F2 (R114), and CH2FCF3 (R134a), in the temperature range from 273 to 353 K. An equation is given to represent the viscosity as a function of temperature.
87 citations
TL;DR: In this article, the general rheological properties of deacetylated gellan gum (Gelrite) were examined using a purpose-built air turbine viscometer, whose independent variable was shear stress.
72 citations
TL;DR: Several non-Newtonian fluids were studied to determine how closely they simulate the flow behavior of human blood and showed large differences in velocity profiles compared to Newtonian fluids.
70 citations
TL;DR: In this paper, the surface-tension effects in kinematic capillary viscometers of the suspended-level type were investigated and it was shown that surface tension effects are sensitive to the shape of the capillary exit.
Abstract: The results of an experimental study of surface-tension effects in kinematic capillary viscometers of the suspended-level type are presented These results are deduced from a comparison with measurements obtained with a special Ostwald viscometer in which surface-tension effects are negligibly small It is shown that surface-tension effects in suspended-level viscometers are sensitive to the shape of the capillary exit Recommendations how to minimize these effects are discussed
68 citations
TL;DR: E emphasis was placed on the evaluation of viscosity at very high cell concentrations because of the lack of available data in this regime and its importance in understanding and modeling cross‐flow microfiltration of red cell suspensions, the application which motivated the current study.
Abstract: Despite the extensive previous work on the viscosity of red blood cell suspensions, experimental data at very high cell concentrations are limited and scattered, and available constitutive equations for the steady‐state viscosity are unsuitable for numerical calculations that require accurate well‐behaved analytical expressions valid over a wide range of shear rates and which include these very high cell concentrations. The steady‐state viscosity of suspensions of stored red blood cells in both saline and plasma were measured in a coaxial cylinder viscometer at shear rates ranging from below 1–300 s−1 and at cell volume fractions up to 0.98. Emphasis was placed on the evaluation of viscosity at very high cell concentrations because of the lack of available data in this regime and its importance in understanding and modeling cross‐flow microfiltration of red cell suspensions, the application which motivated the current study. This data base was supplemented by additional measurements previously reported in...
61 citations
TL;DR: In this article, a two-coil self-centering falling-body viscometer was used to measure the viscosity of three binary mixtures of toluene + n-hexane at different temperatures and pressures.
Abstract: Viscosity coefficients measured using a two-coil self-centering falling-body viscometer are reported for toluene and three binary mixtures of toluene + n-hexane at 25, 50, 75, and 100°C at pressures up to 500 MPa. The data for a given composition at different temperatures and pressures are correlated very satisfactorily by a plot of reduced viscosity η* versus log V′, where V′=V·V0(TR)/V0(T) and V0 represents a characteristic volume. The binary mixture data are well represented by the Grunberg and Nissan equation with a mixing parameter which is pressure dependent but composition and temperature independent.
50 citations
TL;DR: In this paper, the surface viscosity of beer was investigated using rotational surface viscometry to obtain information on its role as a factor in beer foam stability, and proteins were also studied in relation to the visco-temporal stability of beer foam.
Abstract: The surface viscosity of beer was investigated using rotational surface viscometry to obtain information on its role as a factor in beer foam stability. Beer proteins were also studied in relation ...
49 citations
TL;DR: In this article, a vibrating-wire viscometer for the measurement of the viscosity of liquids at pressures up to 100 MPa is described. But the design of the instrument is based on a complete theory so that it is possible to make absolute measurements with an associated error of only a few parts in one thousand.
Abstract: The design and operation of a new vibrating-wire viscometer for the measurement of the viscosity of liquids at pressures up to 100 MPa are described. The design of the instrument is based on a complete theory so that it is possible to make absolute measurements with an associated error of only a few parts in one thousand. Absolute measurements of the viscosity of n-hexane are reported at 298.15 K at pressures up to 80 MPa. The overall uncertainty in the reported viscosity data is estimated to be ±0.5%, an estimate confirmed by the comparison of values of viscosity of slightly inferior accuracy.
01 Jan 1991
TL;DR: In this paper, the surface viscosity of beer was investigated using rotational surface viscometry to obtain information on its role as a factor in beer foam stability, and proteins were also studied in relation to the visco-temporal stability of beer foam.
Abstract: The surface viscosity of beer was investigated using rotational surface viscometry to obtain information on its role as a factor in beer foam stability. Beer proteins were also studied in relation ...
TL;DR: In this paper, an in-line extrusion rheometer based on the flow of polymer through a wedge (vertically tapered slit) is presented, which is suitable for measuring changes in rheological properties on-line during reactive extrusion, because it can be used to estimate the viscosity for a range of shear rates without the need to change the polymer flow rate.
Abstract: This paper presents the development of a novel in-line extrusion rheometer based on the flow of polymer through a wedge (vertically tapered slit). This rheometer is suitable for measuring changes in rheological properties on-line during reactive extrusion, because it can be used to estimate the viscosity for a range of shear rates without the need to change the polymer flow rate (i.e., extruder throughput). Equations have been developed to estimate the parameters of the power-law equation, used to describe the viscosity-shear rate relationship, from measurements of pressure drops along the wedge. An experimental in-line wedge rheometer has been built and used to measure the viscosity for a series of polypropylenes prepared via reactive extrusion. Viscosity measurements from the experimental in-line wedge rheometer are compared with measurements from a capillary rheometer. Good agreement is found between the capillary and wedge rheometer measurements.
TL;DR: In this paper, a two-coil self-centering falling-body viscometer was used to measure viscosity coefficients for acetonitrile and three binary mixtures of toluene+ acetitrile at 25, 50, 75, and 100°C and pressures up to 500 MPa.
Abstract: A two-coil self-centering falling-body viscometer has been used to measure viscosity coefficients for acetonitrile and three binary mixtures of toluene+ acetonitrile at 25, 50, 75, and 100°C and pressures up to 500 MPa. The results for acetonitrile can be interpreted by an approach based on hard-sphere theory, with a roughness factor of 1.46. The binary-mixture data are well represented by the Grunberg and Nissan equation with a mixing parameter which is pressure and temperature dependent but composition independent.
TL;DR: In this article, the hydration process of cement pastes has been studied by means of an oscillatory rheological technique and a model has been proposed for describing the dynamic viscosity variation with time.
TL;DR: In this paper, Cogswell's method for measurement of extensional viscosity by determining the entry pressure loss in capillary viscometry is critically examined and comparisons are made between extensional values introduced in finite element calculations as input data and predictions based on calculated entry pressure losses for polymer melts.
Abstract: Cogswell's method for measurement of extensional viscosity by determining the entry pressure loss in capillary viscometry is critically examined. Comparisons are made between extensional viscosity values introduced in finite element calculations as input data and predictions based on the calculated entry pressure losses for polymer melts. The calculated pressure losses are in good agreement with experimental data by Laun and Schuch. An equation proposed by Cogswell and another by Binding are used in the extensional viscosity comparisons. The slope of the extensional viscosity versus stretch rate is predicted rather well, but the calculations can shift the results above or below the true values.
TL;DR: In this paper, the viscosities of several types of lipids saturated with supercritical carbon dioxide (SC-CO2) were measured with a high-pressure capillary viscometer.
Abstract: The viscosities of several types of lipids saturated with supercritical carbon dioxide (SC-CO2) were measured with a high-pressure capillary viscometer. Oleic acid and linoleic acid were evaluated from 85 to 350 bar at 40 and 60°C. The more SC-CO2-soluble methylated derivatives of these fatty acids were evaluated from 90 to 170 bar at 40 and 60°C. The complex mixture of anhydrous milk fat (AMF) was evaluated from 100–310 bar at 40°C. The viscosities of the methylated fatty acids saturated with SC-CO2 decreased between 5 and 10 times when the pressure increased from 1 to 80 bar, followed by a further decrease by a factor of 2 to 3 when the pressure was increased from 80 to 180 bar. The viscosities of the fatty acids and AMF saturated with SC-CO2 had viscosity reduction similar to the methylated fatty acids between 1 and 80 bar, but they decreased much less between 80 and 350 bar. At constant pressure, the viscosity of the fatty acids and AMF decreased with increasing temperature, whereas the viscosity of the methylated fatty acids increased with increasing temperature. The lipid/SC-CO2 mixtures were Newtonian, and their viscosities were best interpreted by using the mass concentration of dissolved SC-CO2 in the lipids and the pure component viscosities.
TL;DR: In this article, the apparent viscosity of a large-scale pipe is measured using a Couette and tube viscometer. But, for yet unexplained reasons, samples of cement taken from the large scale facility had much higher apparent viscoities than viscosities calculated from laminar pipe-flow data.
Abstract: The primary objective of this paper is to illustrate the inherent problems of measuring the apparent viscosity of cement slurries with laboratory viscometers and using these measurements to estimate friction factors and flow regimes in large‐scale pipes. Experimental measurements obtained with Couette and tube viscometers are shown to exhibit an apparent wall slip that reaches a limiting value of 100% at shear stresses near the yield value. Nevertheless, comparable apparent viscosities are obtained after these data are corrected for slip. Experimental results for the laminar, transitional, and turbulent flows of clay and cement slurries in a large‐diameter pipe are also presented. It is shown that the onset of turbulence occurs at a critical Reynolds number that is in good agreement with the predicted value, provided that rheological properties are based on large‐scale pipe‐flow data. However, for yet unexplained reasons, samples of cement taken from the large‐scale facility had much higher apparent viscosities (as determined from a Couette viscometer) than viscosities calculated from laminar pipe‐flow data.
TL;DR: Increased plasma fibrinogen was measured in six of six resting subjects taken from 1600 m to 3300 m and is speculated to be the mechanism of enhanced aggregation and deformability in the runners.
Abstract: The effect of endurance training on blood viscosity was studied by comparing blood rheological properties in control subjects (untrained) and endurance trained subjects. The effect of running on blood viscosity was studied in the 33 endurance trained subjects before and after a 48-km mountain race (Sandia Wilderness Crossing Research Run). Runners started at an altitude of 1700 m, ran 26 km to 3300 m, then descended 22 km to finish at 1900 m. Venous blood viscosity (eta b) and plasma viscosity (eta p) were measured at 37 degrees C at shear rates of 11.25, 22.5, 45, 90, and 225.s-1, using a cone-plate viscometer. Endurance trained subjects had significantly higher pre-race blood viscosity at 11.25 and 22.5.s-1 than control subjects but similar plasma viscosity and hematocrits. Following the race, there was no significant change in mean hematocrit, but eta b increased significantly at all shear rates except 225.s-1. Plasma viscosity at 225.s-1 increased significantly from 1.44 to 1.53 cP following the run. Since eta b did not increase, an increase in red cell deformability is inferred. The mechanism of the increase in eta b at lower shear rates in runners is due in part to the higher plasma viscosity. An additional mechanism at lower shear rates is in an increase in red cell aggregation. Increased plasma fibrinogen was measured in six of six resting subjects taken from 1600 m to 3300 m and is speculated to be the mechanism of enhanced aggregation and deformability in the runners.
TL;DR: It was observed that the viscosity of the mineral oil phase prior to mixing had little effect on the average diameter of the microspheres, until a high concentration of light mineral oil was used.
Abstract: The influence of the viscosity of the internal and external phases and the interfacial tension between the two phases, in the emulsion type of microencapsulation system was investigated. The viscosity of mineral oil (external phase) was measured by a capillary viscometer and the viscosity of cellulose acetate trimellitate solution (internal phase) was measured by a Brookfield viscometer. The viscosity of the two phases were measured prior to mixing and at 5 and 60 min after mixing the phases. It was observed that the viscosity of the mineral oil phase prior to mixing had little effect on the average diameter of the microspheres, until a high concentration of light mineral oil was used. A graph of viscosity ratio of the internal phase to the external phase shows that a minimum viscosity ratio may be required before particle size increases. Results are discussed with respect to viscosity effects of mineral oil and polymer solution, as influenced by the solvent uptake by the mineral oil. The interfac...
TL;DR: In this paper, the free volume theory of Prigogine-Flory-Patterson (PFP) and the experimental excess enthalpy have been used to estimate excess viscosity Δ ln η = (ln η/η10 − x2 ln σ ln ǫ 20/ǫ 10) for six binary mixtures of n-butylamine: triethyl, tripropyl, tributyl, trihexyl and trioctylamine with cyclohexane.
Abstract: Viscosities for six binary mixtures of n-butylamine, di-n-butylamine, tri-n-butylamine, n-octylamine, di-n-octylamine, and tri-n-octylamine with cyclohexane have been measured at 303.15 K with an Ubbelohde suspendedlevel viscometer. Deviations of viscosities from a rectilinear dependence on mole fraction are attributed to H-bonding and to the size of alkylamine compounds. The application of the Eyring's theory of activation energy is examined. The free volume theory of Prigogine-Flory-Patterson (PFP) and the experimental excess enthalpy have been used to estimate excess viscosity Δ ln η = (ln η/η10 − x2 ln η20/η10) and corresponding free volume, enthalpy, and entropy contributions for five binary mixtures of tri-n-alkylamine: triethyl, tripropyl, tributyl, trihexyl, and trioctylamine with cyclohexane. A comparison of experimental and theoretical excess viscosities indicates a failure of the PFP theory when two components of the mixture differ considerably in size. The size difference contribution to excess viscosity is related to (V2*1/2 − V1*1/2), where V1*and V2*are hard-core volumes of two components of the mixture.
TL;DR: In this paper, the Brabender plastometer and rotating viscometer are used as dynamic methods and the differential scanning calorimeter is used as a static method to test gelling.
TL;DR: In this paper, phase equilibria, density, and rheological behavior of the coexisting phases are measured as a function of pressure, temperature, and composition, and an experimental system consisting of an autoclave, a capillary viscometer, and a density measuring device was constructed.
Abstract: An experimental system consisting of an autoclave, a capillary viscometer, and a density measuring device was constructed. Phase equilibria, density, and rheological behavior of the coexisting phases are measured as a function of pressure, temperature, and composition. The following systems are investigated: pelargonic acid/CO2; pelargonic acid/C2H6; oleic acid/CO2; oleic acid/C2H6; linoleic acid/CO2; linoleic acid/C2H6; valeric acid/C2H6. At flow rates up to 1000 sec−1, the coexisting liquid phases of the systems pelargonic acid/CO2 and pelargonic acid/C2H6 show dilatant flow behavior. The others show Newtonian flow behavior. The viscosity of the coexisting gas phase increases with increasing pressure whereas the viscosity of the liquid phase decreases. The density of the liquid phase of systems containing ethane decreases with increasing pressure (i.e., increasing gas content) whereas that of systems containing CO2 increases.
TL;DR: In this paper, relative measurements of the viscosity of liquid toluene are reported for the temperature range 218 to 378 K. The experimental data have been correlated well within these estimates by an empirical temperature function.
Abstract: New relative measurements of the viscosity of liquid toluene are reported for the temperature range 218 to 378 K. They supplement the existing data, which have been obtained mostly above 273.15 K. The relative accuracy of the results is estimated between −1 and 1.38% at 218 K, narrowing to one of −0.74 and 1.12% at 378 K. The experimental data have been correlated well within these estimates by an empirical temperature function. A comparison with previous experimental and compiled or evaluated data includes references since 1894 and is the most comprehensive survey so far. The agreement with the present data is generally very good. There is a need for further measurements with instruments other than capillary viscometers and in the low-temperature range from the triple point (178.15 K) to 273.15 K.
TL;DR: In this paper, an acoustic wave viscometer using shear bulk waves excited by interdigital transducers on quartz is presented, which can be used for viscosity measurements up to 600 cP.
Abstract: This article presents an acoustic wave viscometer using shear bulk waves excited by interdigital transducers on quartz. The attenuation of acoustic waves at the quartz‐liquid interface is associated with liquid viscosity. Good agreement is found between theoretical results and experiments. The device can be used for viscosity measurements up to 600 cP. For higher viscosity the high‐frequency rigidity modulus must be taken into account.
TL;DR: In this article, the authors investigated the stress deformation behavior of a non-Newtonian surface subject to an oscillatory shearing flow and interpreted the rheological properties of such an interface using the complex viscosity surface fluid model.
TL;DR: In this paper, the phase-inversion of a w/o/w emulsion was examined by a cone-and-plate viscometer and the impulse applied by the rotating cone was the parameter determining the phase inversion.
TL;DR: In this article, the authors studied the effect of temperature dependence of the viscosity on the stability of Couette flow between two parallel plates and found that the flow becomes unstable with increasing viscosities.
Abstract: This paper studies the effect of temperature dependence of the viscosity on the stability of classical Couette flow between two parallel plates. When the viscosity increases with temperature, it is well known that the flow becomes increasingly stable. With decreasing viscosity, however, if the dependence is sufficiently strong, the flow is found to become unstable.
TL;DR: In this article, a concentric cylinder viscometer in the temperature range from 30°C to 80°C was used to investigate the viscoelastic properties of ketchups.
Abstract: Ketchup flow properties were investigated with a concentric cylinder viscometer in the temperature range from 30°C to 80°C. A partial characterization of the product viscoelastic behavior at 30°C was also made by “Strain test” and “Frequency test.” The Harper and El Sahrigi equation (ηa= acβ eEa/RT), as well as the equation that links the apparent viscosity of ketchups to the serum viscosity and to the pulp content (ηa=ηserum+A(%P)B), do not describe adequately the ketchup flow behavior that we found to be highly affected by the production technology and by the raw materials used.
TL;DR: In this paper, the shear viscosity of saturated 3He-4He mixture has been measured at temperatures between 7 mK and 200 mK using a vibrating-wire viscometer and a calibrated pressure cell.
Abstract: The shear viscosity of saturated3He-4He mixture has been measured at temperatures between 7 mK and 200 mK using a vibrating-wire viscometer and a calibrated pressure cell. The reliability of the vibrating-wire technique was tested by measuring the viscosity of pure4He. The results are internally consistent. A phenomenological expression is given for the viscosity of saturated3He-4He mixture between 7 mK and 80 mK.