Showing papers on "Viscometer published in 1988"
TL;DR: In this article, the authors present a new analysis of the Couette geometry that requires only two measurements rather than the three used by Mooney, and demonstrate the experimental data on a clay suspension and oil-in-water emulsion.
Abstract: Often for slurries, gels, emulsions, and foams inhomogeneous fluid properties at solid boundaries create “apparent wall slip.” The reduced fluid viscosity at the boundary creates a thin layer of fluid having a large velocity gradient that can be treated as a “slipping layer”. In measurements of fluid viscosity it is necessary to correct for wall slip to determine the true deformation experienced by the bulk of the sample and the true viscosity. The classic earlier techniques for capillaries and Couette geometries were first presented by Mooney. We present a new analysis of the Couette geometry that requires only two measurements rather than the three used by Mooney. We also present a new analysis for flow between rotating parallel disks. The parallel disk geometry has several experimental advantages for measuring fluid viscosities in the presence of wall slip. The analysis of experimental data on a clay suspension and oil‐in‐water emulsion are presented to demonstrate these new techniques.
494 citations
TL;DR: In this paper, the authors measured the shear viscosity of commercial maize grits, potato powder and a low density polyethylene using an extruder-fed slit die viscometer and a capillary rheometer.
Abstract: The shear viscosity of commercial maize grits, potato powder and a low density polyethylene has been measured under a range of extrusion processing conditions using an extruder-fed slit die viscometer and a capillary rheometer. The results show the strong dependence of the viscosity of food melts on the processing history undergone during extrusion. To this end, the shear viscosity data for the food materials have been fitted to relationships including the effects of temperature, shear rate and moisture. The effect of the shear processing history on the viscosity has been represented by a power-law relationship with extruder screw speed.
84 citations
TL;DR: The complex viscosity (eta = eta' - i eta") of the bulk liquid of human submandibular saliva below the absorbed layer was measured in the frequency range 70 Hz-200 kHz with 3 torsional resonators, each for a different frequency, and a Ni-tube resonator and the value of eta" was too small to be detected.
82 citations
TL;DR: In this paper, the authors used a concentric cylinder viscometer to measure the shear stress-shear rate of five commercial salad dressings at 2.0, 10.0 and 10.3°C.
Abstract: Shear stress-shear rate data of five commercial salad dressings at 2.0, 10.0, 18.3, 26.7, 32.2 and 43.3°C were obtained using a concentric cylinder viscometer. The power law and Casson equations were applicable for all products (r ≫ 0.98). The Arrhenius equation was applicable for the effect of temperature on the apparent viscosity at 100 s−l (r ≫ 0.97). Rheological data were obtained at a constant shear rate of 275s−l at 2.0 and 10.0° C. The results show that the Weltman equation was better than the Hahn equation in describing the thixotropic behavior of the five salad dressings.
59 citations
TL;DR: In this paper, the viscosity coefficient of methane at 25°C has been measured at pressures from 1 to 10 000 bar by means of the vibrating wire viscometer.
Abstract: The viscosity coefficient of methane at 25°C has been measured at pressures from 1 to 10 000 bar by means of the vibrating wire viscometer. The same behaviour has been found for methane as for argon with earlier measurements, except at the very highest pressures from 8 to 10 kbar. In this range the viscosity coefficient η of methane deviates from the expected behaviour, presumably due to hindered rotation of the molecules. This appears in the Batschinski-Hildebrand representation as a third linear relation between the fluidity and the molar volume in the high density range. The comparison of the results with molecular dynamic computations for hard spheres shows a similar deviation from the expected behaviour.
56 citations
TL;DR: A new capillary viscometer (Coulter Viscometer II), which gives an automated measurement of plasma viscosity, was compared with the selected manual method of the International Committee for Standardization in Haematology.
Abstract: Plasma viscosity has several advantages over the erythrocyte sedimentation rate as a measurement of an acute phase response of more than 24 hours9 duration. A new capillary viscometer (Coulter Viscometer II), which gives an automated measurement of plasma viscosity, was compared with the selected manual method (Harkness viscometer) of the International Committee for Standardization in Haematology. Automated measurement of plasma viscosity at 25 degrees C showed close correlation (r = 0.979, p less than 0.002) with the selected method for 160 specimens of plasma. Satisfactory precision both within batch and between batch (coefficients of variation of 1.7% or less) was obtained at viscosity values up to 5.7 mPa.s. There was no detectable carry over between samples and viscosity values were corrected adequately for ambient temperature for the range 15-32 degrees C. Careful daily cleaning was required to prevent accumulation of protein within the automatic sampling valve of the instrument. Automated measurement of plasma viscosity is an attractive alternative to measurement of the erythrocyte sedimentation rate.
50 citations
TL;DR: The viscometer was used to carry out a series of preliminary studies in which platelet-rich plasma was subjected to continuous and pulsatile shear stress at 37 degrees C and shear-induced platelet aggregation was significantly greater in response to pulsatile versus continuous shearing except at the lowest applied stress.
43 citations
TL;DR: In this article, the use of data from the falling needle viscometer to determine the rheological properties of purely viscous non-Newtonian fluids is described and a technique for measuring fluid densities using this instrument is presented that is applicable to both Newtonian and power law fluids.
Abstract: The use of data from the falling needle viscometer to determine the rheological properties of purely viscous non‐Newtonian fluids is described. From the solution of the basic flow equation, which is given in tabular and graphical form, a method is presented to determine rheological flow curves for both power law and more generalized rheological fluids. The use of the instrument to determine the zero shear rate viscosity is also described and a method of fitting appropriate constitutive equations to the data is discussed and illustrated by examples. Finally, a technique for measuring fluid densities using the falling needle viscometer is presented that is applicable to both Newtonian and power law fluids.
41 citations
TL;DR: In this paper, the synthesis and semiconcentrated and dilute solution properties of two series of ampholytic acrylamide ionomers are reported as a function of the ionic content and added salt concentration.
Abstract: The synthesis and semiconcentrated and dilute solution properties of two series of ampholytic acrylamide ionomers, poly(acrylamide MPTMA/AMPS) and poly(acrylamide METMA/MES), are reported as a function of the ionic content and added salt concentration. The viscosity dependence on shear rate was measured with a cone/plate Brookfield viscometer for sermiconcentrated solution and with a Cannon-Ubbelohde four-bulb shear dilution capillary viscometer for dilute solution at 25 ± 0.1°C. The two series of ampholytic acrylamide ionomers showed a characteristic pseudoplastic shear-thinning behavior under both conditions. The semiconcentrated solution viscosity parameters m and n in the power-law model, η = mγn-1, were determined and found to be functions of the ionic content. The viscosity at selected shear rates was found to be a complex function of the salt concentration. The intrinsic viscosity [η] was determined and compared with molecular parameters determined by light scattering under identical condi...
37 citations
LGC1
TL;DR: In this paper, the effects of various additives on the setting of the glass-ionomer cement system were studied by means of cone and plate viscometry, and it was found that (+)-tartaric acid had a dual effect on setting, first inhibiting gelation and then accelerating it.
Abstract: The effects of various additives on the setting of the glass-ionomer cement system was studied by means of cone and plate viscometry. The action of (+)-tartaric acid, the most important additive, on the setting reaction depended on its concentration. Low concentrations accelerated the development of viscosity of the cement paste, while high concentrations retarded it. At intermediate concentrations, (+)-tartaric acid had an interesting, uniquely favorable effect on setting characteristics. First, it induced a lag period in the setting process during which the viscosity of the cement paste remained constant. This lag period was followed by a sharp, almost exponential, increase in viscosity. Thus, (+)-tartaric acid was found to have a dual effect on setting, first inhibiting gelation and then accelerating it. The practical effect is to prolong working time and sharpen setting. No other hydroxyacid, not even meso-tartaric acid, combined these advantageous effects. Meso-tartaric acid, for example, repressed the development of viscosity at all stages of the reaction. Other hydroxyacids either accelerated or retarded the development of viscosity throughout the course of the reaction.
37 citations
TL;DR: In an attempt to resolve the difficult problem of on‐line determination of the viscosity of non‐Newtonian fermentation media, the authors have used a vibrating rod sensor mounted on a bioreactor.
Abstract: In an attempt to resolve the difficult problem of on-line determination of the viscosity of non-Newtonian fermentation media, the authors have used a vibrating rod sensor mounted on a bioreactor. The sensor signal decreases nonlinearly with increased apparent viscosity. Electronic filtering of the signal damps the interfering effect of aeration and mechanical agitation. Sensor drift is very low (0.03% of measured value per hour). On the rheological level the sensor is primarily an empirical tool that must be specifically calibrated for each fermentation process. Once this is accomplished, it becomes possible to establish linear or second-degree correlations between the electrical signal from the sensor and the essential parameters of the fermentation process in question (pH of a fermented milk during acidification, concentration of extra cellular polysaccharide). In addition, by applying the power law to describe the rheological behavior of fermentation media, we observe a second-order polynomial correlation between the sensor signal and the behavior index (n).
TL;DR: In this article, the authors measured the viscosity of polysaccharides at high temperatures using a slit viscometer and found that alginate is much less stable than carboxymethyl cellulose and carrageenan.
TL;DR: In this article, the rheological properties of concentrated coal and quartz were determined in a cup-and-bob viscometer in the laminar flow region, using a ridged bob and cup.
TL;DR: In this paper, the extrudate swell measurements were carried out for slit and capillary dies for several elastomers and their compounds, including natural rubber (NR), styrene-butadiene rubber (SBR), ethylene-propylene terpolymer (EPDM), and polychloroprene (CR) compounds.
Abstract: Rheological characterization, extrudate swell measurements, and a flow marker extrusion study for several elastomers and their compounds is reported. The materials included natural rubber (NR), styrene–butadiene rubber (SBR), ethylene–propylene terpolymer (EPDM), and polychloroprene (CR) and their carbon black compounds. The shear viscosity was measured with a sandwich rheometer, a shearing disk viscometer, and a capillary rheometer over a wide range of shear rates. Evidence for yield values is found in compounds with 0.20 and 0.30 levels of carbon black. Empirical equations were fit to the data. Extrudate swell measurements were carried out for slit and capillary dies. Increasing the level of carbon black reduces the level of swell. Flow marker experiments were carried out in the barrel of a capillary rheometer using a wide range of die designs. These indicated roughly radial streamline flows into the capillary or slit land. Recessed parts of a die could accumulate stagnant material. Evidence for wall slippage in the rheometer barrel for compounds with 0.20 and 0.30 volume fractions of carbon black is discussed.
TL;DR: In this paper, the authors measured the viscosity of aqueous solutions of 1,2-ethanediol (ethylene glycol) and 1, 2-propanediol (propylene glycol), at 298 and 323 K under pressures up to 120 MPa.
Abstract: New experimental data on the viscosity of aqueous solutions of 1,2-ethanediol (ethylene glycol) and 1,2-propanediol (propylene glycol) are presented at 298 and 323 K under pressures up to 120 MPa. The measurements were performed by a falling-cylinder viscometer on a relative basis with an uncertainty of less than ±2%. The viscosity of these aqueous solutions at a constant temperature and pressure increases monotonously with increasing concentrations of diols (glycols) and is slightly lower than the mole fraction average value at each composition. The viscosity also increases almost linearly with pressure at a constant temperature and composition. The pressure coefficient of the viscosity, (∂η/∂P)T,x, increases with decreasing temperature and increasing concentrations of diols. The experimental results are correlated with pressure, density, and composition by several empirical equations.
TL;DR: In this article, the viscosity of water at 20°C and atmospheric pressure is 1.0006 mPa s ± 0.05% at the 68% confidence level.
Abstract: The viscosity of water has been measured with high accuracy in the temperature range 19.5–25.5°C, using an absolute oscillation viscometer. The resulting data are represented by the modified Arrhenius expression In (η/mPa s) = 1.85191 - 3201.27 K/ T + 779359 K 2 / T 2 . The viscosity of water at 20°C and atmospheric pressure is 1.0006 mPa s ± 0.05% at the 68% confidence level. This value is 0.13% lower than the currently recommended value at 20°C: 1.002 ± 0.001 mPa s.
TL;DR: In this paper, a rotational rheometer with helical screw impeller is proposed to determine the flow curve of the investigated fluid, and a procedure for flow curve determination is proposed.
Abstract: The paper is concerned with the development of an on-line rheometer for suspensions with settling particles. A new concept of a rotational rheometer with helical screw impeller is discussed. On the basis of model considerations a procedure for the flow curve determination of the investigated fluid has been proposed. Contrary to previous attempts, in the developed procedure no calibration of the instrument is necessary. The preliminary experimental verification of the developed approach proved its applicability.
TL;DR: In this paper, the final in a series of three viscosity and density studies of pure n-alkanes and selected binary and quaternary mixtures was performed using a standard U-tube viscometer and a Pyrex flask-type pycnometer was used for density determinations.
Abstract: This paper is the final in a series of three viscosity and density studies of pure n-alkanes and selected binary and quaternary mixtures. A standard U-tube viscometer was used for viscosity measurements, and a Pyrex flask-type pycnometer was used for density determinations. Results are given here for pure alkane and selected binary mixtures of n-tetradecane + n-octane, for selected quaternary mixtures of n-hexadecane + n-dodecane + n-decane + n-hexane, and for pure and selected quaternary mixtures of n-hexadecane + n-dodecane + n-nonane + n-heptane at 303.16 and 308.16 K. The principle of congruence was tested, as was the Grunberg and Nissan equation, as they have been shown to be useful as prediction techniques for other n-alkane binary mixtures. Comparisons were made between the two groups of quaternary alkane mixtures and the binary n-tetradecane + n-octane mixtures of the same “pseudo” composition to understand better the dependence of mixture viscosities on the composition parameter.
TL;DR: In this article, the shear viscosity coefficients of three compressed gaseous and liquid carbon dioxide + ethane mixtures have been measured with a torsional piezoelectric crystal viscometer at temperatures between 210 and 320 K and at pressures to about 30 MPa (4350 psi).
Abstract: The shear viscosity coefficients of three compressed gaseous and liquid carbon dioxide + ethane mixtures have been measured with a torsional piezoelectric crystal viscometer at temperatures between 210 and 320 K and at pressures to about 30 MPa (4350 psi). The experimental error is estimated to be smaller than 3 percent in most cases. The measurements have been compared with an extended corresponding states model, and used to examine the dependences of the fluidity (reciprocal viscosity) on specific volume, composition and temperature.
TL;DR: In this paper, the authors used a pseudoplastic frankfurter batter with a flow behavior index of 0.2-0.4 and a yield stress of approximately 840 Pa at 10°C.
Abstract: Good agreement was observed between the shear stress-shear rate results obtained with a capillary extrusion viscometer and the yield stress as determined with a rotational viscometer. The frankfurter batter used in this study was pseudoplastic with a flow behavior index of 0.2–0.4, and a yield stress of approximately 840 Pa at 10°C. To compare the effects of batter composition, an apparent viscosity term was defined. Dilution of the batter resulted in reduced apparent viscosities, while increased fat led to increased apparent viscosities. Although chopping time significantly altered the stability of the batter and the visco-elastic properties of the cooked product, no significant difference in the apparent viscosity was detected. This observation was discussed in light of the apparent insensitivity of viscosity measurements to the degree of fat comminution.
TL;DR: In this article, the authors present new measurements on the viscosity of the vapours of cyclohexane and of neopentane from near room temperature to 630 K and for densities to 4.8 kg m−3 and 0.069 mol 1−1.
Abstract: This paper presents new measurements on the viscosity of the vapours of cyclohexane and of neopentane from near room temperature to 630 K and for densities to 4.8 kg m−3 and 0.057 mol 1−1 (cyclohexane) and to 5.0 kg m−3 and 0.069 mol 1−1 (neopentane). Two all-quartz oscillating-disk viscometers with small gaps were used in the investigation. The data for cyclohexane and neopentane as well as earlier results for benzene show that the negative and positive values of the second viscosity virial coefficient Bη, dependent on temperature represent the normal behaviour for all substances. The experimental data on the three hydrocarbons are suitable for the further development of the Rainwater-Friend theory concerning the transport properties of moderately dense gases in respect to their temperature range and their limitation to the Lennard-Jones 12-6 potential.
TL;DR: In this paper, the gas viscosities of azeotropic mixtures were measured with an oscillating disk viscometer of the Maxwell type at 273.15-423.15 K up to 7.5 MPa.
Abstract: Gas viscosities of azeotropic mixtures R500 (dichlorodifluoromethane (R12)-1, 1-difluoroethane (R152a)), R 502 (chlorodifluoromethane (R22)-chloropentafluoroethane (R115)), and R503 (chlorotrifluoromethane (R13)-trifluoromethane (R23)) were measured with an oscillating disk viscometer of the Maxwell type at 273.15-423.15 K up to 7.5 MPa. Two empirical equations for the viscosities were obtained; one is for the atmospheric viscosities as a function of temperature, and the other is for the viscosities in the whole range of the present measurement as a function of temperature and density.
TL;DR: In this article, a new chromatographic method for characterization of polyamides and polyether-block-amide copolymers by Size Exclusion Chromatography (SEC) is presented.
Abstract: We report here a new chromatographic method for characterization of polyamides and polyether-block-amide copolymers by Size Exclusion Chromatography. First, it concerns absolute characterization of polyamide probes by classical light scattering and Ubbelohde viscometry measurements and the choice of narrow distribution standards to calibrate the GPC system. The GPC analysis of polyamides 6, 11, 12 and copolymers is based upon the dual detection refractometer/on-line continuous viscometer at 130°C using columns packed with cross-linked polystyrene gels, benzyl alcohol as mobile phase and polytetrahydrofuran standards for calibration. The main results are absolute average molecular weights and distribution curve, intrinsic viscosity and viscosity law. In addition, viscometric data produced evidence of long-chain branching occuring beyond a limiting molecular weight in some polyamide 12 samples.
TL;DR: In this article, the extensional viscometer developed earlier by the authors was refined and used to extend very dilute (50 ppm) solutions of polyacrylamide in distilled water.
Abstract: The extensional viscometer developed earlier by the authors was refined and used to extend very dilute (50 ppm) solutions of polyacrylamide in distilled water. A slender liquid filament was stretched by the use of a suction device, and this resulted in the spinning of the fiber. By varying the volumetric flow rate and the filament length, stretch rates in the 100–1000 s −1 range were easily obtained. The corresponding tensile stresses were very large, and these gave apparent extensional viscosities of the order of 200 P (20 Pa s). In contrast to this, the material functions in shear were difficult to measure, except for the shear viscosity which showed pronounced shear thinning. It was found that all the measurements, in shear as well as extension, could be explained based on the four constant Johnson-Segalman constitutive equation.
TL;DR: In this article, the axial and tangential velocity fields are surveyed in a pipe for the determination of eddy viscosity, and an empirical relationship is suggested to determine the eddiness as a function of Reynolds number and swirl number.
Abstract: Prediction of heat transfer coefficient for swirling flows can be made provided the values of the eddy viscosity are available. In the present work the axial and tangential velocity fields are surveyed in a pipe for the determination of eddy viscosity. The data thus obtained were utilised to determine the influence of the axial Reynolds number and swirl number on the eddy viscosity. An empirical relationship is suggested to determine the eddy viscosity as a function of Reynolds number and swirl number.
Patent•
22 Aug 1988TL;DR: In this paper, a transient flow capillary viscometer is provided for establishing a measure of the viscosity of a highly viscous test fluid, which relies upon inducing a step change in the differential pressure across the ends of the capillary tube, which causes fluid to flow therein.
Abstract: A transient flow capillary viscometer is provided for establishing a measure of the viscosity of a highly viscous test fluid. More particularly, a capillary tube filled with the test fluid is provided. The viscometer relies upon inducing a step change in the differential pressure across the ends of the capillary tube, which causes the fluid to flow therein. The resultant decrease in pressure drop as a function of time, i.e. the half-life of pressure decay, is monitored and provides an approximate measure indicative of the viscosity of the fluid.
01 Jan 1988
TL;DR: A high pressure viscometer has been constructed for use over a wide range of temperatures and pressures, including near-critical and supercritical conditions as discussed by the authors, where an aluminum cylinder falls through a tube containing a stationary column of fluid, enabling viscosities to be determined from terminal velocity measurements.
Abstract: A high pressure viscometer has been constructed for use over a wide range of temperatures and pressures, including near-critical and supercritical conditions. An aluminum cylinder falls through a tube containing a stationary column of fluid, enabling viscosities to be determined from terminal velocity measurements. Preliminary results are presented on the search for an additive which can enhance the viscosity of carbon dioxide when present in low (less than 1%) concentrations.
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01 Jul 1988
TL;DR: In this article, rotary viscometry has been used to investigate the influence of the conditions of deformation of foams on their degree of dispersion, characterized by dilatant and thixotropic properties.
Abstract: Rotary viscometry has been used to investigate the influence of the conditions of deformation of foams on their degree of dispersion. The foams are characterized by dilatant and thixotropic properties: the presence of an effective viscosity maximum at certain shear rates; the significant influence of the coaxial clearance on the effective viscosity.
TL;DR: In this paper, the effect of solution viscosity on ultrafiltration flux was studied and it was found that the relationship between ultrafiltrate flux J and inverse of solution V 1 ǫ is not exactly linear but depends on solution V 2.