Showing papers on "Viscometer published in 1969"

Influence of deformability of human red cells upon blood viscosity.

Abstract: The viscosity of blood at high rates of shear is unusually low compared to other suspensions of similar concentration. The underlying mechanisms were studied by rotational viscometry, red cell filtration, viscometry of packed cells and direct microscopic observation of red cells under flow in a transparent cone plate viscometer. Deformability of red cells was altered osmotically or abolished by aldehyde fixation. The normal red cells under isosmotic conditions passed easily through filter pores (5 to 14 µ diameter). After osmotic crenation, deformability of cells in pore flow was reduced. Normal cells were deformed into a variety of shapes at high rates of shear, while crenated cells tumbled undeformed. Suspensions of these normal cells showed more pronounced shear thinning (reduction of viscosity with increasing shear rate) than suspensions of crenated cells. Suspensions of rigid cells showed greatly increased viscosity and a shear thickening as a function of shear rate and shear time. The physiological deformability is of critical importance to blood flow at high rates of shear. This is possible through a fluid transition of the erythrocyte caused by a rotation of the membrane with and around the cell contents. This phenomenon is the prime cause of the progressive reduction in viscosity with increasing shear.

High‐Temperature Viscosity Ratios for Hydrogen, Helium, Argon, and Nitrogen

Abstract: The temperature dependency of the coefficient of viscosity relative to its value at 283°K has been determined for hydrogen, helium, argon, and nitrogen at atmospheric pressure. The method used is a variation of the usual capillary viscometry scheme in that no attempt is made to obtain absolute viscosity values. The measurements provide the ratio of the viscosity of a gas at temperature T to its viscosity at the reference temperature, 283°K. The value of T ranges from 1100°K to 2150°K and is measured by a disappearing filament pyrometer. In this relative method there is cancellation of most noncontrolled experimental variables so that the measurements are of high reproducibility, ±0.1%, and apparently accuracy, ±0.4%, is limited only by the uncertainties in the international temperature scale in the optical pyrometer range. These results are higher by 3%‐8% compared with the results of previous workers. However, extrapolation of lower‐temperature viscosity measurements by Kestin and Leidenfrost, and more recently by DiPippo, gives excellent agreement with the values reported here.

Viscosity of Nitrogen, Helium, Hydrogen, and Argon from − 100 to 25°C up to 150–250 atm

Abstract: The range of a previously developed capillary‐flow viscometer has been extended to − 100°C, and the techniques of obtaining and determining the attainment of steady state have been improved. The viscosities of nitrogen, helium, hydrogen, and argon have been measured by an absolute method from − 100 or − 90° to 25°C and up to 150–175 atm (250 atm for N2 at 25°C). The accuracy is estimated to be 0.1%–0.2%, but is somewhat worse for Ar at − 100°C. A number of empirical and theoretical analyses of the viscosity–density dependence have been made; the evidence is inconclusive as to the presence of a logarithmic term in the density expansion. Correlations of the second and the third virial coefficients of viscosity have been made.

Viscosity and Density in Molten BeF2–LiF Solutions

Abstract: The viscosity of the molten salt system, BeF2–LiF, was determined with a coaxial‐cylinder viscometer. The concentration range studied was 36–99 mole % BeF2, each composition being measured over a 200° temperature interval within over‐all limits of 376°–967°C. The viscosity isotherms exhibit an exponential decrease in viscosity with increasing LiF concentration; the decreases are attributed to the rupturing of fluoride bridges in the BeF2 network structure. Each composition displayed Arrhenius behavior (Eη, energy of activation for viscous flow, was independent of temperature). Eη decreased with LiF concentration in a way that paralleled the decreases in the analogous systems, SiO2–alkaline‐earth oxide. Densities were measured between 50 and 100 mole % BeF2. From these measurements and other density determinations in BeF2–LiF, it was found that the molar volumes were additive. Volume expansivity, however, increases markedly with increasing LiF concentration. The decrease of Eη with LiF content in this syst...

Interfacial Effects on the Viscosity of a Nematic Mesophase

Abstract: The effects of interfacial orientation on the viscosity of nematic p-azoxyanisole have been studied. Viscosity was measured in four glass capillary tube viscometers with diameters ranging from 78μ to 516μ. The surfaces of the capillaries were subjected to two standardized pretreatmenta—acid cleaning or acid cleaning followed by rubbing with a fiber—in order to produce different interfacial orientations. Both treatments resulted in non-Newtonian viscosity behavior and a dependence of viscosity on tube diameter not in agreement with that predicted for a homogeneous fluid. However, it was found that the treatment of the interface had a profound effect on viscosity. Non-Newtonian viscosity and diameter effects were much more striking in the caw of interfaces subjected to acid cleaning only. The significance and implications of these findings is discussed.

Flow properties of suspensions with high solids concentration

Abstract: Equations were developed for evaluating the laminar flow behavior of high-solids suspensions from the physical properties of the liquid and solid components. A technique was developed for calculating suspension flow rates as a function of pressure drop. The technique is applicable to the design of pipe lines. Flow measurements were made in pipe-line viscometers of a unique design that minimized entrance and exit effects. Experimental flow data were obtained for suspensions consisting of nickel, alumina, copper, or glass solids in sodium, xylene, or glycerine vehicles with solids concentrations of 28 to 55 vol. %. The basis for the correlation of the data was an analytical investigation of the flow behavior that considered the particle-particle interaction that takes place in a settled suspension. The correlation equations fit all systems investigated. They take into account the effects of liquid viscosity, liquid and solid densities, particle size, size distribution, particle surface area, volume fraction of solids in the suspension, and volume fraction of solids at maximum settled conditions.

Viscosity Measurements on Liquids to Pressures of 60 kbar

Abstract: A rudimentary capillary‐type viscometer for measuring viscosities between 103 and 1010 poise at high pressures is described. Measurements are reported on petroleum ether to 57 kbar where the viscosity is approximately 1010 poise and on a 1:1 mixture of n‐pentane‐isopentane to 54 kbar where the viscosity is approximately 106 poise. Measurement precision of the technique is a few percent, but uncertainty in absolute determination at maximum pressure is only within a factor of two. Viscous stresses are shown to decay exponentially with time even at the highest pressures, and no effects of residual stress are observed.

End effects and particle migration effects in concentric cylinder rheometry

Abstract: End corrections for concentric cylinder viscometers are shown to depend on the properties of the fluid tested and are often much larger for non-Newtonian than for Newtonian fluids. The cylinder ends may contribute to the total torque an amount equal to 36% (compared with 16% for a Newtonian fluid) of the torque on the cylindrical surfaces in the case of the Rheomat 15 (system MS-A). Similar results have been obtained with another instrument but the corrections appear to be quite small for a Ferranti Portable viscometer. We have shown that during measurements on suspensions of spheres in viscoelastic non-Newtonian fluids in a concentric cylinder apparatus particle redistribution and migration effects occur which are similar to those reported earlier in cone-plate viscometry. The particles form rings and also migrate from the gap. The effect is not found with Newtonian fluids or with non-Newtonian fluids which do not produce a normal force when tested in a rheogoniometer.

Viscosity of sea water at moderate temperatures and pressures

Abstract: Results of observations of experiments with a rolling ball viscometer to determine the viscosity of 19.374‰ chlorinity IAPO standard sea water for the pressure range of 0 to 1406 kg/cm2 (gage) and temperatures from 0° to 30°C are given. Experimental results are compared with sea-water data reported in the literature and with previously reported data on the relative viscosity of pure water and show that: (1) the relative viscosity of sea water is always greater than that of pure water at comparable temperature and pressures; (2) the pressure of minimum relative viscosity of pure water decreases with the addition of an electrolyte; and (3) the activation energies of viscous flow of sea water decrease in a uniform manner with increasing pressure and temperature.

Influence of Deformability of Human Red Cells upon Blood Viscosity

Abstract: The viscosity of blood at high rates of shear is unusually low compared to other suspensions of similar concentration. The underlying mechanisms were studied by rotational viscometry, red cell filtration, viscometry of packed cells and direct microscopic observation of red cells under flow in a transparent cone plate viscometer. Deformability of red cells was altered osmotically or abolished by aldehyde fixation. The normal red cells under isosmotic conditions passed easily through filter pores (5 to 14 µ diameter). After osmotic crenation, deformability of cells in pore flow was reduced. Normal cells were deformed into a variety of shapes at high rates of shear, while crenated cells tumbled undeformed. Suspensions of these normal cells showed more pronounced shear thinning (reduction of viscosity with increasing shear rate) than suspensions of crenated cells. Suspensions of rigid cells showed greatly increased viscosity and a shear thickening as a function of shear rate and shear time. The physiological ...

Polyamides in solution. III. Viscometry of linear polycaprolactam

Abstract: The viscometric behavior of linear polycaprolactam has been studied in the absence of the electroviscous effect in aqueous solvents containing 85% and 64.5% formic acid and in trifluoroethanol, as a function of temperature and also under unperturbed conditions. Results are discussed in terms of the existing theories; in particular, the negative temperature coefficient of the intrinsic viscosity arises only from the variation of the expansion coefficient, the molecule in the unperturbed state being a normal random coil. The absence of aggregation and draining effects in the above solvents has been varified.

The Viscosity of Mesophases Formed by Cholesteryl Myristate

Abstract: This investigation provides the first reported viscosity measurements on cholesteryl myristate. Viscosities were measured as a function of both temperature and shear over temperatures corresponding to the isotropic liquid, the cholesteric mesophase, and the smectic mesophase. The myristate ester was chosen for study because its multiple phase transitions have been previously shown to be reproducible. The phases also persist over relatively long temperature ranges. The viscosity measurements were made at lower shear rates than previously reported for esters of cholesterol by using a Weissenberg Rheogoniometer. These are the first cone-and-plate viscosity measurements reported for any esters of cholesterol. The shear rates in this cone-and-plate viscometer are homogeneous and variable. The results show large breaks in viscosity behavior at the independently-measured thermodynamic transitions between the crystal, smectic, cholesteric, and isotropic states. Viscosities for the isotropic state are New...

Tracer Diffusion and Shear Viscosity in the Liquid–Liquid Critical Region

Abstract: Tracer diffusion coefficients of 3‐methylpentane in mixtures of 3‐methylpentane–nitroethane have been measured over the entire concentration range above the critical temperature in the range 0.04° ≤ T − Tc ≤ 9.5°C using the diaphragm cell technique. No anomaly was detected. The shear viscosity coefficients were measured across the concentration range for temperatures 0.004°C ≤ T − Tc ≤ 13.5°C by a capillary viscometer. The excess viscosities are compared with the predictions of the Fixman theory and the theory of Kadanoff and Swift. Very close to the critical point the weak divergence predicted by the second theory is observed while at larger values of ΔT Fixman's prediction seems adequate.

The Internal Viscosity of the Red Cell and the Structure of the Red Cell Membrane. Considerations of the Liquid Crystalline Structure of the Red Cell Interior and Membrane from Rheological Data

Abstract: In a series of experimental studies, carried out by means of rotational and microcapillary viscometers, it was possible to show that the viscosity of packed human cells, at haematocrits up to 98 pe...

Shear‐Rate Dependence of the Intrinsic Viscosity of Flexible Linear Macromolecules. II. Solvent Effect

Abstract: Measurements of the shear‐rate dependence of the intrinsic viscosity [η] were made on polystyrenes in several solvents, each of which differs in solvent power and solvent viscosity. Low‐shear capillary viscometers of the Maron–Belner type were used: shear stresses can be varied continuously from about 10 to a few tenths of a dyn/cm2, which is low enough to measure the zero‐shear intrinsic viscosity [η]0. The effect of excluded volume on the behavior of [η] / [η]0‐vs‐β (the generalized shear‐rate) curve was examined. The curves at and near the θ condition resemble that of Saito–Scheraga's prolate ellipsoid with axial ratio p = 2, and those in good solvents resemble that of p = 3 ellipsoid; the variation with solvent power is not so large as the theory of either Fixman or Chikahisa predicts. In the region of moderate to large β, the [η] / [η]0‐vs‐β curve decreases continuously with increasing β, as contrasted to the behavior of the ellipsoid, which levels off rather rapidly. The non‐Newtonian behavior is pr...

Surface rheological properties of foam stabilizers in nonaqueous liquids

Abstract: The rheological properties of foam stabilizers have been measured with an improved canal viscometer that provides absolute values of surface shear viscosity and yield strength. Studies conducted in room air confirmed previous reports of complex non-Newtonian film properties for oil soluble surfactants at the air-oil interface. Both shear and time dependent behavior were observed in which the apparent surface viscosity increased with decreasing rotational speed. Surface viscosities were low at all fresh interfaces but generally increased with the age of the surface over a period of several hours to several days. Experiments conducted in a controlled humidity environment have established that the phenomenon of aging in room air is due to adsorption of moisture from the gas by the surfactant film. Preliminary results indicate that the shear dependency of films in a high humidity environment can be approximated by a Bingham Plastic model which characterize their rheological behavior in terms of a Newtonian surface viscosity and yield value.

On the Viscosity of Liquid Selenium

Abstract: The viscosities of liquid selenium and partially-chlorinated liquid selenium were measured in the temperature range from 235°C to 305°C using an Ubbelohde-type tilting viscometer. The “intrinsic” viscosities, η0, were estimated by extrapolating the values of the viscosities, ηθ, of various rates of shear to a zero rate of shear. The “intrinsic” viscosities of the liquid selenium were estimated to be 20.18, 13.46, 9.11, 6.32, 3.67 and 2.30 poise at 235, 245, 255, 265, 285, and 305°C respectively. The viscosities of the chlorinated liquid selenium decreased with an increase in the chlorine content, but they varied discontinuously at a chlorine content of 0.0125% and then decreased linearly. The apparent activation energy for the viscous flow of the liquid selenium was estimated to be 17.9 kcal/mol. The apparent activation energies for the viscous flow of the chlorinated selenium varied discontinuously at a chlorine content of about 0.0125%, as in the case of the viscosity. The average-chain length of the se...

Viscosity Measurement of Water and Steam at High Temperatures and High Pressures

Abstract: Viscosity of water and steam was experimentally investigated in a wide range of temperatures up to 900°C and of pressures up to 1000 bar. In this investigation, a capillary viscometer was used in the closed circuit system with a high pressure injector and a mercury manometer. Measured results are compared with the standard values of the ICPS Skeleton Table (1964), and with experimental values of other investigations. A newly correlated equation represents experimental results within about 2% deviations.

The Effect of Pressure on the Non-Newtonian Behavior of Polymer Blended Petroleum Oils

Abstract: The shear dependence of polymer containing oils at elevated pressure was observed in a capillary-type viscometer and is reported Recoverable shear strain was not observed at elevated pressures but was observed at atmospheric pressure in the blends at the same shear stress The fluids examined included a paraffinic base oil (B), B plus four and eight weight percent methacrylate, B plus four weight percent styrene, a naphthenic base oil (F), and F plus four weight percent methacrylate

Viscosity of nitrogen, helium, hydrogen, and argon from - 100 to 25c up to 150-250 atmospheres

Abstract: : The range of a previously developed capillary-flow viscometer has been extended to -100C, and the techniques of obtaining and determining the attainment of steady state have been improved. The viscosities of nitrogen, helium, hydrogen, and argon have been measured by an absolute method from -100 or -90 to 25C and up to 150-175 atm (250 atm for N2 at 25C). The accuracy is estimated to be 0.1 - 0.2%, but is somewhat worse for Ar at -100C. A number of empirical and theoretical analyses of the viscosity-density dependence have been made; while inconclusive, the evidence tends not to support the presence of a logarithmic term in the density expansion. Correlations of the second and the third virial coefficients of viscosity have been made.

A modification to a variable shear stress air turbine viscometer

Abstract: A concentric cylinder air turbine viscometer previously described has been modified to extend the lower limit of shear stress to the region of 02 dyn cm−2. The effect of bearing pressure on calibration has been investigated.

A Low-Shear Titration Viscometer Suitable for Investigation of DNA and Other Polymers

Abstract: SUMMARY The viscosity of linear high-molecular-weight substances should be measured at sufficiently low shear gradients, e.g., with the aid of the ingenious Zimm-Crothers rotating-cylinder viscometer [1]. To investigate properties of nucleic acids or other polymers and their interaction with substances such as certain ions, dyes, etc., it proves useful to follow changes in polymer viscosity with increasing concentrations of the added interacting substance.

Physicochemical properties of N4 virus solutions. I. Viscosity--temperature behavior.

Abstract: The viscosity–temperature behavior of N4 virus solution was investigated by using a Zimm type viscometer The role of ionic strength (LiBr) and pH in the viscosity–temperature behavior was determined Supporting measurements of the sedimentation coefficient, infectivity, and optical density are presented The viscosity–temperature behavior generally includes a region of low viscosity, characteristic of the intact virus, followed, upon increasing temperature, by a rather abrupt increase of viscosity which corresponds to the ejection of native DNA from the protein shell, presumably through a suitable opening in the capside The viscosity remains constant upon further increase of temperature until a second abrupt increase is observed which is shown to correspond to the degradation of the empty protein shell (ghost) Finally, at a still higher temperature, denaturation of DNA occurs This sequence of events can be altered by changes in pH and ionic strength Increasing LiBr concentration reduces the temperature of ghost degradation and raises the temperature of DNA ejection and DNA de naturation It is suggested that polyelectrolyte effects play a controlling role in the ejection of native DNA and that the conformation of the latter within the protein shell is stabilized by a decrease of the electrostatic free energy due to the swamping effect of the co-ions

The Viscosities of Aqueous Solutions Containing Metal Complexes. II. trans -1,2-Cy clohexanediaminetetraacetato Complexes

Abstract: The viscosities of aqueous solutions containing metal chelate formed with trans-1,2-cyclohexanediaminetetraacetic acid (H4cydta) were measured with a Cannon-Fenske capillary viscometer. Measurements were made in a Shibata viscosity bath maintained at 25±0.01°C. The Jones-Dole viscosity B-coefficient of the cydta4− chelates is larger than that of the corresponding ethylenediaminetetraacetato (edta4−) chelates, as may be expected. The B-value of the Co (III) chelate [Co cydta]− is much smaller than that of any of the divalent metal cydta4− chelates studied. This fact, the same as in the case of the edta4− chelates, may indicate that the Co (III) chelate has a marked stable hexa-coordinated structure, while divalent metal chelates do not have such a stable hexa-coordinated structure as the Co (III) chelate.

Oscillating plate viscometry. Part 1.—Theoretical principles

Abstract: The equations of motion are derived and solved for the component parts of the oscillating plate viscometer.4 A linear relation √ηρ= Qδliq–K, is found at constant pressure, where η, ρ, are the viscosity and density of the liquid under test, δliq is the logarithmic decrement of the oscillations of a thin flat plate immersed in the liquid, and Q, K are apparatus constants. Both Q and K have been derived analytically, so that if desired the method may be employed without calibration using liquids of known viscosity; K is slightly pressure dependent. The derivations of Q and K involve certain approximations, but values of these can readily be computed to within 1 %; even better accuracy can be achieved using the viscometer as a comparative device.