Showing papers on "Viscometer published in 1993"
TL;DR: In this article, experimental measurements were reported for the dynamic viscosity and the density of four binary mixtures of n-butylamine with methanol, ethanol, 1-propanol, and 1-butanol.
Abstract: Experimental measurements are reported for the dynamic viscosity and the density of the four binary mixtures of n-butylamine with methanol, ethanol, 1-propanol, and 1-butanol. The measurements were conducted at 25 o C and in a pressure range from atmospheric to 720 bar for the dynamic viscosity and from atmospheric to 300 bar for the density. The self-centering falling body viscometer used is described in detail. Calculated excess volumes, compressibilities, and excess viscosities are also reported. The systems studied, besides self-association, exhibit very strong cross-association due to the strong hydrogen bonding between the hydroxyl and the amine groups
113 citations
TL;DR: In this article, the coexistence curve and physical property data (densities, viscosities, surface tensions, and interfacial tensions of the equilibrated coexisting phases) for 2,6-lutidine+water have been determined over the range 34-60 o C, and the density and viscosity differences calculated.
Abstract: The coexistence curve and physical property data (densities, viscosities, surface tensions, and interfacial tensions of the equilibrated coexisting phases) for 2,6-lutidine+water have been determined over the range 34-60 o C, and the density and viscosity differences calculated. The compositions were determined through the refractive index at 22 o C, densities by a commercial electronic oscillating U-tube, viscosities by a U-tube viscometer, surface tensions by a du Nouy ring method, and interfacial tensions by a spinning drop interfacial tensiometer
91 citations
TL;DR: Flow of various bodily fluids, including pus, is according to Poiseuille's law, confirming that for more viscous fluid, larger catheters provide more rapid drainage.
Abstract: An in vitro study was performed to determine the range of flow times of different bodily fluids through catheters of different diameters and to test the hypothesis that urokinase might decrease the viscosity of purulent material.A standard viscometer was used to measure the viscosities of water, blood, pseudocyst fluid, purulent material, and purulent material with admixed urokinase. For each fluid, Poiseuille's law was used to calculate the kinematic viscosity, from which theoretical drainage times through seven different sizes of catheters were calculated. These theoretical times were compared with the actual measured values to verify that flow was according to Poiseuille's law.The calculated kinematic viscosities (in 10(-6) stokes) were as follows: water, 0.695 +/- 0.006; pseudocyst fluid, 2.185 +/- 0.008; blood, 3.001 +/- 0.049; abscess fluid without urokinase, 5.729 +/- 0.064; and abscess fluid with urokinase, 4.416 +/- 0.070. The viscosity of abscess fluid decreased by 23% with the addition of uroki...
82 citations
TL;DR: The development and use of the centrifugal force diamond anvil cell viscometer described here extends the range of continuous high-pressure viscosity measurements on a single sample to greater than 10 9 cP at pressures which can exceed 10 GPa.
Abstract: The development and use of the centrifugal force diamond anvil cell viscometer described here extends the range of continuous high-pressure viscosity measurements on a single sample to greater than 10 9 cP at pressures which can exceed 10 GPa. Measurement of the high-pressure viscosity of the common glass-forming liquids glycerol, 1,2-propanediol, methanol, and dibutyl phthalate over extreme compression ranges demonstrates the accuracy of the technique. A simple free volume model fits these data remarkably well over 9 decades in viscosity and at compressions of up to 44%. Extrapolation of this data leads to estimated glass transition pressures in good agreement with independent experimental determinations
69 citations
Patent•
05 Jan 1993TL;DR: In this paper, an approach for hydrating a particulated polymer and producing a well treatment gel includes a mixer for spraying the polymer with water at a substantially constant water velocity and at a very high water spray pattern at all flow rates of the water.
Abstract: Apparatus and method of hydrating a particulated polymer and producing a well treatment gel includes a mixer for spraying the polymer with water at a substantially constant water velocity and at a substantially constant water spray pattern at all flow rates of the water. A centrifugal diffuser is connected to the mixer for receiving the mixture, centrifugally diffusing the motive energy of the mixture, and hydrating the mixture into a gel. A centrifugal separator and constant velocity jet pump may be connected between the mixer and the centrifugal diffuser. A dilution valve is connected to the discharge of the centrifugal diffuser for mixing water with the gel at a substantially constant mixing energy at all flow rates of the gel and producing a diluted gel. A viscometer may be connected to the discharge of the dilution valve for measuring the viscosity of the diluted gel and regulating the flow of gel from the centrifugal diffuser to the dilution valve in order to control the viscosity of the diluted gel.
68 citations
TL;DR: In this paper, the authors examined the fully developed flow of a generalized fluid of second grade between heated parallel plates, due to a pressure gradient along the plate, and obtained the solution for the case when the temperature changes only in the direction normal to the plates for the two most commonly used viscosity models.
Abstract: We examine the fully developed flow of a generalized fluid of second grade between heated parallel plates, due to a pressure gradient along the plate. The constant coefficient of shear viscosity of a fluid of second grade is replaced by a shear dependent viscosity with an exponentm. If the normal stress coefficients are set equal to zero, this model reduces to the standard power-law model. We obtain the solution for the case when the temperature changes only in the direction normal to the plates for the two most commonly used viscosity models, i.e. (i) when the viscosity does not depend on temperature, and (ii) when the viscosity is an exponentially decaying function of temperature.
65 citations
Patent•
21 Oct 1993
TL;DR: In this paper, a viscometer for improved sanitary measurement of the viscosity of industrial fluids is presented, which includes two adjacent parallel flow channels having relatively flat inner surfaces, and a differential pressure element is mounted between them to sense the differential pressure between the fluid flow of the two channels.
Abstract: A viscometer for improved sanitary measurement of the viscosity of industrial fluids. The present invention provides a viscometer integral with a flow meter or a viscometer than can be mounted onto an existing flow meter. The viscometer includes two adjacent parallel flow channels having relatively flat inner surfaces. A differential pressure element is mounted between the adjacent flow channels to sense the differential pressure between the fluid flow of the two channels. The differential pressure is input along with the mass flow rate and fluid density to calculate the fluid viscosity.
62 citations
Journal Article•
TL;DR: In this article, the viscosity of NarSinO, liquid at high pressure is estimated from the O diffusivity data using the Eyring relationship, which has been shown to be applicable to polymerized silicate liquids up to at least 2GPa.
Abstract: couples were prepared from glass starting materials with one-half of the sample enriched in r8O and the other half containing the natural abundance (-0.2 wto/o). Following exchange ofO across this diffusion couple at high temperature and pressure, '8O concentration profiles were analyzed using an ion microprobe. O diffusivities were obtained by fitting the equation for diffusion between two semi-infinite bodies to the concentration profiles. At 1825'C, O diffusivity increases continuously from I x l0-'0 m2ls at 2.5 GPato 4 x l0-'0 m2ls at l0 GPa, yielding an activation volume of -3.3 t 0.4 cm3/mol. This trend is consistent with the results of molecular dynamics calculations and may be related to an increase in fivefold-coordinated Si with increasing pressure. The viscosity of NarSinO, liquid at high pressure is estimated from the O diffusivity data using the Eyring relationship, which has been shown to be applicable to polymerized silicate liquids up to at least 2GPa. Estimated viscosities at 1825'C and high pressure are consistent with an extrapolation of viscosity data obtained at I bar by other techniques and suggest a viscosity decrease of -0.8 log units from I bar to 10 GPa. The results also suggest that the activation energies for viscous flow and O diffusivity decrease significantly in the pressure range I bar to 4 GPa. Provided the validity of the Eyring relationship can be established, these results demonstrate that melt viscosities can be estimated from O-diffusion experiments up to at least l0 GPa. In contrast, measurements using falling-sphere viscometry are extremely difficult at such conditions because of low viscosities and small sample size. INrnonucrroN For this reason, the effects ofpressure on transport propertres are more difficult to predict from simple kinetic Knowledge of the transport properties of silicate liq- theory for silicate liquids than for crystalline phases, and uids at high pressure is crucial for understanding mag- in general direct measurements are required. Although matic processes within the Earth. Experimental and the- viscosity and O diffusivity have been studied experimenoretical studies of silicate liquids have demonstrated that tally for a range of compositions, the maximum pressures pressure can have a major effect on both diffusivity and reached in these studies have been low (<2.5 GPa) comviscosity(Watson, 1979; Angell etal., 1982;Shimizuand pared with pressures in the Earth's mantle. The develKushiro, 1984; Scarfe et al., 1987). Such pressure effects opment of the multianvil high-pressure apparatus now will be important in controlling processes such as melt makes it possible to greatly extend the pressure range of segregation and chemical equilibration of migrating melts such studies. in the Earth's mantle. A knowledge of transport proper- We present results of an experimental study of O selfties at high pressure is also necessary for understanding diffusion in NarSioOn liquid in the pressure range 2.5-10 the dynamics, evolution, and crystallization of a magma GPa. This composition was chosen primarily because ocean that may have formed during the early history of changes in the structure of NarSioOn glasses quenched at the Earth (e.g., Wetherill, 1990).
61 citations
TL;DR: In this article, the authors measured the viscosity of glycerol at pressures of up to 3 GPa using centrifugal-force viscometry in a diamond-anvil cell.
Abstract: As a liquid approaches its glass transition temperature Tg, its viscosity increases rapidly. The glass transition can be induced either by lowering the temperature through Tg or by increasing the pressure (and thereby the density) at constant temperature. The effect of temperature on viscosity is well studied, but the density dependence of viscosity close to Tg is less well understood. Here we report measurements of the viscosity of glycerol, one of the most widely studied glass-forming liquids, at pressures of up to 3 GPa using centrifugal-force viscometry in a diamond-anvil cell. We find that free-volume theory1,2, which ascribes an incom-pressible hard-sphere volume to the molecules, provides a good description of the viscosity over the entire pressure range (and by extrapolation, up to the glass transition at ∼5 GPa). We are thus able to predict the effect of pressure on Tg and on the glass fragility (the structural breakdown in the liquid close to the transition).
60 citations
TL;DR: In this paper, the authors reported new measurements of the viscosity of liquid R134a over the temperature range 235 to 343 K and pressures up to 50 MPa, with a maximum deviation of ± 0.3%.
Abstract: The paper reports new measurements of the viscosity of liquid R134a over the temperature range 235 to 343 K and pressures up to 50 MPa. The measurements have been carried out in a vibrating-wire viscometer calibrated with respect to the viscosity of several liquid hydrocarbons. It is estimated that the uncertainty in the viscosity data reported is ±0.6%. The data therefore have a lower uncertainty than that of earlier measurements of the viscosity of this environmentally acceptable regrigerant. The viscosity data have been represented as a function of density by means of a formulation based upon the rigid, hard-sphere theory of dense fluids with a maximum deviation of ±0.3%. This representation allows the present body of experimental data to be extended to regions of thermodynamic state not covered by the measurements.
51 citations
TL;DR: The accuracy and the usefulness of the MT90 (falling ball) viscometer is tested as an alternative to more expensive and sophisticated devices for physiological and clinical investigations and it is suggested that it is useful and accurate for physiology and clinical studies.
Abstract: Received 20.12.1992; accepted 16.4.1993) We tested the accuracy and the usefulness of the MT90 (falling ball) viscometer as an alternative to more expensive and sophisticated devices for physiological and clinical investigations. This instruments measures viscosity from the velocity of a ball falling through a syringe filled with less than 1 ml of blood or plasma at a shear rate of 1000 s-1, Le. the range of the so-called 'newtonian' behavior of blood. We postulated that this shear rate allows us to measure RBC rigidity in a completely disaggregated structure. Four indices of RBC rigidity derived from high shear rate viscometry were used: 1J45r (Le. blood viscosity at corrected hematocrit 45% divided by plasma viscosity); 'Tk' (Dintenfass); 'k' (Quemada); 'IJ(RBC), (Breugel and coiL). All were strongly correlated to each other (r=0.98 p<0.01) and easily detected in vitro rigidification of RBCs with (a) ionophore A23187 (10-4M); (b) heating at 56·C during 10 min; (c) 30 min incubation in hypercalcemic-hyperosmolar buffer, when used together with Hanss' hemorheometre. At this shear rate, modifications of blood viscosity induced by changes (within a physiological range) of hematocrit and RBC rigidity were correctly described by both Quemada's and Dintenfass's equations for blood viscosity. 'k' values given by the equation of Quemada at this shear rate correlated with RBC rigidity indices calculated with the Carri-Med rheometer using both Quemada's and Wang's equations. Correlations between these indices of rigidity and those given by the hemomeometre were found only for in vitro experiments of RBC stiffening, while in clinical situations viscometric and hemorheometric indices gave rather different results. The coefficient of variation for viscometric measurements was 2% (plasma viscosity) and 3% (blood viscosity). We conclude that this viscometer gives results consistent with other methods. We suggest that it is useful and accurate for physiological and clinical studies.
TL;DR: In this paper, an aqueous extract from konjac flour was dried, milled and redispersed in water, prior to its characterization by viscometry and rheometry.
TL;DR: In this article, a new high-pressure, high-shear stress viscometer has been developed with a pressure capability of 300 MPa and shear stress of 26 MPa for shear.
Abstract: A new high-pressure, high-shear stress viscometer has been developed with a pressure capability of 300 MPa and shear stress of 26 MPa for shear which is essentially isothermal in the context of the...
TL;DR: In this article, the authors reported new measurements of the viscosity of R32 and R125, in both the liquid and the vapor phase, over the temperature range 220 to 343 K near the saturation line.
Abstract: This paper reports new measurements of the viscosity of R32 and R125, in both the liquid and the vapor phase, over the temperature range 220 to 343 K near the saturation line. The measurements in both liquid and vapor phases have been carried out with a vibrating-wire viscometer calibrated with respect to standard reference values of viscosity. It is estimated that the uncertainty of the present viscosity data is one of 0.5–1%, being limited partly by the accuracy of the available density data. The experimental data have been represented by polynomial functions of temperature for the purposes of interpolation.
TL;DR: In this article, the shear viscosity coefficients of saturated and compressed liquid 1,1, 1, 2-tetrafluoroethane (R134a), 2,2-dichloro-1,1-1-trifluoro-ethylene (R123), and 1, 1-fluoro-1fluoroethylane(R141b) were measured with a torsional crystal viscometer at temperatures between 170 and 320 K and at pressures up to 30 MPa.
TL;DR: In this article, the shear viscosities of saturated and compressed fluid 1-chloro-l, 2,2,2-2-tetrafluoroethane (R124) and pentafluoroethylene (R125) have been measured with two torsional crystal viscometers at temperatures between 120 and 420 K and at pressures up to 50 MPa.
Abstract: The shear viscosities of saturated and compressed fluid 1-chloro-l,2,2,2-tetrafluoroethane (R124) and pentafluoroethane (R125) have been measured with two torsional crystal viscometers at temperatures between 120 and 420 K and at pressures up to 50 MPa. At small molar volumes, the fluidity (reciprocal viscosity) increases linearly with molar volume at fixed temperature and weakly with temperature at fixed volume. We have described this behavior with simple empirical equations and have compared the data of Shankland and of Ripple with them. The data of Ripple are in good agreement with our data for both fluids.
TL;DR: In this paper, the authors used torsional deformation to study the shear stress relaxation in haplogranite melts and found that the relaxation spectrum has an asymmetrical form which can be fitted by a stretched exponent with parameter s ~ 0.5.
Abstract: Shear stress relaxation in haplogranite melts has been investigated using torsional deformation. Sinusoidal shear strains of small amplitude (10_3-10~5) have been generated over 4 orders of magnitude of strain rate and a wide range of temperatures. The viscoelastic behavior of the investigated melts can be characterized in terms of the complex shear modulus, the complex shear viscosity, and the internal friction. With addition of B, P, F to a haplogranite melt, the relaxation spectrum becomes broader, skewing further towards shorter relaxation times. Thus, the solution of volatiles in highly polymerized melts leads to a broadening, in frequency-temperature space, of the viscoelastic region which separates liquid behavior from glassy behavior. The relaxation spectrum of pure haplogranite melt has an asymmetrical form which can be fitted by a stretched exponent with parameter s ~0.5. The boron-containing melts are characterized by s~0.4, the phosphorus- and fluorine-containing melts yield s < 0.4. The unrelaxed shear modulus of the liquids obtained at high frequencies and low temperatures are in agreement with the results of new high-frequency (20 MHz) ultrasonic measurements performed at room temperature. The additions of boron, phosphorus, and fluorine all result in decreases in the unrelaxed shear modulus. The relaxed (or Newtonian) shear viscosity obtained from this study at low frequencies and high tempera tures compares well with the data obtained by micropenetration viscometry on the same samples. The present low-temperature viscosity data together with high-temperature concentric cylinder viscometry measurements describe an Arrhenian relationship for all investigated compositions in the temperature range of 650-1650 °C. The activation energy of viscous flow decreases with B, P and F content.
TL;DR: In this paper, the authors measured the viscosity and density of six binary mixtures of HFC-134a with glycols in the temperature range from 273 to 333 K.
Abstract: Liquid viscosity and density of six binary mixtures of HFC-134a with glycols [ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (400), and polypropylene glycol (2000)] have been measured in the temperature range from 273 to 333 K. The viscosity was measured by a rolling-ball viscometer calibrated with standard liquids of viscosities and densities (JS5, JS10, JS20, and JS50). The density was measured with a glass pycnometer. The uncertainties of the measurements were estimated to be less than 3.4 % for viscosity and 0.04 % for density, respectively. An equation is given to represent the obtained viscosity values as a function of weight fraction and temperature.
TL;DR: In this article, the authors compared the predictions of a non-Linear Maxwell model, in which the viscosity coefficient is assumed to depend on the instantaneous structural state of the material, compared to measurements on normal blood.
TL;DR: In this article, the authors used a tube flow viscometer equipped with three tube sizes and a concentric cylinder viscometers (Rheometrics pressure Rheometer) to evaluate the rheological properties of four different viscous crude oil emulsions.
TL;DR: In this paper, the authors proposed a reciprocal asymptotic isoviscous pressure α* as a replacement for the initial pressure viscosity coefficient α0 based on the Weibull pressure transformation.
Abstract: The classical elastohydrodynamic film thickness solution which assumes a purely exponential variation of viscosity with pressure requires a pressure-viscosity coefficient. In general, liquid lubricant viscosity varies with pressure such that the local pressure-viscosity coefficient is a function of pressure, making the determination of the pertinent parameter for film thickness difficult. Blok proposed a reciprocal asymptotic isoviscous pressure α* as a replacement for the initial pressure viscosity coefficient α0 based on the Weibull pressure transformation. The pressure-viscosity characteristics of seven liquid lubricants were measured with a falling body viscometer to pressure of 0.76 GPa and α0 and α* were calculated. Viscosity and glass transition results were applied to a model in current usage. The EHD film thickness was measured using interferometry supported by the measurement of the refractive index at elevated pressure. The reciprocal asymptotic isoviscous pressure was found to be more correct ...
TL;DR: In this article, the viscosity coefficient of the refrigerant R152a (1,1-difluoroethane) has been measured along the saturation line both in the saturated liquid and in saturated vapor.
Abstract: The viscosity coefficient of the refrigerant R152a (1,1-difluoroethane) has been measured along the saturation line both in the saturated liquid and in the saturated vapor. The data have been obtained every 10 K from 243 up to 393 K by means of a vibrating-wire viscometer using the free damped oscillation method. The density along the saturation line was calculated from the equation of state given by Tamatsu et al. with application of the saturated vapor-pressure correlation given by Higashi et al. An interesting result is that in the neighborhood of the critical point, the kinematic viscosity of the saturated liquid seems to coincide with that of the saturated vapor. The results for the saturated liquid are in satisfying agreement with those of Kumagai and Takahashi and of Phillips and Murphy. A comparison of the saturatedvaport data with the unsaturated-vapor data of Takahashi et al. shows some discrepancies.
TL;DR: In this paper, the authors measured saturated liquid viscosities and densities on environmentally acceptable HCFCs, using a capillary viscometer and a glass pycnometer in the temperature range from 273 to 353 K. The uncertainty in the measurement of viscosity is estimated to be 5% based on the comparison of the present data with those in the literature for HCFC-141b.
Abstract: Measurements of saturated liquid viscosities and densities were performed on environmentally acceptable hydrochlorofluorocarbons (HCFCs), CH3CCl2F (HCFC-141b), CH3CClF2 (HCFC-142b; only for viscosity), CF3CF2CHCl2 (HCFC-225ca), and CClF2CF2CHClF (HCFC-225cb), using a capillary viscometer and a glass pycnometer in the temperature range from 273 to 353 K. The uncertainty in the measurement of viscosity is estimated to be 5% based on the comparison of the present data with those in the literature for HCFC-141b. An equation is given to represent our saturated liquid viscosity data as a function of temperature.
TL;DR: In this paper, a new temperature-dependent viscosity equation based on the Carreau model is introduced; this model takes into account the effects of shear-thinning non-Newtonian characteristics and temperature on the viscosities of the polyacrylamide solution.
TL;DR: A canal surface viscometer has been designed and constructed to measure the inplane steady shear viscosity (ηs) of monolayers at the air/water interface.
Abstract: A canal surface viscometer has been designed and constructed to measure the in‐plane steady shear viscosity (ηs) of monolayers at the air/water interface The technique involves forcing a monolayer to flow through a canal to another monolayer under a constant surface pressure gradient and measuring the area flow rate The instrument incorporates a feedback electronic system to maintain the surface pressure on each side of the canal to about 01 dyn/cm during monolayer flow The canal design is modified from that of an earlier design in the literature to eliminate artifacts that give rise to systematic variabilities as reported Specifically, it is demonstrated that the glass‐paraffin canal design used in the past produces ill reproducible results in contrast to an all Teflon canal, which gives rise to consistently reproducible surface viscosity data A comparison is made between ηs values obtained from the canal viscometer and the knife‐edge ring surface viscometer, another technique reported in the liter
TL;DR: In this paper, a capillary-flow gas viscometer has been used to measure the shear viscosities of gaseous HCFC 123 (2,2-dichloro-1,1-1-trifluoroethane), HCFC 124 (2-chloro- 1,1, 1, 2-tetrafluoro-ethane) and HFC 134a (1 1.1 MPa relative to a nitrogen standard) at pressures up to 0.15-363.
Abstract: A capillary-flow gas viscometer has been used to measure the shear viscosities of gaseous HCFC 123 (2,2-dichloro-1,1,1-trifluoroethane), HCFC 124 (2-chloro-1,1,1,2-tetrafluoroethane) and HFC 134a (1,1,1,2-tetrafluoroethane) at pressures up to 0.1 MPa relative to a nitrogen standard. The experimental temperature ranges were within the limits imposed by the boiling points and decomposition temperatures of the samples, the precise ranges being 308.15–363.15 K for HCFC 123, 283.15–403.15 K for HCFC 124 and 308.15–403.15 K for HFC 134a. The flow times were corrected for small temperature drifts, kinetic-energy and gas-imperfection effects, and slip flow. Pressure conditions were chosen such that curved-pipe flow and turbulence effects were negligible. The accuracy of the viscometer, in terms of its function and our experimental procedure, was confirmed by measuring the relative viscosities of nitrogen and argon. These results were found to be within 0.1% of published data. Our measurements of the viscosity of HFC 134a are shown to agree to a limited degree with other workers' results within combined experimental uncertainty. Our measurements for HCFC 123 agree within experimental uncertainties with other measurements, and no other measurements of HCFC 124 viscosity have been found. Within the framework of the rigorous Chapman–Enskog kinetic theory of gases, we calculate approximate self-diffusion coefficients and hard-sphere collision diameters for the molecules. An analysis of HFC 134a and HCFC 123 viscosities by the extended law of corresponding states allows us to calculate the well depths of the intermolecular interactions using collision diameters suggested by Nabizadeh and Mayinger (Proc. 12th European Conference on Thermophysical Properties, 1990). The use of Schramm, Hauck and Kern (Ber. Bunsenges. Phys. Chem., 1992, 96, 745) of a Stockmayer potential-energy function is discussed. Finally, an application of the Mason–Monchick approximation to the Stockmayer function is used to calculate the percentage effect of the dipole moments on the collision integrals.
TL;DR: In this paper, a simple method of deriving weighting factors for fitting local intrinsic viscosity calibration curves was shown to greatly improve the precision of calculated molecular weight distributions, and the problem of reliably extrapolating the fitted curves to allow for differences in sensitivity among detectors has yet to be examined.
Abstract: Five different types of calibration curve currently used in size exclusion chromatography-differential viscometer (SEC–DV) systems were identified and their use summarized. A simple method of deriving weighting factors for fitting local intrinsic viscosity calibration curves was shown to greatly improve the precision of calculated molecular weight distributions. The problem of reliably extrapolating the fitted curves to allow for differences in sensitivity among detectors has yet to be examined. With regard to Mark—Houwink constants, a method of fitting data from the SEC–DV system to obtain more statistically sound values was derived. For the data used here, the new method involves fitting a plot of logarithm of the local intrinsic viscosity of the sample vs. logarithm of the universal calibration curve parameter, Ji. Results for the data obtained appeared only slightly more precise than those for the traditional method. However, the new method promises improved reliability. © 1993 John Wiley & Sons, Inc.
Journal Article•
TL;DR: In this paper, rotational viscometers were used for low-shear measurements and a capillary viscometer for high shear measurements, and the viscosity data were combined to generate a single flow curve for each formulation covering shear rates from 1s -1 to 1,000,000s −1.
Abstract: Coating rheology data were collected using rotational viscometers for low-shear measurements and a capillary viscometer for high-shear measurements. The viscosity data were combined to generate a single flow curve for each formulation covering shear rates from 1s -1 to 1,000,000s -1 . This flow curve was fitted with a five-parameter model using an extension of the Cross equation to include dilatancy at high shear rates. This rheology model was incorporated into a computational fluid dynamics (CFD) simulation of a short-dwell coater whichh took into consideration differences in coater geometry. The blade pressures calculated from the computer model were compared with pilot coater data for the same formulation.
TL;DR: In this article, the surface canal viscometry technique was used to determine the inplane steady shear viscosity of monolayer assemblies of several amphiphilic molecules at the air/water interface.
Abstract: The surface canal viscometry technique was used to determine the in‐plane steady shear viscosity of monolayer assemblies of several amphiphilic molecules at the air/water interface. By varying the subphase viscosity by a factor of about 2.5 without affecting its surface activity, we were able to deduce the surface viscosity, which is independent of the subphase viscosity, only after correcting for the hydrodynamic coupling as prescribed by the theory of Harkins and Kirkwood. Alternatively, the subphase shear viscosity has been correctly deduced from the observed area flow rate through a canal in the limit of a vanishingly small surface viscosity where the flow rate now depends solely on the subphase viscosity through hydrodynamic coupling. By testing in these two limits, we evaluated and confirmed for the first time the validity of the hydrodynamic coupling between the monolayers and the subphase, as proposed by the theory of surface viscous flow of Harkins and Kirkwood.
TL;DR: In this article, preliminary measurements of the viscosity of liquid water along two isotherms as a function of pressure up to 32 MPa have been performed with a vibrating-wire viscometer especially modified for the purpose.
Abstract: The paper reports new, preliminary measurements of the viscosity of liquid water along two isotherms as a function of pressure up to 32 MPa. The measurements have been performed with a vibrating-wire viscometer especially modified for the purpose. The instrument has been calibrated with respect to the viscosity of water at a pressure of 0.1 MPa and a temperature of 293.15 K, for which an accurate reference value is available. With due regard to the precision of the determination of individual quantities and the accuracy of the calibration data, it is estimated that the accuracy of the present results is one of ±0.3% under all conditions.