Showing papers on "Viscometer published in 1976"
TL;DR: In this article, the effect of various thermomechanical treatments on the structure and rheological behaviour of Sn-15% Pb alloy in its solidifcation range was investigated using a concentric cylinder viscometer.
Abstract: The effect of various thermomechanical treatments on the structure and rheological behaviour of Sn-15% Pb alloy in its solidifcation range was investigated using a concentric cylinder viscometer. The apparatus was designed to permit wide ranges of cooling rates up to 25° C min−1 and shear rates up to 750 sec−1. Initially, the alloy was continuously sheared as it cooled from above the liquidus to a desired volume fraction solid. In one series of experiments, shear was stopped and the alloy quenched. In a second series, the alloy was held isothermally and subjected to various mechanical treatments. The size and morphology of primary solid particles during continuous cooling is influenced by shear and cooling rates and volume fraction of solid — faster cooling results in finer structures while increased rate of shear reduces the amount of entrapped liquid in individual particles. The viscosity of the slurry, at a given volume fraction solid, decreases with decreasing cooling rate and increasing shear rate. Exercising the full range of shear and cooling rates possible in the viscometer, the apparent viscosity of a 0.55 volume fraction solid slurry varied from 3 to 80P. The structure and viscosity of isothermally held slurries follow the same trends as slowly cooled slurries. However, their viscosity at a given volume fraction solid is consistently lower than that of continuously cooled slurries. The slurries are thixotropic and show a hysteresis loop phenomenon similar to other well known thixotropic systems. Measured areas of hysteresis loops increase with increasing volume fraction solid, initial viscosity and time at rest. The potential applications to improve existing or develop new metal-forming processes are being investigated in a variety of alloys with different solidifcation ranges and temperatures.
297 citations
TL;DR: In this article, a rotational type viscometer was employed for determination of the clotting power of milk-curdling enzymes through continuous monitoring of the viscosity of a milk-enzyme system.
59 citations
TL;DR: The control system was employed to successfully control the cell concentration but exhibited nonlinear behavior, and the viscometer and mixing unit were found to have first order dynamics.
Abstract: The apparent viscosity of baker's yeast suspensions was employed to control the cell concentration of the mixing of baker's yeast and distilled water. The apparent viscosity of baker's yeast was found to be a function of cell concentration and independent of the flow rate through the rotational viscometer. The viscometer and mixing unit were found to have first order dynamics. The open loop dynamics of the control system were nonlinear but could be linearized for small perturbations. The control system was employed to successfully control the cell concentration but exhibited nonlinear behavior.
26 citations
TL;DR: In this paper, a model relating the variation of the steady-shear melt viscosity of high-density polyethylene to the molecular weight distribution is applied toward predicting the steady shear elastic compliance, the first normal stress difference, and relaxation spectrum as a function of shear rate from the molecular distribution.
Abstract: An earlier model relating the variation of the steady-shear melt viscosity of high-density polyethylene to the molecular weight distribution is applied toward predicting the steady-shear elastic compliance, the first normal stress difference, and relaxation spectrum as a function of shear rate from the molecular weight distribution. The model envisions the cutting off of longer relaxation times as the shear rate is raised such that at any shear rate the molecular weights and their corresponding maximum relaxation times τm are partitioned into two classes; the relaxation times are partitioned into operative and inoperative states, depending on whether they are less than or greater than τc, the maximum relaxation time allowed at . Equations relating molecular weight and relaxation time to the steady-shear elastic compliance and viscosity are assumed valid at nonzero shear rates, except for the partitioning effect of shear rate. The shear rate dependence of the first normal stress difference and the steady-shear viscosity for polyethylene melts is successfully predicted over the range covered by the cone-and-plate viscometer. The assumed proportionality constant between τc and 1/ was determined to be 1.7. Using this relation, the maximum relaxation time at 190°C for a polyethylene molecule of molecular weight M is given by τm = 1.4 × 10−19 (M)3.33. Reasonable agreement has been obtained between the experimentally determined relaxation spectrum of a polyethylene melt and that predicted from the molecular weight distribution. The agreement is best at the longest relaxation times.
23 citations
TL;DR: In this article, a detailed analysis of the hemodynamic effects of red cell aggregates under defined flow conditions in vivo is presented, which shows that the conventional viscometry strongly underestimates the rheological differences between normal and pathologically intensified aggregation.
Abstract: The apparent viscosity of blood strongly increases at low shear in rotational viscometers, this phenomenon is based on the reversible formation of red cell aggregates. The magnitude of this increase strongly depends on the hematocrit value, on plasma viscosity and lastly on the microrheological properties of the aggregates. The independent measurement of the microrheological behavior and the effects on viscosity allows a detailed analysis of the hemodynamic effects of red cell aggregates under defined flow conditions in vivo. The comparative analysis shows that the conventional viscometry strongly underestimates the rheological differences between normal and pathologically intensified aggregation. Based on detailed analysis under defined flow conditions in vitro, the biological significance of viscometric results and the hemodynamic relevance of red cell aggregates are discussed.
23 citations
TL;DR: An indirect extrusion viscometer has been developed and tested on fluids of standard viscosity and results close to given standards have been obtained and errors in the procedure analyzed.
Abstract: An indirect extrusion viscometer has been developed and tested on fluids of standard viscosity. Results close to given standards have been obtained and errors in the procedure analyzed. Preliminary tests have shown that the developed apparatus will be suitable for following the viscosity changes during the setting of dental materials.
19 citations
TL;DR: The use of a conicylindrical viscometer in the measurement of blood viscosity has been investigated and the effect of packed cell volume and plasma fibrinogen concentrations on blood visCosity are described.
Abstract: The use of a conicylindrical viscometer in the measurement of blood viscosity has been investigated. Measurements at constant rates of shear and in situations of changing shear rate were performed. The practical details involved in blood measurement and the effect of packed cell volume and plasma fibrinogen concentrations on blood viscosity are described.
19 citations
TL;DR: In this article, a boundary layer solution is presented for fully developed laminar flow in a horizontal circular tube, assuming large Prandtl number and temperature-dependent viscosity and density.
Abstract: A boundary layer solution is presented for fully developed laminar flow in a horizontal circular tube, assuming large Prandtl number and temperature-dependent viscosity and density. The solution is given by Nu = C1 Ra1/4 , where C1 is a function of a nondimensional viscosity parameter and the heat flux boundary condition. The heat transfer predictions for large values of the viscosity parameter are 50 percent above the constant viscosity predictions. The present analysis is in good agreement with experimental data for water and ethylene glycol flowing in electrically heated tubes which approximate the boundary conditions assumed in the analysis.
19 citations
TL;DR: In this article, a high pressure linear variable differential transformer (LVDT) is used to detect the free fall of an unguided cylinder with a coaxial hole, the motion of which is optimized for maximum fall velocity, is recorded automatically by triggering the output of the LVDT, which is sensitive to changes in distance of 2 mu m.
Abstract: A description is given of a new high pressure viscometer which is capable of measuring viscosities up to 106 P s (107 Pa). The instrument consists essentially of a high pressure linear variable differential transformer (LVDT) which is used to detect the free fall of an unguided cylinder with a coaxial hole. The motion of the cylinder, the dimensions of which are optimized for maximum fall velocity, is recorded automatically by triggering the output of the LVDT, which is sensitive to changes in distance of 2 mu m. The sinker is returned to its starting position by inversion of the pressure vessel.
19 citations
TL;DR: The magnitude of the variation of synovial fluid viscosity with temperature is demonstrated, and it is suggested that routine clinical measurements be made at room temperature.
Abstract: A convenient and accurate way to measure the relative viscosity of synovial fluid is to use a white blood cell diluting pipette as a simple viscometer. The technique is reproducible with 2% accuracy and adds little to the time required for routine synovial fluid analysis. The magnitude of the variation of synovial fluid viscosity with temperature is demonstrated, and it is suggested that routine clinical measurements be made at room temperature. Clinical data confirm that a single viscosity measurement has little or no diagnostic value.
18 citations
Patent•
10 Sep 1976
TL;DR: In this article, a fluid having high and low viscosity components is introduced into the test region between a pair of bearing members which are biased for relative motion and which are characterized by at least one porous bearing surface.
Abstract: A fluid having high and low viscosity components is introduced into the test region between a pair of bearing members which are biased for relative motion and which are characterized by at least one porous bearing surface. The low viscosity component is absorbed by the porous bearing surface. The high viscosity component remains in the test region to establish characteristics which are indicated by the relative motion between the bearing members. The rheological properties of the high viscosity component are a function of these characteristics.
TL;DR: In this paper, the authors give interferometric measurements of oil films showing that, except near the upper edge of the film, the theory is accurately followed, and an optical technique suitable for practical implementation of the method is suggested.
Abstract: Oil is placed on a flat vertical surface and flows down under gravity. Theory shows that the oil should take up a parabolic profile, the square of the thickness being directly proportional to the viscosity and inversely proportional to the time from the start of flow. This suggests a method of viscosity measurement which has a number of potential advantages. The paper gives interferometric measurements of oil films showing that, except near the upper edge of the film, the theory is accurately followed. Comparisons with a U-tube viscometer show discrepancies, probably arising from lack of temperature control and other inadequacies in the apparatus. An optical technique suitable for practical implementation of the method is suggested.
TL;DR: In this article, the interpretation of interfacial shear flow data in the viscous traction surface viscometer in terms of aging effects on surface viscosity was examined and it was found that the surface shear viscoverage increased considerably with aging of dilute aqueous surfactant solutions.
TL;DR: In this article, an improved technique has been developed for studies of the shear viscosity of fluids, which utilizes an acoustic resonator as a four-terminal electrical device; the resonator's amplitude response may be determined directly and simply related to the fluid's viscosity.
Abstract: An improved technique has been developed for studies of the shear viscosity of fluids. It utilizes an acoustic resonator as a four-terminal electrical device; the resonator's amplitude response may be determined directly and simply related to the fluid's viscosity. The use of this technique is discussed briefly and data obtained in several fluids is presented.
TL;DR: In this article, the effect of gel-like material on measured second virial coefficients is discussed and it is suggested that the discrepancy in b arises because the larger aggregates remain in more mildly nitrated samples even after the larger aggregate has been removed by fractional precipitation.
TL;DR: In this paper, a Torsional Balance rheometer is used to measure shear and normal stress functions of greases. But the torsional flow between parallel plates is not held constant and the plate separation is allowed to adjust until the normal force is balanced by the axial load.
Abstract: A new instrument, a Torsional Balance rheometer, has been used to measure shear and normal stress functions of lubricating greases. The new rheometer is based on torsional flow between parallel plates, but differs from conventional torsional flow instruments in that the plate separation is not held constant but allowed to adjust until the normal force is balanced by the axial load. In dealing with materials that have a yield stress, such as greases, the Torsional Balance rheometer is superior to fixed-plate rheometers since the zero of the normal force measurement is not dependent on the yield stress. Results have been compared with those obtained on a capillary viscometer and a Weissenberg rheometer.
TL;DR: An automatic viscometer and sampling system suitable for monitoring changes in the molecular weight of polymers in solution is described in this article, which can be used to follow degradation or polymerization reactions induced by radiation, heat, or chemical reaction.
Abstract: An automatic viscometer and sampling system suitable for monitoring changes in the molecular weight of polymers in solution is described. Automation provides significant increases in precision and accuracy. The instrument can be used to follow degradation or polymerization reactions induced by radiation, heat, or chemical reaction. Examples are given of its application to the study of photolytic and chemical degradation of polymers.
TL;DR: Experimental results were presented which show a time dependent viscosity following a pressure step for three fluids at a given instant of time all three fluids appeared to reach a limiting viscosities, which became independent of pressure as discussed by the authors.
Abstract: Experimental results are presented which show a time dependent viscosity following a pressure step for three fluids At a given instant of time all three fluids appeared to reach a limiting viscosity, which became independent of pressure Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Montreal, Canada, October 8–10, 1974
TL;DR: In this paper, a viscometer, the inside of which was thoroughly coated by silicon grease, was prepared because it is difficult to measure precisely the viscosities of aqueous solutions of tetraphenylonium salts by means of a usual flow-type viscometers because of the characteristic peculiar to these solutions, that they make the glass wall water-repellent and water droplets tend to adhere to it.
Abstract: A viscometer, the inside of which was thoroughly coated by silicon grease, was prepared because it is difficult to measure precisely the viscosities of aqueous solutions of tetraphenylonium salts by means of a usual flow-type viscometer because of the characteristic peculiar to these solutions, that they make the glass wall water-repellent and water droplets tend to adhere to it. By comparing the relative viscosities on sucrose and LaCl3 in water obtained by the coated viscometer with those found in the literature, it was confirmed that the viscometer operates adequately. The viscosities of Ph4PCl, Ph4PBr, Ph4PNO3, Ph4AsCl, and Ph4AsBr in water have been measured at 15, 25, and 35 °C. The ionic B-coefficients determined at 25 °C are 1.09 mol−1 for both cations, while the ionic activation energies for viscous flow are +4.98 and +5.02 kJ/mol for Ph4P+ and Ph4As+ respectively.
01 Dec 1976
TL;DR: In this paper, a detailed study of viscous behavior of aqueous hydroxyethyl cellulose solutions has been made in a cone-and-plate viscometer over very wide ranges of shear rate and temperature.
Abstract: A systematic and detailed study of the viscous behavior of aqueous hydroxyethyl cellulose solutions has been made in a cone‐and‐plate viscometer over very wide ranges of shear rate and temperature. High shear stability and high degrees of pseudoplasticity have been observed. The rheograms have followed the Ostwald‐de Waele model. Simple and accurate expressions have been formulated relating temperature, solution‐concentration and power law exponent to consistency coefficient; also the solution‐concentration to activation energy.
TL;DR: In this paper, the viscosities of some aliphatic acids were measured in the vicinity of the melting point with a Hoppler viscosimeter, which is compared to that obtained from structural data.
Abstract: The viscosities of some aliphatic acids were measured in the vicinity of the melting point with a Hoppler viscosimeter. The dependence of the viscosity on the molar volume permitted calculation of the covolume, which is compared to that obtained from structural data.
TL;DR: In this article, a viscometer for use with a slurry or suspension was made using a special spindle in a Brookfield viscometers and the sample holder was designed such that the particles were maintained in uniform suspension by vigorous agitation.
Abstract: A viscometer for use with a slurry or suspension was made using a special spindle in a Brookfield viscometer. The design of the sample holder is such that the particles are maintained in uniform suspension by vigorous agitation, but the fluid motion does not affect the viscometer reading. The reading can be converted to absolute units by means of conversion factors derived from the geometry of the spindle and sample holder.
Patent•
23 Aug 1976
TL;DR: An electromechanical oscillator having a feedback shifted alternately to two different phases, and two digital function generators to derive viscosity and density signals on a time shared basis was used in this paper.
Abstract: An electromechanical oscillator having a feedback shifted alternately to two different phases, and two digital function generators to derive viscosity and density signals on a time shared basis.
Patent•
15 Dec 1976
TL;DR: In this paper, a viscometer for use in making viscosity measurements under operating conditions is presented, which includes a large turbine and a small turbine both operated by the in-line fluid flow.
Abstract: A viscometer for use in making viscosity measurements under operating conditions. The viscometer includes a large turbine and a small turbine both operated by the in-line fluid flow. By operating the two turbines simultaneously a comparison of their output frequencies can be made to indicate the ratio point and the viscosity of the fluid flowing is determined from the ratio point.
TL;DR: In this article, a Wells-Brookfield rotation viscosimeter was used to determine the viscosities of cell suspensions of human skin epithelium (NCTC strain 2544) and a viscosity of 1.094 centipoise (25° C, shear-rate 230 s−1) was found.
Abstract: Viscosities of cell suspensions of human skin epithelium (NCTC strain 2544) were determined by a Wells-Brookfield rotation viscosimeter. A structure viscosity may be postulated by the form of the viscosity curves at different shearrates. At a cell number of 0.5 × 106 cells/ml a viscosity of 1.094 centipoise (25° C, shear-rate 230 s−1) could be found. Since a suspension of single cells may be easily formed mechanically (mopping) the NCTC 2544 cells are useful as investigational model regarding the investigation of membrane characteristics.
TL;DR: In this paper, the intrinsic viscosity on gel permeation chromatography effluent was measured with use of an automatic viscometer in order to determine molecular characteristics of branched polymers.
Abstract: Direct measurement of intrinsic viscosity on gel permeation chromatography effluent was performed with use of an automatic viscometer in order to determine molecular characteristics of branched polymers. In analyzing the viscosity data, the instrumental spreading was considered. Results obtained from three low-density and one high-density polyethylene were compared with those obtained by such other methods as osmometer, light scattering, and column elution fractionation.
01 Jan 1976
TL;DR: In this paper, a simple, easy-to-use test for evaluating the suspension ability of a fluid, gives a ranking of some polymer fluids by their suspension ability, and relates this ability to a low shear-rate viscosity measurement of the fluid.
Abstract: The ability of a fluid to suspend particles is essential to the successful performance of fluids used in drilling, workover, and completion operations. The evaluation of a fluids-suspension ability has been by a comparison of the fluids' API yield point or by some apparent viscosity (i.e., funnel viscosity or viscometer apparent viscosity). This study presents a simple, easy-to-use test for evaluating the suspension ability of a fluid, gives a ranking of some polymer fluids by their suspension ability, and relates this ability to a low-shear-rate viscosity measurement of the fluid.
01 Jan 1976
TL;DR: In this paper, the surface stress-deformation behaviors of three liquid-air interfaces are calculated from measured velocity distributions in these interfaces, and an analysis suggested by Hegde and Slattery (27) is used to calculate the apparent surface shear viscosity of the phase interface as a function of the surface rate of deformation.
Abstract: I. ABSTRACT
The surface stress-deformation behaviors of three liquid-air interfaces are calculated from measured velocity distributions in these interfaces. The liquids studied are distilled water, a 6% aqueous solution of potassium oleate, and a n-octadecanol monolayer (20.5 a2/molecule) over distilled water.
For the interface between air and distilled water, the surface stress is independent of the surface rate of deformation; the surface viscosity is zero.
For the interface between air and a 6% aqueous potassium oleate solution, the surface stress is a linear function of the surface rate of deformation; the surface viscosity is 1.74 × 10−4 dyne sec/cm.
For the interface between air and a n-octadecanol monolayer (20.5 a2/molecule) over distilled water, the measured velocity distribution is not described well by assuming that the surface stress is a linear function of the surface rate of deformation. Instead, an analysis suggested by Hegde and Slattery (27) is used to calculate the apparent surface shear viscosity of the phase interface as a function of the surface rate of deformation. The apparent surface shear viscosity decreases as a function of the absolute value of the surface rate of deformation in a manner analogous to that observed with bulk stress-deformation behavior.
TL;DR: In this paper, a simple, inexpensive glass viscometer can be constructed to time the rate at which a rod falls into a liquid held in a concentric closed-end glass cylinder, which can be used to measure absolute values of apparent viscosities of Newtonian and non-Newtonian fluids.
Abstract: A simple, inexpensive glass viscometer can be constructed to time the rate at which a rod falls into a liquid held in a concentric closed-end glass cylinder. This equipment can be used to measure absolute values of apparent viscosities of Newtonian and non-Newtonian fluids. Calibration is not required. The technique is an adaptation of a method used previously with polymer melts at elevated temperatures. The present article describes the modifications needed for lower-viscosity fluids, such as paints, and validates the flow analysis with results of study of a characterized Newtonian fluid.