Viscometers Ubbelohde

Fig. 24. (a) Ostwald glass capillary viscometer, (b) Cannon-Fenske viscometer, and (c) Ubbelohde viscometer. 

The Ubbelohde viscometer is shown in Figure 24c. It is particularly useful for measurements at several different concentrations, as flow times are not a function of volume, and therefore dilutions can be made in the viscometer. Modifications include the Caimon-Ubbelohde, semimicro, and dilution viscometers. The Ubbelohde viscometer is also called a suspended-level viscometer because the Hquid emerging from the lower end of the capillary flows down only the walls of the reservoir directly below it. Therefore, the lower Hquid level always coincides with the lower end of the capillary, and the volume initially added to the instmment need not be precisely measured. This also eliminates the temperature correction for glass expansion necessary for Cannon-Fen ske viscometers. 

Viscosity average molecular weights Mv were determined using a Ubbelohde viscometer and diisobutylene solutions at 20 °C with at least three dilutions for every solution. The Mv was calculated from intrinsic viscosity28. Averages of two determinations are reported. Reproducibility was 10%. 

Relative viscosities were measured in 0.1 M phosphate buffer pH 6.0 using an Ubbelohde viscometer. 

Dilute Solution Viscometry - The hydrogenated and hydroformyl ated (10%) PBD were completely soluble in toluene. Intrinsic viscosity measurements were carried out in toluene at 30°C using a Cannon-Ubbelohde viscometer. 

Methodology Various fraction of crude oil was distilled under different condition after being sonicated by an ultrasonic processor for different intervals of time. Density of these fractions was determined by dialatometer. Viscosities of these fractions were measured using Ubbelohde viscometer and the results given as under ... 

Figure 5 shows three different types of capillary viscometers often used for viscosity measurements of polymer solutions. The disadvantage of the Oswald viscometer is that the viscometer has to be charged with the solution to a precise level and fine adjustments need to be made at the temperature of measurement. The Ubbelohde viscometer, also frequently referred to as the suspended level viscometer, is particularly useful when a series of different polymer concentrations is to be measured. The filling volume needs not to be adjusted precisely. The largest dilution ratio obtainable is limited only by the ratio of the volume of bulb B to that of the volume between the bottom of bulb B and the top of bulb C. For the compact version (Figure 5(c)) smaller sample volume is needed. There are also capillary viscometers available that can be coupled with liquid... 

Viscometric manipulations are simplified considerably by using the modified Ubbelohde viscometer described by Davis and Elliott.26,126 This type of capillary viscometer can be modified to enable an estimate of the shear correction to be made,127 although a Couette viscometer128 is more satisfactory for this purpose. 

Polymer solutions were prepared by dispersing the polymer powder in a saline solution prepared with distilled deionized water. Following complete dispersion in the vortex of the fluid the samples were agitated under mild conditions (< 100 RPM) until the solution was homogeneous. For some solutions the dissolution was so rapid that the agitation step could be eliminated. The polymer viscosities were then measured using a Ubbelohde viscometer. The pH of the polymer solutions was adjusted using dilute acetic acid and sodium hydroxide. Some polymers were supplied as liquids and were subsequently diluted with distilled deionized water to the appropriate concentration. 

The error in the determination of the efflux time because of the deflection of the viscometer from the vertical is much larger in Ostwald viscometer than in Ubbelohde viscometer. 

The Cannon-Fenske viscometer is used for measuring the kinematic viscosity of transparent Newtonian liquids, especially petroleum products and lubricants. The Ubbelohde viscometer is also used for the measurement of kinematic viscosity of transparent Newtonian liquids, but by the suspended level principle. 

Distinguish between a Cannon-Fenske viscometer and a Ubbelohde viscometer. 

Ubbelohde viscometer with efflux times greater than 100 sec for the solvent... 

Using a 10-ml volumetric pipette, deliver 10 ml of filtered toluene to bulb A of the Ubbelohde viscometer (Fig. 17.1) (see Note 3). 

Viscosity measurements were made with two Cannon-Ubbelohde viscometers, and timing was by an optical device actuating an electronic timer (Wescan Instruments, Inc.). An air thermostat was used. The viscometers were calibrated with redistilled air-saturated water over the range 10°-50°C. The kinetic-energy correction was used in the form ... 

Experimental. Viscosities. The absolute viscosities in centipoises (cp.) for several amide-water systems at 25 °C. were obtained using calibrated Ubbelohde viscometers and calculated from -q = p[Kt — L/t where p is density of mixture, and K and L are instrument constants. The results, plotted against the mole fraction of water, are shown in Figures 1 and 8. 

The intrinsic viscosities of poly(4-methyl-l-pentene) s in tetrahydrofuran at 27° C were determined using an Ubbelohde viscometer. 

Physical Measurements. Intrinsic Viscosities. Intrinsic viscosities were obtained using dilute solution viscometry (Cannon-Ubbelohde viscometers). 

Physical Measurements. Molecular Weight. Intrinsic viscosities were determined using dilute solution viscometry (Cannon-Ubbelohde viscometers). For the poly (methyl methacrylate) polymer the following empirical expressions were used to obtain molecular weights (4) ... 

Intrinsic viscosity serves as a measure ofthe hydrodynamic volume of a single particle in the solution under study. Viscosity of micellar solutions can be measured using an Ubbelohde viscometer at a given temperature (AstaLeva et al., 1993 Pandya et al., 1993 Zhou and Chu, 1994). The temperature ofthe thermostatted bath is usually controlled within 0(D2o obtain an accurate measurement. Aftera desired temperature is set, each solution should be temperature-equilibrated for at least 20 min before viscosity measurement. An average low time is taken for several consecutive measurements on the same copolymer solution to calculate the viscosity value. 

In 2003, we first used self-assembled zinc(II) terpyridine polymers in the fabrication of PLEDs.22 We synthesized a series of monomers containing two terpyridine as chelating units, which are at opposite ends and separated by a spacer group (R) (Fig. 5). The self-assembled zinc(II) coordination polymers were easily prepared by the addition of Zn(OAc)2 into solution of monomers. The product yields were up to 80%, and the inherent viscosities of the polymers were in the range of 0.48 to 1.21 dL/g, as determined using an Ubbelohde viscometer in NMP at 30 0.1 °C. 

Inherent viscosity measured in NMP at 30 0.1°C, using Ubbelohde viscometer. 

Intrinsic viscosities were measured in benzene at 30 °C. using a Cannon-Ubbelohde viscometer with flow time greater than 200 sec. Results are expressed in deciliters/gram and for poly (methyl methacrylate) (PMMA) were converted to molecular weights by the following equations (4, 12) ... 

Intrinsic viscosities of BBB in methanesulfonic acid were determined with a suspended level Ubbelohde viscometer by extrapolating the data for at least four concentrations to infinite dilution according to the simultaneous extrapolations ... 

Viscosities. The reduced solution viscosities (RSV) of the polymers (0.1 gram per 100 ml. of solution) were measured at 135° C. in decalin using modified Ubbelohde viscometers. 

Select a viscometer having a minimum flow time of at least 200 s. Use a No. 3 size Ubbelohde, or a No. 400 size Cannon-Ubbelohde, viscometer for the range of 300 to 600 centistokes. The viscometer should be fitted with holders that satisfy the dimensional positions of the separate tubes as shown in the diagram and that hold the viscometer vertically. Filling lines in bulb A indicate the minimum and maximum volumes of liquid to be used for convenient operation. The volume of bulb B is approximately 5 mL. 

The Intrinsic viscosities obtained In the Cannon Ubbelohde viscometer were corrected for shear effects by using the curve shown In Figure 2. This curve was obtained by using a Zlmm-type low shear viscometer (17) to determine the Intrinsic viscosities of four emulsion polymerized polystyrene samples (. The curve was linear over the range of Intrinsic viscosity results for polystyrene samples encountered In this study. 

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