Viscosity capillary viscometry

Shrinking of the polymer chains as a function of temperature was observed by capillary viscometry. The reduced viscosity, r]Sp/c, of polymer solutions approaches zero when the polymers are in their fully collapsed compact state and flow freely through the capillary. Above the cloud point, rjSp/c increases, which is indicative of aggregate formation. At low temperatures the... 

In addition, data on the size, shape and solvation of the polymer particles in aqueous solutions at temperatures below and above the transition phenomena registered by HS-DSC have been obtained [42]. Table 2 shows the results of capillary viscometry and light scattering experiments for the fractions p and s of poly(NVCl-co-NVIAz) synthesized at 65 °C from the feed with the initial molar comonomer ratio equal to 85 15. Since fraction p precipitates from the aqueous solution at temperatures > 34 °C, its intrinsic viscosity can be determined only at 20 °C, whereas for the fraction s such measurements were possible above and below the temperatures of the HS-DSC-registered conformational transition. 

In capillary viscometry, the fluid being measured flows through a capillary tube. How is this helpful in measuring viscosity ... 

Capillary viscometry measures the time it takes for the test fluid to flow through a capillary tube. The viscosity is calculated from this time and the calibration constant of the tube. 

HI. 3 Viscosity Determination of Pure Liquids, Solutions and Serums Using Capillary Viscometry... 

Basic Protocol Using Capillary Viscometry to Determine the Viscosity of Pure... 

BASIC USING CAPILLARY VISCOMETRY TO DETERMINE THE VISCOSITY OF PROTOCOL PURE LIQUIDS AND SOLUTIONS... 

This protocol describes a method for measuring the viscosity of pure liquids and solutions by capillary viscometry. The sample is loaded into a Cannon-Fenske viscometer. The time required for the sample to flow between two time points on the viscometer is used to calculate the kinematic viscosity or viscosity. 

Viscosity Measurements, Previous studies (2) have shown that dilute solutions of Pluronic F127 exhibit Newtonian flow characteristics and consequently, it is permissible that the viscosity of these solutions is measured by capillary viscometry. A suspended-level viscometer was used and solutions were thermostatted to within... 

Capillary viscometry was the first method used to measure the viscosity of fluids. This procedure, based on the relationship between pressure drop and flow rate, was independently developed by Hagen and Poiseuille (see Ref. 29). It is one of the most widely used techniques for studying the flow behavior of fluids. 

Shrinking of the polymer chains as a function of temperature was observed by capillary viscometry. The reduced viscosity, of polymer solu-... 

The methodology of capillary viscometry of liquids rests on the laws of flow through a fine-bore tube. The viscosity is determined from the measured flow rate under a known applied pressure through a tube of known dimensions. 

Figure 4-12 shows the data obtained by rotational and by capillary viscometry for the non-Newtonian flow of a liquid lubricating oil containing a polymeric viscosity modifier [11]. There is no systematic dependence of viscosity on the type of viscometer used, but the decrease of viscosity with increasing rate of shear is unmistakably evident. 

PoiseuilWs Law Poiseuille flow is the steady flow of incompressible fluid parallel to the axis of a circular pipe or capillary. Poiseuille s law is an expression for the flow rate of a liquid in such tubes. It forms the basis for the measurement of viscosities by capillary viscometry. 

Capillary Viscometry. The viscosity of dilute solutions of the polymer was determined with a Canon-Fenske capillary viscometer set in a thermostat bath at 25 0.05 C. A stock solution of 0.15 g dL was prepared in distilled water, stored at 4 C for 2 days, and then filtered through a No. 1 sinter glass funnel to remove fibers and detritus from the preparation of the cellulose ether. Nine other solutions were prepared from this stock by dilution with filtered distilled water. All these solutions were then stored at 4 C for a further 24 h to ensure that all the solutions had the same temperature history, as this factor has been shown to be important in producing reproducible solutions of cellulose ethers (4, 5). The concentration range prepared was 0.015-0.15 g dL" and the flow times ranged from 294 to 1609 s. 

Capillary Viscometry. The viscosity data are plotted in Figure 1 as the reduced viscosity r re as a function of concentration. The curve shows two linear plots that intersect at a polymer concentration, c, of0.075 g dL If the Huggins equation (5)... 

Measurement of the Intrinsic Viscosity The principle behind capillary viscometry is the Poiseuille s law, which states that the time of flow of a polymer solution (ps) through a thin capillary is proportional to the viscosity of the solution. The latter increases with increasing solution concentration. From Equation 17.6, the time of flow of the solvent (solv) or of the polymer solution will be proportional to the viscosity, and inversely proportional to the density ... 

It is possible to add a second, molecular weight-sensitive detector to an SEC system to provide a direct means of absolute molecular weight calibration without the need to resort to external standards. These detectors represent refinements in classic techniques, such as light-scattering photometry, capillary viscometry (for intrinsic viscosity), and membrane osmometry for on-line molecular weight determination. Yau recently published a review of this subject with comparisons of the properties and benefits of the principal detectors currently in use (22). The present discussion is restricted to lightscattering and viscometry detectors because Yau s osmometry detector is not yet commercially available. The reader is referred to Chapter 4 for a comprehensive discussion of molecular weight-sensitive detectors. 

Capillary viscometry is used for the determination of relative viscosity of polymer solutions in an appropriate solvent at diluted concentrations. Relative viscosity is dependent on concentration, so the concentration is specified for the solution. Relative viscosity is also dependent on the viscometer used therefore, the size of the tube used for the measurement... 

Chief among the absolute methods is capillary viscometry, where the viscosity is calculable from Poiseuille s relation ... 

Figure 14.10 shows capillary viscometry data at 150°C for the lUPAC A LDPE considered earlier in Figure 14.7. It is apparent that these data blend nicely with the data generated using a cone-and-plate viscometer. At shear rates greater than about 1 sec , the viscosity-versus-shear rate behavior is linear. Consequently, one can say that the shear stress x (where subscripts have been dropped for convenience) is given by...

For Molecular weight determination by viscometry we do not need absolute h value, viscosity measurements may be carried out in simple Ostwald Viscometer. Because of (the non-Newtonian behaviour of most macromolecular solutions at high velocity gradients in the capillary, the viscometer dimensions are chosen in such a manner that the viscosity gradient is the smallest possible. 

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