Capillary Methods

As a rule, in practice, the surface defects are revealed by the magnetic-powder and capillary methods. However, in the case of nonmagnetic materials the magnetic-powder methods are not applicable and the capillary ones do not detect the subsurface defects or defects filled with the lubricant after the grinding, wire-drawing and so on. 

Although not widely used, there are other methods to determine the softening point, such as the capillary method, the flow point, the drop point, and the Kofier method. The different methods provide different values of the softening point. In general, the Ring and Ball method provides the highest softening point while the... 

All three methods discussed above appear to provide equally high quality ionic liquid viscosity data. However, the rotational viscometer could potentially provide additional information concerning the Newtonian behavior of the ionic liquids. The capillary method has been by far the most commonly used to generate the ionic liquid viscosity data found in the literature. This is probably due to its low cost and relative ease of use. 

Of the electrical methods, only two representative methods will be considered here. Other electrical methods have been discussed previously, e.g., in Refs. 11 and 96. Capillary methods have been used often and discussed for their sources of errors and are therefore not particularly considered here. 

In the capillary method, the time required for a liquid to flow through a capillary tube is determined. The melt under investigation flows with a constant rate through a tube with a small, definite cross-sectional area, such as a cylindrical capillary. The viscosity can be measured in an absolute way from the pressure drop. This method can yield the most reliable absolute data, the viscosity being given by a modified Hagen-Poiseuille equation ... 

Comparison of in-line consistency measurement of tomato concentrates using ultrasonics and capillary methods),/. Food Proc. Eng. 25, 571. 

Apruzesse, W.A. and Vouros, P, Analysis of DNA adducts by capillary methods coupled to mass spectrometry a perspective, /. Chromatogr. A, 794, 97, 1998. 

Capillary methods are useful to determine diffusion coefficients. The method depends on the formation of a sharp boundary between the diffusing species in... 

Farng and Nelson [1] applied the capillary method to the determination of the diffusion coefficient of salicylic acid in the presence of polyelectrolytes. The reported variability in terms of the coefficient of variation ranged from 0.89% to 8.3%. Stout et al. [2] showed the tube method to be useful for determining diffusion coefficients of water-insoluble pharmaceuticals such as sulfonamides and steroids. The coefficient of variation associated with the diffusion coefficient for sulfisoxazole is 5.5%. 

The ability of any experimental method to produce accurate and reproducible results and provide the sensitivity needed to discern differences between transport mechanisms depends on minimizing variability intrinsic to the method. However, formal error analysis is rarely undertaken, even for commonly used methods. Fawcett and Caton [45] performed an error analysis of the capillary method for determining diffusion coefficients more than 25 years after the method was introduced. The value of the analysis is that it reveals which factors contribute the greatest variability to the dependent variable of interest. In the case of transport studies, the dependent variable of primary interest is diffusant concentration, C(t), where... 

N Fawcett, R Caton. Analysis of errors in the capillary method for determining diffusion coefficients. Anal Chem 48 228, 1976. 

Mobilities very sensitive to supporting medium and precision poor for quantitative work by traditional methods (5-20%) 0.5-3% for capillary methods. 

The infrared spectrum of valproic acid is presented in Figure 2. The spectrum was measured using the capillary method. The following bands (cm l) have been assigned for Figure 2 (1). 

P/ACE System MDQ chiral methods development P/ACE System MDQ highly sulfated cyclodextrin trial kit eCAP Amine Capillary Method Development Kit/Small Molecules eCAP Carbohydrate Labeling Kit... 

The capillaries (Itmn ID and 150 mm length tubular reactors) are heated rapidly (within 5 s) in a fluidized sand bed to the desired reaction temperature. Experimentation with the batch capillary method has revealed that, especially at low temperatures and high feed concentrations, char formation occms. A fluidized-bed reactor might be a good alternative to solve the problems related to this char and ash formation (Kruse et al., 2000). 

The diffusion coefficient of TcO " ascertained conductometrically has been found to be 1.48 X 10 cm xs whereas the self-diffusion coefficient measured with the capillary method in the presence of the supporting electrolytes 1 M... 

A more sensitive viscometer than the drop-time glass capillary method is also needed in size exclusion chromatography (SEC) such as the gel permeation chromatographic (GPC) analysis of polymer molecular weight distribution (MWD). In an SEC system, a concentration detector is commonly used for providing the weight concentration profile of the polymer elution curve. 

The values of melting points were determined by a modified capillary method. As can be seen from Figure 9.8-7 the pressure influences the melting point of glycerides. The reduction... 

The capillary method is simple to operate and precise (c. 0.01-0.1 per cent) in its results, but suffers from the disadvantage that the rate of shear varies from zero at the centre of the capillary to a maximum (which decreases throughout the determination) at the wall. Thus, with asymmetric particles a viscosity determination in an Ostwald viscometer could cover various states of orientation and the measured viscosity, although reproducible, would have little theoretical significance. 

DNLM 1. Nanotechnology—methods. 2. Electrophoresis, Capillary—methods. 

In all cases it should be appreciated that, when solutions rather than pure liquids are involved, there can be appreciable changes taking place with time at the surfaces and interfaces. Many of the methods which involve making new surfaces or interfaces are difficult or impossible to apply accurately to solutions. Also, where interfacial tensions are desired the second liquid competes with the first for attachment to whatever solid support is involved in the measurement method. This can cause hysteresis, and metastable menisci can result (eg., in du Noiiy, Wilhelmy and capillary methods). 

Williams, Ellard and Dawson92 have used the capillary method with 14C-labelled NMA to determine the self-diffusion coefficient of NMA. Values were found to range from 4.11 x 10-1° m2 sec-1 at 35 °C to 7.33 x 10-10 m2 sec-1 at 60 °C. The activation energy for the self-diffusion of NMA was calculated to be 19 kJ mol-1. This is quite close to the value of 19.2 kJ mol-1 calculated for the activation energy of viscous flow, thus suggesting the same rate controlling step for the two processes. 

The behavior of melt viscosity of sulfur-dicyclopentadiene solutions is of obvious interest from the point of sprayable coatings. The melt viscosity behavior has been reported recently, but only qualitatively and over a narrow range of compositions (18). The viscosity of sulfur measured by the capillary method by Bacon and Fanelli (19, 20) is considered to be the best (21). Recently, however, the viscosity of sulfur has been measured by an apparatus containing an electric motor and a rotating cylinder (22). Viscosity of the sulfur-DCP solutions are measured here with the help of a Brookfield synchro-lectric viscometer, which is of the later kind. Viscosity measurements have been carried out to follow the copolymerization reaction and to analyze the viscosity behavior. 

Selecki and Wasiak [54] have developed a modification of this technique which they named capillary method. Under the influence of a reduced pressure the foam moves continuously through a capillary tube with a known internal radius rin. The foam in the capillary is transformed into bubbles with extended cylindrical shape. By a lamp and two phototransistors the rate of film movement vy is measured, thus enabling to determine the equivalent diameter of each bubble... 

Caslavska J, Lienhard S, Thormann W (1993) Comparative use of three electrokinetic capillary methods for the determination of drugs in body fluids. J Chromatogr 638 335-342. 

The temperature effect on the polymerization of p-PDA Et is described in the range from —50 to 15 °C in Figs. 4 and 5. p-PDA Et, with a melting point of 100 °C (96 °C by the capillary method) and a crystal transition point of 56 °C (DSC), photopolymerizes quantitatively to a crystalline high polymer at a temperature below ca. 0°C as is obvious in Figs. 4 and 5. However, above ca. 25 °C, a partially cross-linked amorphous polymer is obtained in poor yield. 

---