Andrade equation

It was just stated that the viscosity of liquids and dispersions usually decreases as temperature increases. An exception is the case of gases whose viscosities usually increase slightly with temperature, with a temperature coefficient of about 0.3% per degree Kelvin [383]. The viscosities of liquids usually decrease with increasing temperature, and more strongly. A number of equations, of varying degrees of complexity, have been formulated to enable one to empirically predict liquid viscosities as a function of temperature [384—386]. A simple, often used, relation is the Andrade equation,... 

The viscosity of a pure liquid can be determined as a function of the temperature when there are two or more values of viscosity for determining the constants A and B. The Guzman-Andrade equation (14), presents maximum errors of 2% ... 

The calculation of viscosities of electrolyte mixtures can be accomplished with the method of Andrade (see Ref. [40]) extended with the electrolyte correction by Jones-Dole [44]. First, the pure component viscosities of molecular species are determined by the three-parametric Andrade equation, which allows a mixing rule to be applied and the mixture viscosity of an electrolyte-free liquid phase to be obtained. The latter is transformed into the viscosity of the liquid phase using the electrolyte correction term of Jones and Dole [44], whereas the ionic mobility and conductivity are used as model parameters. 

Three points are noteworthy for the Kyukoshi method. (i) Rapid heating of the hydrogenated pitch to above 450°C produces a pitch suitable for smooth spinning. (ii) This pitch appears to be isotropic at the spinning temperature of 370°C. (iii) The viscosity-temperature relationship, plotted in Figure 8 in terms of the Andrade equation... 

It is well known in most cases that the speed of chromatographic separations can be increased by increasing the temperature due to enhancement of the transport properties, such as diffusivity and fluidity. The temperature dependence of viscosity of the mobile phase is usually described by the Andrade equation [50] as... 

Liquids Liquid viscosity can be correlated as a function of temperature for low pressures. Usually the correlation is based on the Andrade equation [Andrade, E. N. da C., Nature, 125 (1930) 309]... 

Results from the DIPPR project (5) were selected for viscosity of liquid. Data were correlated using the de Guzman - Andrade equation with extended terms ... 

The DIPPR project (5) was also selected for viscosity of liquid. Temperatures from below the boiling point to temperatures above the boiling point are covered for most of the compounds. Data for liquid viscosity as a function of temperature were correlated using the de Guzman - Andrade equation with extended terms, Equation (1-8). Correlation results and data are in favorable agreement with errors being about 1-5% or less. 

Our present focus is on the values of F (T) that are contained in the convoluted fits to equation (9) obtained in cis-decalin over the temperature range from 237 K to 429 K. These results give cage efficiencies for the photochemical case directly and predict those for the corresponding collisional case where K may be set equal to one. The viscosity of this solvent has been characterized (Table I) and fits the Andrade equation (6) with an of 3685 cal/mole and a pre-exponential constant (Aj ) of 6.45X10 cP. These results are summarized in Table I and Figure 2. 

Finally the effect of temperature on solvent viscosity can be calculated using the Andrade equation ... 

Cl and C2 are constants showing significant dependence on the composition of the pitch. Although the LDF equation gives a better fit, Otani and Oya [264] used the Andrade equation (rj = to plot rj Vs IjT for two different pitches and when two straight lines... 

Interestingly, the equation is the same as the Andrade equation for creep of metal. 

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