Washburn method

The wettability of the PE powders was evaluated in terms of contact angle using the Washburn method [7] with benzyl alcohol and ethylene glycol. Each contact angle value corresponds to the mean value of three measurements. The accuracy of the results is 3°. 

To improve the current models, the contact angles in the interior of PTL samples have been calculated via sorption experiments (Gurau et al., 2006 Gurau and Mann Jr., 2010 Parry et al., 2010) that were based on modified versions of the Washburn method (Washburn, 1921). 

Section 3.7, the gas adsorption method breaks down for practical reasons. Since the angle of contact of mercury with solids is 140° (see later), and therefore more than 90°, an excess pressure Ap is required to force liquid mercury into the pores of a soh d. The idea of using mercury intrusion to measure pore size appears to have been first suggested by Washburn who put forward the basic equation... 

Viscosity, defined as the resistance of a liquid to flow under an applied stress, is not only a property of bulk liquids but of interfacial systems as well. The viscosity of an insoluble monolayer in a fluid-like state may be measured quantitatively by the viscous traction method (Manheimer and Schechter, 1970), wave-damping (Langmuir and Schaefer, 1937), dynamic light scattering (Sauer et al, 1988) or surface canal viscometry (Harkins and Kirkwood, 1938 Washburn and Wakeham, 1938). Of these, the last is the most sensitive and experimentally feasible, and allows for the determination of Newtonian versus non-Newtonian shear flow. 

Reynolds LJ, Washburn WN, Deems RA, Dennis EA (1991) Methods Enzymol 197 3... 

Relation 9.77 is usually called the Washburn equation [55,237], One should consider it as a special case of the fundamental Young-Laplace equation [3,9-11], Washburn was the first to propose the use of mercury for measurements of porosity. Now, it is a common method [3,8,53-55] of psd measurements for a range of sizes from several hundreds of microns to 3 to 6 nm. The lower limit is determined by the maximum pressure, which is applied in a mercury porosimeter the limiting size of rWl = 3 nm is achieved under PHg = 4000 bar. The measurements are carried out after vacuum treatment of a sample and filling the gaps between pieces of solid with mercury. Further, the hydraulic system of a device performs the gradual increase of PHg, and the appropriate intmsion of mercury in pores of the decreasing size occurs. 

The experiments are usually carried out at atmospheric pressure and the initial goal is the determination of the enthalpy change associated with the calorimetric process under isothermal conditions, AT/icp, usually at the reference temperature of 298.15 K. This involves (1) the determination of the corresponding adiabatic temperature change, ATad, from the temperature-time curve just mentioned, by using one of the methods discussed in section 7.1 (2) the determination of the energy equivalent of the calorimeter in a separate experiment. The obtained AT/icp value in conjunction with tabulated data or auxiliary calorimetric results is then used to calculate the enthalpy of an hypothetical reaction with all reactants and products in their standard states, Ar77°, at the chosen reference temperature. This is the equivalent of the Washburn corrections in combustion calorimetry... 

It is of interest to point out that Washburn and Urey proposed a method for enriching deuterium based on the experience that, during electrolysis, the cathodic reaction with the lower cathodic potential will occur almost to the exclusion of other cathodic reactions. Reasoning that the reduction potentials of H+ and D+ may differ, they proposed electrolysis could be used to enrich deuterium. Pursuing that idea they found the residual water in a commercial water electrolysis apparatus used for... 

Gurau et al. [194] proposed a method to estimate the internal contact angle to water by combining the Washburn technique with the Owens-Wendt... 

A commonly used simple method for determining if there are any cracks or pinholes in microporous membranes is the so-caUed bubble point test. It has been used by many organic membrane manufacturers and users alike and is also being adopted by some inorganic membrane manufacturers. The method utilizes the Washburn equation... 

According to the Washburn equation (10.23) a capillary of sufficiently small radius will require more than one atmosphere of pressure differential in order for a nonwetting liquid to enter the capillary. In fact, a capillary with a radius of 18 A (18 x 10 ° m) would require nearly 60 000 pounds per square inch of pressure before mercury would enter-so great is the capillary depression. The method of mercury porosimetry requires evacuation of the sample and subsequent pressurization to force mercury into the pores. Since the pressure difference across the mercury interface is then the applied pressure, equation (10.23) reduces to... 

The development of a commercial mass spectrometer and its application to hydrocarbon gas analysis by the method of Washburn et al. (63) made gas analysis rapid, economical, and, what is even more important, inspired a confidence in the results of routine hydrocarbon gas analysis which was badly lacking. A complex gaseous mixture comprising the atmospheric gases, carbon monoxide, and Ci to C6 hydrocarbons required more than 20 hours of applied time by the previous methods of low temperature fractional distillation coupled with chemical absorption methods. With the mass spectrometer such an analysis is completed in 2 hours or less, about 15 minutes of which is consumed in the... 

Washburn, E.W. (1921) Note on a method of determining the distribution of pore sizes in a porous material. Proc. Natl. Acad. Sci. USA, 7, 115. 

LJ Reynolds, WN Washburn, RA Deems, EA Dennis. Assay strategies and methods for phospholipases. In EA Dennis, ed. Methods in Enzymology 197. Orlando FL Academic Press, 1991, pp 3-23. 

Mercury porosimetry is the most suitable method for the characterization of the pore size distribution of porous materials in the macropore range that can as well be applied in the mesopore range [147-155], To obtain the theoretical foundation of mercury porosimetry, Washburn [147] applied the Young-Laplace equation... 

Scaffold porosity and information on the pore size distribution can be obtained from intrusion techniques. The most commonly used methods are mercury porosimetry and capillary flow porometry. In mercury porosimetry the pressure required to fill a tissue scaffold with non-wetting mercury is monitored over a set period of time. Higher pressures are required to fill small pores than large pores a fact that can be exploited using the Washburn equation13 to extract structural information where D is the diameter of the pore at a particular differential... 

The applied pressure is related to the desired pore size via the Washburn Equation [1] which implies a cylindrical pore shape assumption. Mercury porosimetry is widely applied for catalyst characterization in both QC and research applications for several reasons including rapid reproducible analysis, a wide pore size range ( 2 nm to >100 / m, depending on the pressure range of the instrument), and the ability to obtain specific surface area and pore size distribution information from the same measurement. Accuracy of the method suffers from several factors including contact angle and surface tension uncertainty, pore shape effects, and sample compression. However, the largest discrepancy between a mercury porosimetry-derived pore size distribution (PSD) and the actual PSD usually... 

The porosity of solid samples can be quantitatively studied by mercury poro-simetry. The total volume, specific surface area of the pores, bulk density, and particle size can be determined in 1.8 nm-300 pm pore size and 15 nm-3 mm particle size. The principle of the method is that there is a relationship between the pressure of mercury and the size of the pores filled with mercury. The pressure of mercury (p) required for its introduction into the pores of a given radius (r) can be expressed by Washburn s equation ... 

This method is based on the fact that a liquid that does not wet a porous solid will enter its pores only under pressure. If the pores are assumed to be cylindrical, the pressure (p) needed to force the liquid into them is given by the Washburn equation... 

Two methods have been used to obtain Washburn numbers W2, wj or solvent transference numbers A. 

Horens L, Washburn MP. Proteomic analysis by multidimensional protein identification technology. Methods Mol. Biol. 2006 328 159-175. 

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