Pycnometric method

Densities determined by pycnometric methods may be compared with those determined by X-ray diffraction. The pycnometric density is dependent on the presence of vacancies or interstitials, being lower or higher, respectively [46]. 

The volume of single granules of shape close to spherical was calculated on the basis of their dimensions in three main directions, using the formula for ellipsoid. The volume of granules of shape different from spherical was determined by the pycnometric method. 

The weight of solids per unit-volume of suspension, W, entails no difficulty in its determination [Pg.344]

Evaluation of microporous structure of carbon molecular sieves using the pycnometric method... 

The total porosity of solids can be estimated by simple pycnometric methods using the differences in surface tension between gases and mercury. By definition, the porosity Pr(%) is given by ... 

For determination of the overall porosity, pycnometric methods are recommended that use imbibition of the material in a light inert gas and mercury. Mercury porosimetry is the method of choice for assessing macro- and meso-pores. The use of intrusion and extrusion measurements is necessary to understand more complex pore structures. 

Traditionally, density of hydrated portland cement was measured in the d-dried state by pycnometric methods, using a saturated solution of calcium hydroxide as a fluid. Since the d-dried hydrated portland cement rehydrates on exposure to water, this method is of questionable value. More realistic values can be obtained by proper conditioning of the sample and using fluids that do not affect the structure of the paste. 

Y. Sato, T. Nishizuka, K. Hara, T. Yamamura, and Y. Waseda, 2000, Density measurement of molten silicon by a pycnometric method ... 

The volume of the solid phase Vp is usually measured by a pycnometric technique, which measures the excluded volume of a pycnometric fluid, whose molecules cannot penetrate the solid phase of PS. A simple example of a pycnometric fluid is helium [55], The pycnometric fluid fill in all void space (pores) accessible to it, and presumably do not adsorb on the surface of PS. In the case of microporous PSs, measurement of the volume accessible for guests with various sizes allows the determination of a distribution of micropores volume vs. the characteristic size of guest molecules. This approach lays the basis of the method of molecular probes. The essence of this method is in the following we have a series of probe molecules with different mean sizes (dl>d2>d3>---). The pycnometric measurements of the excluded volume will give a series The difference A V=Vpi-Vpi(i>j) corresponds to the volume of micropores with pycnometric sizes of d in a range dt[Pg.283]

The pycnometric procedure for determining ethanol is still the reference method for many countries although few laboratories use it routinely. In cases involving commercial transactions it is preferred, especially since the calculations can be simplified. 

For description of textural properties of carbonaceous adsorbents, adsorption/desorption isotherms of vapours and gases in static conditions as well as mercury porosimetry are used. The latter method often leads to destruction of porous structure of investigated materials while the usage of the former one is affected by the specific properties of molecular sieves described above. Taking into account these limitations, in this work the authors have made an attempt of determination of porous structure of carbon molecular sieves with the used of the pycnometric technique. 

Density of the Dry Cell Wall. The dry cell wall of wood has a density of approximately 1.5 g/cm when measured by pycnometric or volume-displacement methods. Somewhat higher values are obtained when using water as opposed to nonswelling displacement media such as toluene or benzene (22). 

The two methods, most commonly used to measure gravimetric density, are pycnometric and flotation. In a pycnometric technique, the volume of the material is determined from the volume of a fluid displaced by the known mass of a material. In a flotation approach, a small particle, whieh can be a single crystal, is placed in a low-density fluid, where it... 

Scandium oxide single crystals can be synthesized in only H2 atmosphere by the Vemeuil method [107]. The linear growth rate was about 8 mm h and the size of the obtained crystal has 45 mm length and 4 mm diameter. Pycnometric density of the obtained SC2O3 single crystal was 3.91 g-cm", Mohse hardness was 6.5, and refractive index was 1.91. 

An additional factor which may have an impact on the vacuum properties is the closed cell content of the PU foam. All the open cell PU foams so far presented in the literature for VIP applications are quoted to be 100% open cell based on pycnometric measurement. On the other hand, the accuracy of this test method is generally close to 0.2% [15], so that the possibility of a small fraction of closed cells cannot be completely ruled out and has to be considered as an additional potential source of pressure build-up in the panel. 

Methods—Chemical. Fabre and Br5mond (1935) compared pycnometric, hydrometric, ebulliometric, and chemical methods for determination of alcohol and for the most accurate results preferred the chemical over the pycnometric. The former is based on oxidation of the alcohol with dichromate. Prior to chemical determination of alcohol in sweet wines and vermouth, Paronetto (1938) used a double distillation, the second one with alkali. A special adaptation of the chemical method for the determination of alcohol was proposed by Schulek and Rdzsa (1939), in which the distilled alcohol was purified by adsorption on charcoal. 

Defects can be discovered and determined by different experimental methods. By measurement of the electrical conductivity (see to Mixed Conductors, Determination of Electronic and Ionic Conductivity (Transport Numbers)) in dependence on partial pressure and temperature [5, 6] and the heat capacity in dependence on temperature [7], the defect formation could be detected. Hund investigated the defect structure in doped zirconia by measurement of specific density by means of XRD and pycnometric determination [8]. Transference measurements [9] and diffusion experiments with tracers [10-12] or colored ions [4] are suited for verifying defects. 

After the purification by these methods, incombustible impurities and oxidized forms of carbon in the synthesized powders were assayed. For some samples, the pycnometric density was determined. The efficiency of the methods used to produce pure powders of ultradisperse diamonds was assessed based on these solid-phase parameters (Table 2.1). 

Although pycnometric measurements are simple and straightforward in principle, there are enough pitfalls in the method when applied to clay systems to explain the considerable deviations in the results of various investigations reported in the literature. Experimentally, the completely air-free loading of the pycnometer with sufficient amounts of a clay, particularly the gelling clays, to obtain accurate data is difficult. The determination of the dry weight of the clay in the pycnometer requires that the clay is vacuum dried and completely handled in a dry box. 

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