Powders and solids

Actinide metals with lower vapor pressures (Th, Pa, and U) cannot be obtained by this method since no reductant metal exists which has a sufficiently low vapor pressure and a sufficiently negative free energy of formation of its oxide. For the large-scale production of U, Np, and Pu metals, the calciothermic reduction of the actinide oxide (Section II,A) followed by electrorefining of the metal product is preferred (24). In this process the oxide powder and solid calcium metal are vigorously stirred in a CaCl2 flux which dissolves the by-product CaO. Stirring is necessary to keep the reactants in intimate contact. 

Nitroglycerine is a very powerful secondary explosive with a high brisance, i.e. shattering effect, and it is one of the most important and frequently-used components for gelatinous commercial explosives. Nitroglycerine also provides a source of high energy in propellant compositions, and in combination with nitrocellulose and stabilizers it is the principal component of explosive powders and solid rocket propellants. 

The most commonly measured pigment properties are elemental analysis, impurity content, crystal structure, particle size and shape, particle size distribution, density, and surface area. These parameters are measured so that pigments producers can better control production, and set up meaningful physical and chemical pigments specifications. Measurements of these properties are not specific only to pigments. The techniques applied are commonly used to characterize powders and solid materials and the measuring methods have been standardized in various industries. 

XRF offers a unique approach for rapid, non-destructive elemental analysis of liquids, powders, and solids. Although the first row transition elements are the most sensitive, elements from atomic number 12 (magnesium) and greater can be measured over a dynamic range from trace (ppm) to major (percent) element concentrations. EDXRF is well suited for qualitative elemental identification of unique samples, while WDXRF excels at high precision quantitative analysis. 

In devolatilization with viscous polymeric melts, it is difficult, of course, to carry out similar experiments and prove indirectly that free-streaming nuclei may play a similar role, but microscopic particles originating from the monomers and catalyst systems are likely to be found in the polymeric product. Moreover, it is well known that the addition of fine powders and solid particles induces foaming. Therefore, the Biesenberger-Lee proposition seems plausible. 

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