Degree of Mixing Analyses of Concentrated Suspensions by Electron Probe and X-Ray Diffraction

Abstract

Two x-ray based techniques involving energy-dispersive analysis and diffractometry were introduced to the analyses of the degree of mixedness, i.e. the “goodness of mixing” of concentrated suspensions. A hydroxyl terminated polybutadene matrix was mixed with aluminum and ammonium sulfate. In the analysis, the ratio of the relative volume fractions of the two solid components was used as the basis of the analytical evaluation. Both characterization techniques are capable of determining the relative volume fraction of the two solid components as a representative measurement of the distributive mixing efficiency and both are sensitive to the scale of examination. The introduced techniques should be useful in the better definition of the degree of mixedness as well as in resolving differences in mixing efficiencies of various mixers used in processing of concentrated suspensions.

Twin-Screw Extrusion of Nano-Alumina–Based Simulants of Energetic Formulations Involving Gel-Based Binders

“…For a two-phase material (with absorption coefficients l 1 and l 2 for the individual phases), the absorption coefficient for the mixture becomes [1,2,[8][9][10]:…”

“…For example, the mixing indices show an increase with a decrease in the amount of the minor phase [12]. Sample size [8,12] and the number of samples analyzed also affect the values of the mixing indices.…”

“…These concentration values approach the overall concentration of the component in the mixture, /, as the sample size or the scale of the examination is increased. On the other hand, as the scale of the examination is reduced, the concentrations of the ingredients would deviate significantly from their mean values and in the limit the variance of the concentrations measured would reach the variance of a segregated sample [8].…”

“…The difference between the mean concentration, c c and the known overall concentration, /, of an ingredient (minor or the major component) is indicative of the quality of the Twin-Screw Extrusion of Nanoparticles sampling technique [1,2,[8][9][10]. This difference between c c and / diminishes as the number, N, of the characterized samples increases.…”

“…This difference between c c and / diminishes as the number, N, of the characterized samples increases. The measured concentration values of a component of the mixture depend also on the sample size [8][9][10][11][12][13]. These concentration values approach the overall concentration of the component in the mixture, /, as the sample size or the scale of the examination is increased.…”