Composite multi-component

Random, graft, and alternating copolymerization Monomer polymer composition—copolymers Monomer polymer composition—terpolymers Monomer polymer composition—multi-component terpolymers Free radical concentration Reactivity ratios... 

Constant overhead composition, vaiying reflux. If it is desired to maintain a constant overhead composition in the case of a binaiy, the amount of reflux returned to the column must be constantly increased throughout the run. As time proceeds, the pot is gradually depleted of the hghter component. Finally, a point is reached at which the reflux ratio has attained a veiy high value. The receivers are then changed, the reflux is reduced, and an intermediate cut is taken as before. This technique can also be extended to a multi-component mixture. 

The X-ray microanalysis is the basic method of study of rare-metal and rare-earth minerals of micron size. The multi-component composition, instability of minerals under the electron beam, overlap of X-ray characteristic lines, absence of reference samples of adequate composition present difficulties in the research of mineral composition. 

The relationship between what is recorded in a SSIMS spectrum and the chemical state of the surface is not as straightforward as in XPS and AES (Chap. 2). Because of the large number of molecular ions that occur in any SSIMS spectrum from a multi-component surface (e. g. during the study of a surface reaction), much chemical information is obviously available in SSIMS, potentially more than in XPS. The problem in using the information from a molecular ion lies in the uncertainty of knowing whether or not the molecule represents the surface composition. For some materials. 

Multilayer coatings of different composition and thickness are widely used in materials science and in the production of high-technology materials. The single- or multi-component thin layers significantly improve important characteristics of the materials with, e.g., specific properties. 

CHEMCALC 1, Separations Calculations Gulf Publishing Company, Book Division P.O. Box 2608 Houston, TX 77252 Programs for use with multi-component mixtures to determine the conditions and compositions at the dew point and at the bubble point. 

Equilibrium data are thus necessary to estimate compositions of both extract and raffinate when the time of extraction is sufficiently long. Phase equilibria have been studied for many ternary systems and the data can be found in the open literature. However, the position of the envelope can be strongly affected by other components of the feed. Furthermore, the envelope line and the tie lines are a function of temperature. Therefore, they should be determined experimentally. The other shapes of the equilibrium line can be found in literature. Equilibria in multi-component mixtures cannot be presented in planar graphs. To deal with such systems lumping of consolutes has been done to describe the system as pseudo-ternary. This can, however, lead to considerable errors in the estimation of the composition of the phases. A more rigorous thermodynamic approach is needed to regress the experimental data on equilibria in these systems. 

Standard thin films of known composition may not always be available, and in multi-component systems many k factors should be determined, which is a time-consuming process. A new quantitative procedure for thin specimens has been developed to overcome these limitations ... 

Therefore, Ca, Cb and pt can be determined simultaneously by measuring X-ray intensities (if the specimen density and thickness are known). Only f factors are required and k factors are not used. This approach can be extended to any multi-component system if one assumes J]Ci=l. The factors are measured from standard thin films with known composition and thickness, the advantage being that pure element thin films can be applied as standards. 

It is very difficult to cool pure metals and other pure elements fast enough to form glasses. However, metallic alloys can often be converted into glasses, particularly if they contain a mixture of small and large atoms such as iron and boron, or they are multi-component mixtures of metals that crystallize into more than one intermetallic compound (i.e., eutectic compositions). Thus, covalent chemical interactions of the atoms are important because they stabilize liquids and thereby inhibit crystallization. 

In multi-component liquids, stabilization of the liquid is revealed by the formation of eutectics where the freezing temperature is suppressed. In such liquids, the atomic species (say A and B) are not distributed at random. There are more associated AB pairs (or other clusters) than expected for a random distribution. As a result in binary metal-metalloid alloys, such as Fe-B, the low melting-point eutectics occur at preferential compositions. The most common of these is at about 17 at. % B, or an atom ratio of one B for five Fe atoms (Gilman, 1978). This suggests that clusters of metal atoms surrounding metalloid atoms form (trigonal bipyramids). These probably share corners, edges, and faces. 

Part of Qualitative Decrease System composition different from what it should be (in multi-component stream). 

The fact that LEIS provides quantitative information on the outer layer composition of multi-component materials makes this technique an extremely powerful tool for the characterization of catalysts. Figure 4.19 shows the LEIS spectrum of an alumina-supported copper catalyst, taken with an incident beam of 3 keV 4He+ ions. Peaks due to Cu, A1 and O and a fluorine impurity are readily recognized. The high intensity between about 40 and 250 eV is due to secondary (sputtered) ions. The fact that this peak starts at about 40 eV indicates that the sample has charged positively. Of course, the energy scale needs to be corrected for this charge shift before kinematic factors Ef/E-, are determined. 

Hence it is concluded that in multi-component silicate glasses, the presence or absence of a MAE is a complicated function of composition and environment, and not necessarily entirely dependent on the ratio of one alkali to the other. 

Although laser ablation is clearly becoming more popular (as shown in Fig. 9.1), it is difficult to produce fully quantitative data because of problems in matrix matching between sample and standard (see below and Section 13.3). There are also likely to be variations in ablation efficiency in multi-component mixtures, leading to over- or under-representation of particular phases of the sample. It is also unlikely that all ablation products will enter the plasma in the elemental state, or that different particle sizes produced by ablation will have the same compositions. Ablation products may, therefore, not be truly representative of the sample (Morrison et al. 1995, Figg et al. 1998). Additionally, limits of detection for most elements are approximately... 

Stoichiometric saturation defines equilibrium between an aqueous solution and homogeneous multi-component solid of fixed composition (10). At stoichiometric saturation the composition of the solid remains fixed even though the mineral is part of a continuous compositional series. Since, in this case, the composition of the solid is invariant, the solid may be treated as a one-component phase and Equation 6 is the only equilibrium criteria applicable. Equations 1 and 2 no longer apply at stoichiometric saturation because, owing to kinetic restrictions, the solid and saturated solution compositions are not free to change in establishing an equivalence of individual component chemical potentials between solid and aqueous solution. The equilibrium constant, K(x), is defined identically for both equilibrium and stoichiometric saturation. 

The intermediate phases formed in the various binary systems have been represented, in a first approximation, as point compounds. The points, which in the different binaries correspond to phases having the same composition and structure, have then been connected, defining multi-component ternary stability fields (in this case, line fields). On each horizontal line of this multi-diagram triangle the same overall composition is found (the same Mg content and the same total... 

One of the added merits of batch distillation is that more than one product may be obtained. Thus, a binary mixture of alcohol and water may be distilled to obtain initially a high quality alcohol. As the composition in the still weakens with respect to alcohol, a second product may be removed from the top with a reduced concentration of alcohol. In this way it is possible to obtain not only two different quality products, but also to reduce the alcohol in the still to a minimum value. This method of operation is particularly useful for handling small quantities of multi-component organic mixtures, since it is possible to obtain the different components at reasonable degrees of purity, in turn. To obtain the maximum recovery of a valuable component, the charge remaining in the still after the first distillation may be added to the next batch. 

A melt is a liquid or a liquid mixture at a temperature near its freezing point and melt crystallisation is the process of separating the components of a liquid mixture by cooling until crystallised solid is deposited from the liquid phase. Where the crystallisation process is used to separate, or partially separate, the components, the composition of the crystallised solid will differ from that of the liquid mixture from which it is deposited. The ease or difficulty of separating one component from a multi-component mixture by crystallisation may be represented by a phase diagram as shown in Figures 15.4 and 15.5, both of which depict binary systems — the former depicts a eutectic, and the latter a continuous series of solid solutions. These two systems behave quite differently on freezing since a eutectic system can deposit a pure component, whereas a solid solution can only deposit a mixture of components. 

In the case of multi-component alloys and compounds, the surface composition may also change in addition to surface relaxation and reconstruction. For instance, the first layer of (100) plane on the surface of a nickel-aluminiim alloy enriches itself with aliuninum whose atomic size is larger than nickel. Such an enrichment of some constituents on the soUd surface is called surface segregation [Van Hove, 1993]. It is abo known that surface active minor impurities of oxygen, phosphorus and sulfur in metallic iron segregate to the clean siirface of iron [Nii-Yoshihara,... 

For multi-component systems it seems intuitive that single-component diffusion and adsorption data would enable one to predict which component would be selectively passed through a membrane. This is only the case where molecular sieving is observed for all other separations where the molecules interact with one another and with the zeolite framework their behavior is determined by these interactions. Differences in membrane properties such as quahty, microstructure, composition and modification can also play a large role in the observed separation characteristics. In many cases, these properties can be manipulated in order to tailor a membrane for a specific apphcation or separation. 

FE data have been collected from the fracture of a wide variety of single and multi-component solids, ranging from single crystals of molecular solids to fiber-reinforced composites, and also from the peeling of adhesives 0-16 ). In this paper, we will restrict our attention to FE arising from the failure of polymer composites (fibrous and particulate), and the individual components thereof (fibers and matrix resins). 

The determination of individual binary equilibrium diagrams usually only involves the characterisation of a limited number of phases, and it is possible to obtain some experimental thermodynamic data on each of these phases. However, when handling multi-component systems or/and metastable conditions there is a need to characterise the Gibbs energy of many phases, some of which may be metastable over much of the composition space. 

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