Dependence on Composition

For a binary mixture of two components A and B in the gas phase, the mutual diffusion coefficient such as defined in 4.3.2.3, does not depend on composition. It can be calculated by the Fuller (1966) method ... 

Temary and quaternary semiconductors are theoretically described by the virtual crystal approximation (VGA) [7], Within the VGA, ternary alloys with the composition AB are considered to contain two sublattices. One of them is occupied only by atoms A, the other is occupied by atoms B or G. The second sublattice consists of virtual atoms, represented by a weighted average of atoms B and G. Many physical properties of ternary alloys are then expressed as weighted linear combinations of the corresponding properties of the two binary compounds. For example, the lattice constant d dependence on composition is written as ... 

There is also a possibility of preparing mixed III-V nitride alloys, e.g. GaAs connecting tire two sets of semiconductor materials. Their gap dependence on composition is tire subject of active research. 

Catalyst performance depends on composition, the method of preparation, support, and calcination conditions. Other key properties include, in addition to chemical performance requkements, surface area, porosity, density, pore size distribution, hardness, strength, and resistance to mechanical attrition. 

Hydrocarbon resins are used extensively as modifiers in adhesives, sealants, printing inks, paints and varnishes, plastics, road marking, flooring, and oil field appHcations. In most cases, they ate compounded with elastomers, plastics, waxes, or oils. Selection of a resin for a particular appHcation is dependent on composition, molecular weight, color, and oxidative and thermal stabiHty, as weU as cost. A listing of all hydrocarbon resin suppHers and the types of resins that they produce is impractical. A representative listing of commercially available hydrocarbon resins and their suppHers is included in Table 6. 

Extmsion is a common way for soHd products such as plastics to emerge from closed manufacturing systems. Normally a polymer is hot when extmded and may contain additives and oligomers that are volatile at elevated tempera-tures. The result is Aiming at the extmder head. These fumes can result in employee annoyance, housekeeping problems, and, at worst, depending on composition, health ha2ards. 

Upon reheating cold-worked steel to the recrystallization temperature (- 450° C) or above, depending on composition, extent of cold working, and other variables, the original microstmcture and properties may be substantially restored. 

The flow sheet in Figure 3 iHustrates cadmium recovery from cadmium-bearing fumes. Depending on composition, the fume may have to be roasted with or without sulfuric acid or oxidi2ed using sodium chlorate or chlorine in order to convert cadmium into a water- or acid-soluble form and to... 

If pure, the carbides of Groups 1 and 2 are characterized by their transparency and lack of conductivity. The carbides of Group 3, ie. Sc, Y, the lanthanides, and the actinides, ate opaque. Some, depending on composition, show metallic luster and electroconductivity. The cation may exist in the MC2 phases of this group, and the remaining valence electron apparendy imparts pardy metaUic character to these compounds. 

Values for the Poisson s ratio of ice are highly dependent on composition, stmcture, and strain rate (4). 

Barrier Layers. Depending on composition, barrier layers can function simply as spatial separators or they can provide specified time delays by swelling at controlled rates or undergoing reactions such as hydrolysis or dissolution. Suitable barrier materials include cellulose esters and water-permeable polymers such as gelatin and poly(vinyl alcohol) (see Barrier polymers). 

Properties of Denture-Base Matena/s. Physical properties of acryflc denture-base materials are given in Table 12 (204). Mechanical properties of denture bases can vary considerably, and depend on composition, mode of polymerization, and degree of interaction with the oral environment. 

All eight parameters depend on composition moreover, parameters Co, b, and y are for some applications treated as functions of X By Eq. (4-171), the residual Gibbs energy is... 

Since activity coefficients have a strong dependence on composition, the effect of the solvent on the activity coefficients is generally more pronounced. However, the magnitude and direc tion of change is highly dependent on the solvent concentration, as well as the liquid-phase interactions between the key components and the solvent. The solvent acts to lessen the nonideahties of the key component whose liquid-phase behavior is similar to the solvent, while enhancing the nonideal behavior of the dissimilar key. 

Our researches of a method fire assay (FA) of ores have shown that the losses of noble metals (NM) in scoria s FA hardly depend on composition of used fusion mixture. Usage of ultrasonic (US) oscillations of low frequency allows lowering on 50-100° temperature FA, to reduce time in 3-4 times. Even under unfavorable conditions thus the extent of extraction NM is conserved at FA on NiS (Ni S ) or Sn and is augmented at usage as a collector Pb or Cu. 

This model is appropriate for random mixtures of elements in which tire pairwise bonding energies remain constant. In most solutions it is found that these are dependent on composition, leading to departures from regular solution behaviour, and therefore the above equations must be conhned in use to solute concentrations up to about 10 mole per cent. 

B. 4BmvBl,4 1,4-Polybutadiene (low vinyl) 1,2-Polybu ta diene (low, 34 (or low isopropenyl)] (see comments above) Polyethylene Poly(ethylene-co- butylene) Properties dependent on composition and architecture... 

IBI 1,4-Polyisoprene 1,4-Polybutadiene Poly(ethylene-co- propylene Polyethylene Inverse block polymer— properties dependent on composition... 

Many liquid alloys, in particular, the alkali-group IV alloys, exhibit (Zintl) anion clustering and show strong effects of compound formation. A typical example of such Zintl systems are sodium-tin alloys. In the solid NaSn crystal the Zintl anions Sn appear [1]. An interesting question is the stability of these anions in the liquid. Furthermore, the electrical conductivity of these alloys shows a strong dependence on composition [2] For the limiting (sodium-rich or tin-rich) cases a metallic (small) conductivity appears, but for the nearly equimolar compositions a semi-metallic behavior - with a considerably smaller conductivity - is observed. 

In the case of Ni-Al the martensitic transformation occurs in a composition range between 62 and 67 at.% Ni where the excess Ni is accommodated randomly on the A1 sublattice. The resulting c/a ratio of the LIq structure is around 0.85, depending on composition. Below 63 at.% Ni the martensite structure has a (52) sequence of close packed planes (Zhdanov notation) which is currently denoted as 14M (formerly as 7R). At higher Ni contents this typical sequence is lost and the martensite plates are simply internally twinned without a specific periodicity. 

The mechanical properties of wrought alloys depend on composition and metallurgical condition. At the extremes, annealed pure copper has a tensile strength of 180MN m and a hardness of 40 Hy, and heat-treated beryllium copper can have a tensile strength of 1 300 MN m and a hardness of 390 Hy. Summaries of typical properties of some of the more important wrought and cast copper alloys are given in Tables 4.9 and 4.10. 

Here the first term is the free energy of pure crystalline lead, the second term an assumed linear dependence on composition, and the third term the free energy of mixing lead and thallium in the atomic positions 0, J J, 0, J and J, J, 0 of the unit cube. Curves representing these expressions are shown in Fig. 7. The value of a... 

We have considered volume changes resulting from density changes in liquid and gaseous systems. These volume changes were thermodynamically determined using an equation of state for the fluid that specifies volume or density as a function of composition, pressure, temperature, and any other state variable that may be important. This is the usual case in chemical engineering problems. In Example 2.10, the density depended only on the composition. In Example 2.11, the density depended on composition and pressure, but the pressure was specified. 

The design equations for a CSTR do not require that the reacting mixture has constant physical properties or that operating conditions such as temperature and pressure be the same for the inlet and outlet environments. It is required, however, that these variables be known. Pressure in a CSTR is usually determined or controlled independently of the extent of reaction. Temperatures can also be set arbitrarily in small, laboratory equipment because of excellent heat transfer at the small scale. It is sometimes possible to predetermine the temperature in industrial-scale reactors for example, if the heat of reaction is small or if the contents are boiling. This chapter considers the case where both Pout and Tout are known. Density and Q ut wiU not be known if they depend on composition. A steady-state material balance gives... 

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