Specific property volume

The resistance of a segment of the path described above is proportional to its length, iaversely proportional to its cross-sectional area, and proportional to a specific property of the material of the segment called resistivity or volume resistivity, ie ... 

In this paper, the electronic structure of disordered Cu-Zn alloys are studied by calculations on models with Cu and Zn atoms distributed randomly on the sites of fee and bcc lattices. Concentrations of 10%, 25%, 50%, 75%, and 90% are used. The lattice spacings are the same for all the bcc models, 5.5 Bohr radii, and for all the fee models, 6.9 Bohr radii. With these lattice constants, the atomic volumes of the atoms are essentially the same in the two different crystal structures. Most of the bcc models contain 432 atoms and the fee models contain 500 atoms. These clusters are periodically reproduced to fill all space. Some of these calculations have been described previously. The test that is used to demonstrate that these clusters are large enough to be self-averaging is to repeat selected calculations with models that have the same concentration but a completely different arrangement of Cu and Zn atoms. We found differences that are quite small, and will be specified below in the discussions of specific properties. 

An alternative is to consider the value of the thermodynamic property per unit mass. Such quantities are called specific properties. Thus the specific volume is the volume per unit mass. It is the reciprocal of the density and is an intensive property. 

Particle Size Development. Now that a general total property balance equation has been developed (equation (II-9)), one can use it to obtain ordinary differential equations (ode s) which will describe particle size development. What is needed with equation (II-9) is an expression for dp(t,t)/dt, where p denotes a specific property of the system (e.g. particle size). Such an expression can be written for the rate of change of polymer volume in a particle of a certain class. The analysis, which is general and described in Appendix III, will finally result in a set of ode s for Np(t), Dp(t), Ap(t) and Vp(t). 

This is the relationship we seek. It says that the rate of change of a property / defined over a system volume is equal to the rate of change for the control volume plus a correction for matter that carries / in or out. This follows since v w is the relative velocity of matter on the boundary of the control volume. If v — w = 0, no matter crosses the boundary. As we proceed in applying Equation (3.12) to the conservation laws and in identifying a specific property for/, we will bring more meaning to the process. We will consider the system to be composed of a fluid, but we need not be so restrictive, since our analysis will apply to all forms of matter. 

The apparent density 5 (g/cm3) is usually measured using mercury as a pycnometric fluid. Mercury does not wet most of the solids and, thus, does not penetrate pores until pressure is applied. Mercury is not the only choice highly dispersed powders can serve as a guest fluid with the same penetration properties as well [55], Reciprocal to S is the specific apparent volume of PS, which is equal to the sum of the volumes of the pores and solid phase (e.g., the total volume of a granule shown in Figure 9.17a), and is obviously related to the mass of a PS. Relation between true and apparent density and porosity was considered in Problem 4. 

Considering other families of similar compounds, the contributions given by Guillermet and Frisk (1992), Guillermet and Grimvall (1991) (cohesive and thermodynamic properties, atomic average volumes, etc. of nitrides, borides, etc. of transition metals) are other examples of systematic descriptions of selected groups of phases and of the use of special interpolation and extrapolation procedures to predict specific properties. 

Any characteristic of a system is called a property. The essential feature of a property is that it has a unique value when a system is in a particular state. Properties are considered to be either intensive or extensive. Intensive properties are those that are independent of the size of a system, such as temperature T and pressure p. Extensive properties are those that are dependent on the size of a system, such as volume V, internal energy U, and entropy S. Extensive properties per unit mass are called specific properties such as specific volume v, specific internal energy u, and specific entropy. s. Properties can be either measurable such as temperature T, volume V, pressure p, specific heat at constant pressure process Cp, and specific heat at constant volume process c, or non-measurable such as internal energy U and entropy S. A relatively small number of independent properties suffice to fix all other properties and thus the state of the system. If the system is composed of a single phase, free from magnetic, electrical, chemical, and surface effects, the state is fixed when any two independent intensive properties are fixed. 

In the most general sense, all plastics are engineering materials, in that they offer specific properties which we judge quantitatively in the design of end-use applications. Among die large-volume established thermoplastics, we should certainly pay tribute to the engineering performance of the polyolefins, polystyrene, impact styrene, ABS, vinyls, acrylic, and cellulosic plastics. 

A more detailed description of specific properties of polymeric cholesterics is given in a review of Rehage and Finkelmann 27) of this volume... 

Standard test method for rubber property-volume resistivity of electrically conductive and antistatic products Specification for electrical properties of conducting and antistatic products made from flexible polymeric material... 

Beside the chemical composition, the crystalline structure of the mineral has an important effect on the adsorption ability of its surface. This is due to the fact that lattice bindings are usually not equivalent and space disproportions occur, so that fission surface areas have specific properties. Typical examples are layer lattices of graphite or talc where the main valences proceed in the layer plains whereas these are interconnected with feeble valences. Fission areas of such minerals are hydrophobic. The effect of the structure on adsorption properties of a mineral surface increases with increasing adsorption density and with decreasing force of the adsorption binding of the solid phase5. A crystalline lattice contains structural defects (which include physical and chemical surface imperfections and deficiencies in the volume phase) which can influence the chemical reactivity of a crystal surface. 

Specifically, this volume focuses on the synthesis, processing, and structural tailoring of nanocrystalline and nanoporous materials. Nanocrystalline materials possess unique hybrid properties characteristic of neither the molecular nor the bulk solid-state limits and may be confined in nanometersized domains in one, two, or three dimensions for unusual size-dependent behavior. Nanoporous materials, characterized by well-defined pores or cavities in the nanometer size regime and controlled pore diameter and structure, give rise to unique molecular sieving capabilities and ultrahigh internal surface areas. Nanoporous structures also act as hosts and templates for the fabrication of quantum dots and quantum wires. 

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