Property specific

The specific properties of nanostructured materials can have two different possible origins  

For a recent comprehensive review of the basic principles of the origin of the properties of nanostructured materials, see [3.5]. 

A specific property is a system constitutive property that depends only on the nature of a material and not on its extent (size and shape). The interest to use specific properties in modeling a system is obvious because it allows the prediction of a response to a perturbation knowing the material that constitutes the system, and, conversely, it allows the identification of a material by characterizing some of its specific properties. 

Besides this practical interest, another more fundamental reason for looking after specific properties is to put into evidence the existence of invariant properties or parameters of our world. Together with the notions of symmetry and conservation, invariance is one of the fundamental concepts that are the ingredients of our rational understanding of nature. 

Understanding Physics and Physical Chemistry Using Formal Graphs 

FIGURE 3.2 The nine possibilities for a system constitutive property to be specific, according to the number 

The question remains as to how to choose the right one among specific properties, since there are always several possibilities. There is no simple answer to this question, because it depends on the physics of the phenomenon represented by the reduced property. The Formal Graph theory has no peculiar point of view on this question and a better understanding will emerge from the various case 

Paints must be easy to apply, and to be practical engineering materials, there must be a minimum of lost time or additional expense when painting. Paints must also be applied to the substrate in the specific film thickness, dry in the specified time to the desired appearance, and possess the necessary specific properties. 

When properly applied, the cured or dried film of paint should have all the film properties advertised by the paint manufacturer. This is film integrity, or uniformity. There must be no weak spots (holidays) in the film caused by imperfect drying or curing. 

To function as engineering materials, paints must be consistent in quality from can to can, batch to batch, and shipment to shipment. Color, viscosity, application properties, durability, etc., must all comply with specifications. 

The following are speeific properties that should be taken into account when speeifying aeeeptable paint standards for a particular use. 

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The products could be classified as a function of various criteria physical properties (in particular, volatility), the way they are created (primary distillation or conversion). Nevertheless, the classification most relevant to this discussion is linked to the end product use LPG, premium gasoline, kerosene and diesel oil, medium and heavy fuels, specialty products like solvents, lubricants, and asphalts. Indeed, the product specifications are generally related to the end use. Traditionally, they have to do with specific properties octane number for premium gasoline, cetane number for diesel oil as well as overall physical properties such as density, distillation curves and viscosity. 

Piezocomposite transducers are an advancement of piezoelectric ceramics. Instead of the classic piezoceramic material, a compound of polymer and piezoceramic is used for the composite element to improve specific properties. The 1-3 structure, which is nowadays mostly used as transducer material, refers to parallel ceramic rods incorporated in an epoxy-resin matrix (see Fig. 1). 

Many phenomena ask for local, site-specific properties of a molecule such as the partial charge on a specific atom in a molecule or the hydrogen bond donor ability of a certain OH group. It would be highly desirable to have methods as simple as an additivity model to estimate such site-specific molecular properties. 

Semiempirical methods are parameterized to reproduce various results. Most often, geometry and energy (usually the heat of formation) are used. Some researchers have extended this by including dipole moments, heats of reaction, and ionization potentials in the parameterization set. A few methods have been parameterized to reproduce a specific property, such as electronic spectra or NMR chemical shifts. Semiempirical calculations can be used to compute properties other than those in the parameterization set. 

The first section of this chapter discusses various ways that chemical properties are computed. Then a number of specific properties are addressed. The final section is on visualization, which is not so much a property as a way of gaining additional insight into the electronic structure and motion of molecules. 

Specific breakage rate Specific conductivity Specific ion electrode Specific properties... 

Applications. For use as a gaseous dielectric, other specific properties are needed in addition to high breakdown strength, and a compromise must be made between electrical and mechanical requirements. Desirable properties include low toxicity, thermal stabiUty toward materials of constmction. 

The properties that are achieved in commercial stmctural foams (density >0.3 g/cm ) are shown in Table 3. Because these values depend on several stmctural and process variables, they can be used only as general guidelines of mechanical properties from these products. Specific properties must be deterrnined on the particular part to be produced. A good engineering guide has been pubHshed (103). 

The cross-sectional area of the wick is deterrnined by the required Hquid flow rate and the specific properties of capillary pressure and viscous drag. The mass flow rate is equal to the desired heat-transfer rate divided by the latent heat of vaporization of the fluid. Thus the transfer of 2260 W requires a Hquid (H2O) flow of 1 cm /s at 100°C. Because of porous character, wicks are relatively poor thermal conductors. Radial heat flow through the wick is often the dominant source of temperature loss in a heat pipe therefore, the wick thickness tends to be constrained and rarely exceeds 3 mm. 

Additives are used to provide a specific property. For example, a wax provides mb resistance in the printed film or a surfactant reduces foam generation in the fountain. 

The alcohols, proprietary denatured ethyl alcohol and isopropyl alcohol, are commonly used for E-type inks. Many E-type inks benefit from the addition of small amounts of ethyl acetate, MEK, or normal propyl acetate to the solvent blends. Aromatic hydrocarbon solvents are used for M-type inks. Polystyrene resins are used to reduce the cost of top lacquers. T-type inks are also reduced with aromatic hydrocarbons. Acryflc resins are used to achieve specific properties for V-type inks. Vehicles containing vinyl chloride and vinyl acetate copolymer resins make up the vinyl ink category. Ketones are commonly used solvents for these inks. 

In addition to polyamide, lamination inks ordinarily contain modifiers such as polyketone resin, plasticizer, and wax to impart specific properties such as block resistance and increased bond strength. Because laminating inks are usually reverse-side printed and end-up sandwiched between films, gloss is not a primary requirement. Water-base laminating inks that will meet the U.S. EPA emission requirements and have the correct functional properties are currently under development. 

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 ... 

Fillers. These are used to reduce cost in flexible PVC compounds. It is also possible to improve specific properties such as insulation resistance, yellowing in sunlight, scuff resistance, and heat deformation with the use of fillers (qv). Typical filler types used in PVC are calcium carbonate, clays, siHca, titanium dioxide, and carbon black. 

Most commercial processes involve copolymerization of ethylene with the acid comonomer followed by partial neutralization, using appropriate metal compounds. The copolymerization step is best carried out in a weU-stirred autoclave with continuous feeds of all ingredients and the free-radical initiator, under substantially constant environment conditions (22—24). Owing to the relatively high reactivity of the acid comonomer, it is desirable to provide rapid end-over-end mixing, and the comonomer content of the feed is much lower than that of the copolymer product. Temperatures of 150—280°C and pressures well in excess of 100 MPa (1000 atm) are maintained. Modifications on the basic process described above have been described (25,26). When specific properties such as increased stiffness are required, nonrandom copolymers may be preferred. An additional comonomer, however, may be introduced to decrease crystallinity (10,27). 

The extremely unusual physical properties of the rare earths are the reason for a number of industrial appHcations where no other element can suffice. Furthermore, although RE chemical properties are rather similar to those of the alkaline earths, some specific properties have pushed the rare earths into large industrial developments. 

Monomers. A wide variety of monomers can be used, and they are chosen on the basis of cost and abiUty to impart specific properties to the final product. Water solubiUties of iadustriaHy important monomers are shown ia Table 1 (38). The solubiUty of the monomer ia water affects the physical chemistry of the polymerization. Functional monomers like methacrylic and acryUc acid, infinitely soluble ia water, are also used. These monomers impart long-term shelf stabiUty to latices by acting as emulsifiers. The polymerization behavior of some monomers, such as methacrylic acid, as well as the final latex properties are iafiuenced by pH. For optimum results with these acids, polymerization is best performed at a pH of ca 2. After polymerization, the latex is neutralized to give adequate shelf stabiUty at tractable viscosities. 

Lime Oil. This oil is obtained from the fmit Citrus aurantijolia Swingle the Key, Mexican, or West Indian lime or C latijolia Tanaka, the Persian lime, either by steam distillation or expression. Either the entire cmshed fmit or only the peel may be used, depending on the specific properties desired. A typical commercial distilled lime oil contains the constituents shown in Table 10 (25). 

Papermaking additives can be categorized either as process additives or as functional additives. Process additives are materials that improve the operation of the paper machine, such as retention and drainage aids, biocides, dispersants, and defoamers they are primarily added at the wet end of the paper machine. Functional additives are materials that enhance or alter specific properties of the paper product, such as fillers (qv), sizing agents, dyes, optical brighteners, and wet- and dry-strength additives they may be added internally or to the surface of the sheet. 

Other Reactants. Other reactants are used in smaller amounts to provide phenoHc resins that have specific properties, especially coatings appHcations. Aniline had been incorporated into both resoles and novolaks but this practice has been generally discontinued because of the toxicity of aromatic amines. Other materials include rosin (abietic acid), dicyclopentadiene, unsaturated oils such as tung oil and linseed oil, and polyvalent cations for cross-linking. 

The coarse, nonpigmentary cmdes are particle si2e reduced by a variety of processes to obtain pigmentary CPC. Since CPCs are utili2ed in a variety of industries and a host of appHcations, the specific property requirements vary widely. A large number of special-purpose types are commercially available designed to provide optimal properties for specific appHcations. 

Other amino resias used ia the textile iadustry for rather specific properties have iacluded the methylo1 derivatives of acrylamide (46), hydantoia [461-79-3] (47), and dicyandiamide (48). 

Hydrocarbon Solvents. Most hydrocarbon solvents are mixtures. Few commercial hydrocarbon solvents are single compounds. Toluene is an exception. Hydrocarbon solvents are usually purchased and suppHed on specification. The most important specification properties are distillation range, solvency as expressed by aniline cloud poiat and Kauri-Butanol (KB) value, specific gravity, and dash poiat. Composition requirements such as aromatic content and benzene concentration are also important ia many appHcations. 

Hydrocarbon solvents marketed by each manufacturer differ ia composition from those of other manufacturers, even if the specification properties are similar. This means that hydrocarbon solvents are not specified on the basis of molecular content. The composition of a hydrocarbon solvent depends on the cmde feed to the process as well as the specific process steps the solvent undergoes duriag manufacture. Because each manufacturer uses a different feed and a somewhat different manufacturiag scheme, hydrocarbon solvents differ somewhat ia thek properties, even ia situations where the solvent performs the same. 

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