Nomenclature particle systems

The Schmidt number is the ratio of kinematic viscosity to molecular diffusivity. Considering liquids in general and dissolution media in particular, the values for the kinematic viscosity usually exceed those for diffusion coefficients by a factor of 103 to 104. Thus, Prandtl or Schmidt numbers of about 103 are usually obtained. Subsequently, and in contrast to the classical concept of the boundary layer, Re numbers of magnitude of about Re > 0.01 are sufficient to generate Peclet numbers greater than 1 and to justify the hydrodynamic boundary layer concept for particle-liquid dissolution systems (Re Pr = Pe). It can be shown that [(9), term 10.15, nomenclature adapted]... 

The field of protoplanetary dust size distributions and properties can be confusing. We therefore begin by briefly reviewing the most common definitions and assumptions. Owing to the nature of astrophysical observations, extrasolar dust particles are usually described in terms of their optical properties. This is generally not the case for Solar System material, which is available to direct laboratory studies. This gives rise to potentially confusing differences in nomenclature. 

As it is well known, the contacts between drops (in emulsions), solid particles (in suspensions) and gas bubbles (in foams) are accomplished by films of different thickness. These films, as already discussed, can thin, reaching very small thickness. Observed under a microscope these films reflect very little light and appear black when their thickness is below 20 nm. Therefore, they can be called nano foam films. IUPAC nomenclature (1994) distinguishes two equilibrium states of black films common black films (CBF) and Newton black films (NBF). It will be shown that there is a pronounced transition between them, i.e. CBFs can transform into NBFs (or the reverse). The latter are bilayer formations without a free aqueous core between the two layers of surfactant molecules. Thus, the contact between droplets, particles and bubbles in disperse systems can be achieved by bilayers from amphiphile molecules. 

The Kennedy s nomenclature has been derived for straightforward cases of initiating H or generation. When the structure of the initiating particle is unknown, the same logical approach cannot be used to discern between initiator and co-initiator. It is even more important, according to this nomenclature, cationic polymerizations would be initiated by Lewis bases, and only co-initiated by Lewis acid. This clearly contradicts all experience. Many systems are known that can be cationically polymerized in the presence of a Lewis acid, without any co-initiator. 

In addition to the specific textural class of individual particles, the range of particle sizes common in naturally-occurring lake sediments necessitates use of an additional sediment mixture classification system to actually name the material. Several such systems are in common use (Fig. 2), and, as with sediment compositional classification systems, there is little uniformity of practice or nomenclature. 

With their two-phase systems (e.g., polymeric matrix and inorganic filler), composites permit enhancement of mechanical or dielectric properties, owing to the high interfacial area between matrix and filler particles. The appeal of nanocomposites discussed in recent literature [Schaefer and Justice, 2007] explains the wide variety of used fillers, with dimensions ranging from 10 nm to about 1 fx.m. This range is well outside that suggested by the lUPAC nomenclature for nanoparticles (nanoparticles must have at least one dimension d<2nm mesoparticles with 2 50 nm), but to be consistent with the data cited in this chapter, they all will be termed nanoparticles, regardless of size. 

The traditional definition of emulsions (1) as consisting of two liquids, of which one is dispersed in the other in the form of macroscopic droplets, was modified by the lUPAC Commission for Nomenclature (2) to include lyotropic liquid crystals. This change was justified by the fact that a large number of commercial emulsions within the areas of foods, pharmaceutics, and personal care contain such structures. Commercial emulsions frequently also contain solid particles, but such systems are usually not called emulsions, but rather emulsions-suspensions to avoid having the term emulsions covering the majority of dispersed systems. 

As is the case in most discussions of interfacial systems and their applications, definitions and nomenclature can play a significant role in the way the material is presented. The definition of an emulsion to be followed here is that they are heterogeneous mixtures of at least one immiscible liquid dispersed in another in the form of droplets, the diameters of which are, in general, greater than 0.1 (.m. Such systems possess a minimal stability, generally defined rather arbitrarily by the application of some relevant reference system such as time to phase separation or some related phenomenon. Stability may be, and usually is, enhanced by the inclusion of additives such as surfactants, finely divided solids, and polymers. Such a definition excludes foams and sols from classification as emulsions, although it is possible that systems prepared as emulsions may, at some subsequent time, become dispersions of solid particles or foams. 

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