Volumetric phenomenon

Reservoir capacity is, in our view, an attempt by a polymer to dissolve. Because of cross-linking and molecular weight, the system does not fully dissociate into a true solution. Rather than dissolving in the normal sense, the polymer is said to swell in the solvent. Absorption of a solvent, water or organic, is a volumetric phenomenon controlled by the relative polarities of polymer and solvent. A nonpolar backbone is preferred for absorbing nonpolar solvents. The molecule we call polyurethane, however, is not entirely nonpolar but is close enough for use as an absorbing matrix. 

Radiation is a volumetric phenomenon, and all solids, liquids, and gases emit, absorb, or transmit radiation to varying degrees. However, radiation is... 

Note that heat generation is a volumetric phenomenon. That is, it occurs throughout the body of a medium. Therefore, the rate of heat generation in a medium is usually specified per unit volume and is denoted by e f , whose unit is W/m or Btu/h ft . 

Although radiation can travel in a vacuum, it originates from matter. All forms of matter emit radiation through the mechanisms of electronic transitions and lattice vibrations. In most solids and liquids, radiation emitted from the interior is strongly absorbed by adjoining molecules. Therefore, radiation from these materials can be treated as a surface phenomenon. Radiation in gases and some semitransparent sohds and liquids, however, must be treated as a volumetric phenomenon. 

Even if conductivity results of CNT/polymer nanocomposites are commonly reported in terms of wt%, mainly because of lack of precise CNT density values, percolation is considered to be a volumetric phenomenon. In an attempt to fairly compare conductivity results obtained for systems containing either SWCNTs or MWCNTs dispersed in a given polymer matrix, the percolation threshold values of the various nanocomposites series were calculated in terms of vol% CNT. See ref. [28] for the details of the calculation. 

All states of matter (solids, liquids, and gases) emit thermal radiation. For gases and for semi-transparent solids, such as glass and salt crystals at elevated temperatures, emission is a volumetric phenomenon. That is, radiation emerging from a... 

FIGURE I Retention times of two analytes using various mobile preparations vs. pump blend. Note that procedures A and D are almost equivalent while column B or C (using volumetric flasks) yields retention times which are either too high or too low depending on whether methanol or water is filled first.This phenomenon is caused by the negative volume of mixing. Procedure A is recommended for all mobile phase preparation. 

The consequences of this type of activated physical adsorption is not only that the quantity adsorbed can lie off the isotherm but also that the measured quantity of adsorption is far less than the equilibrium value. No experiments have been conducted to illustrate whether or not the quantity adsorbed lies within the hysteresis loop. The occasional failure of the vacuum volumetric method to agree with the dynamic method, which is not subject to any pressure overshoot, may in part be attributed to this phenomenon. 

Both the volumetric and gravimetric apparatus are subject to this effect. Data acquired at low pressures must be corrected for thermal transpiration. The continuous flow method is not subject to this phenomenon. 

The dosing requirement of gravimetric and volumetric apparatus can lead to pressure overshoot which may produce data off the isotherm in the hysteresis region. The continuous flow method is not susceptible to this phenomenon. 

Choking is a phenomenon that occurs in high speed compressible flow (e.g. in relief systems). It occurs because, as the pressure falls along a pipe or through a nozzle, the fluid density decreases. This, means that the volumetric flow rate and, hence, the velocity increases (because the mass flow is constant). Choking occurs when the downstream pressure is reduced to the point where the velocity cannot increase any more. This effectively limits the maximum velocity and, hence, flow rate of the fluid. 

As the velocity of the gas is increased furtlier, the bed continues to expand and its height increases with only slight increase in the pressure drop. As the velocity of the gas is further increased, the bed continues to expand and its height increases, whereas the concentration of particles per unit volume of the bed decreases. At a certain velocity of the fluidizing medium, known as the entrainment velocity, particles are carried over by the gas. This phenomenon is called entrainment. When the volumetric concentration of solid particles is uniform throughout the bed at all times, the fluidization is termed particular. When the concentration of sohds is... 

In volumetric analysis, hydrophilic colloids alter the end point, e.g., in a titration of HC1 and NaOH, the amount of deviation in the end point is increased with increasing amounts of colloids. In the volumetric estimation of silver by Mohr s method, the phenomenon of adsorption comes into being. 

The volumetric properties are extremely important for nearly every phenomenon or process. The main volumetric properties are ... 

The major process for poly(vinyl chloride) production is the suspension system. Typical reaction temperatures are 50-65 C. As the reaction proceeds, a conversion ( 76%) is reached at which the only monomer left in the system is that absorbed in the polymer particles. This occurs when the monomer concentration is about 30 wt % in the particles. The occurrence of this phenomenon is signaled by a drop in the reactor pressure. Normal pressures in the autoclaves are initially about 150 psig (pounds per square inch, gauge), and it is usual to carry out polymerizations until the pressure drops to about 20-70 psig, depending on the reaction temperature. Water may be injected into the reaction vessel as the polymerization proceeds, to compensate for the volumetric contraction between monomer and polymer. This also helps prevent the reaction mixture from becoming too viscous. As well, the water addition enhances the cooling capacity of the reactor because it increases the heat transfer area on the walls. 

As acknowledged in the Trovarelli s review work (61), data obtained from the conventional volumetric studies cannot, in general, be interpreted in a straightforward manner. Even if excluded the occurrence of a SMSNike phenomenon, there are a number of side effects, which may very much complicate the interpretation of these chemisorption data. Accordingly, the H(CO)/M ratios thus determined should be considered, in principle, as apparent values rather than a true estimate of the metal dispersion. Thus, it is known that ceria shows a poor textural stability, particularly... 

Flow models have been used also to derive expressions for velocity profiles and volumetric flow rates in tube and channel flows, and in the analysis of heat transfer phenomenon. Numerous flow models can be encountered in the rheology literature and some from the food rheology literature are listed in Table 2-1. Also, here those models that have found extensive use in the analysis of the flow behavior of fluid foods are discussed. Models that account for yield stress are known as viscoplastic models (Bird et al., 1982). For convenience, the flow models can be divided in to those for time-independent and for time-dependent flow behavior. 

The most important effect of combustion chamber deposits is that they make the engine more knock-prone as they build up. This is quantified as an octane requirement increase (ORI), and it typically reaches 5-10 octane numbers. Several mechanisms probably play a part in the phenomenon. Principally these are volumetric, thermal and chemical. The volumetric effect is the increase in the compression ratio caused by the volume of the deposits. This has been estimated [147] to be responsible for only about... 

The essential parts of a volumetric apparatus are a closed system of known volume, a source of adsorbate and a pressure measuring device. This type of apparatus is more commonly used for the determination of adsorption isotherms, but kinetics can be measured provided that the adsorbent surface is large and the response of the pressure measuring device is much faster than the rate of adsorption. These criteria are usually only satisfied by powders or films which show activated adsorptions. Bond has discussed the phenomenon of activated adsorption. Although the results may often be ascribed to contamination or incorporation into the bulk of the material, in other instances a genuine activated chemisorption is found. 

The nonideal chemical or physical behavior of the reagents and reactions on which an analysis is based often introduces systematic method errors. Such sources of nonideality include the slowness of some reactions, the incompleteness of others, the instability of some species, the nonspecificity of most reagents, and the possible occurrence of side reactions that interfere with the measurement process. For example, a common method error in volumetric analysis results from the small excess of reagent required to cause an indicator to undergo the color change that signals completion of the reaction. The accuracy of such an analysis is thus limited by the very phenomenon that makes the titration possible. 

Thermal expansion is another fundamental property of materials that originates from the reinforcement of atomic vibrations, with an essential anharmonic component, leading to changing interatomic distances with temperature. This phenomenon can be quantified by using either a volumetric (tty) or linear (aJ coefficient of thermal expansion (CTE) ... 

---