Dispersions processing steps

Concentrates are made in the same manner as dispersions but often with less work placed into the colorant—vehicle system, thus higher yields and rates are obtained and a lower cost product is made. Usually, the concentrate goes through an additional processing step with the resin in which additional energy is provided to the system, thus ensuring more dispersion. 

Equation (1) can be used in a general way to determine the variance resulting from the different dispersion processes that occur in an LC column. However, although the application of equation (1) to physical chemical processes may be simple, there is often a problem in identifying the average step and, sometimes, the total number of steps associated with the particular process being considered. To illustrate the use of the Random Walk model, equation (1) will be first applied to the problem of radial dispersion that occurs when a sample is placed on a packed LC column in the manner of Horne et al. [3]. 

This example of the use of the Random Walk model illustrates the procedure that must be followed to relate the variance of a random process to the step width and step frequency. The model will also be used to derive an expression for other dispersion processes that take place in a column. 

The Dispersion Process. The calculation methods to predict ambient pollutant concentrations are based on a two-step process for dispersion. First, the pollutant gases from a stack rise as a result of their own conditions of release, and then they are dispersed approximately in accordance with a Gaussian or normal distribution. 

Sequence for Special Metallic Lacquers For some special metallic lacquers it is necessary to perform a pre-dispersion of the basic materials. For this process an additional dose distributor is required for the pre-dispersion resources. The assignment of the dose distributor starts at the same time as the assignment of the pre-dispersion resource. When the pre-dispersion process has finished the procedures on the dose spinner and on the mixer begin. The following production steps are equal to those of the standard production sequence (see Figures 4.8 and 4.9). 

The complex mechanism underlying this dispersion process of the epsilon modification of phthalocyanine blue is conceptually resolved into three steps ... 

The particle size of a pigment, however, has an impact not only on those steps within the dispersion process in which pigment agglomerates are broken down. It also affects retroactive processes, such as reagglomeration, flocculation, and rubout effects [19]. Reagglomeration (Sec. 1.5) occurs if the pigment particles are not covered adequately by the binder. Flocculates (Sec. 1.5) are loose associations... 

A variety of processing steps may then be carried out. Examples are compression molding, injection molding, transfer molding, extrusion, calendering, dispersion coating, and blowing into foams.5,79... 

Each processing step is linked to the next. Therefore the different steps cannot be considered independently from each other. For example, coloring processes already take place in the plastification zone, the incorporation of fibers added to the melt takes place not only in the designated dispersing zone but also in the discharge zone and in partially filled screw channels. 

Depending on the subsequent process steps, achieving 100% melting at the end of the plastification zone may not be mandatory. Solid particles still present after the plastification zone can be melted in subsequent zones, e. g., in the dispersion or discharge zones. Figure 4.6 illustrates a typical melting profile along a plastification zone. 

The emulsion enters the desalter vessel where a high-voltage electrostatic field is applied. The electrostatic field causes the dispersed water droplets to coalesce, agglomerate, and settle to the lower portion of the vessel. The various contaminants from the crude oil concentrate in the water phase. The salts, minerals, and other water-soluble impurities are discharged from the settler to the effluent system. Clean, desalted hydrocarbon product flows from the top of the settler and is ready for the next processing step. 

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