Dispersion quality

The criterion of maintaining equal power per unit volume has been commonly used for dupHcating dispersion qualities on the two scales of mixing. However, this criterion would be conservative if only dispersion homogeneity is desired. The scale-up criterion based on laminar shear mechanism (9) consists of constant > typical for suspension polymerization. The turbulence model gives constant tip speed %ND for scale-up. 

FIGURE 33.3 Dispersive component of surface energy and dispersion quality in ESBR as a function of heat treatment of N234. 

These materials are crystalline solids with high melting points which result in their poor dispersing qualities. Their addition also results in reduction of the cure state and lowering of compound modulus. 

Figure 9.12 Dispersion quality of carbon black as a function of residence time and applied shear...

Early antisealants used sodium hexametaphosphate (SHMP) as a threshold agent to inhibit the growth of calcium carbonate and sulfate-based scales.6 Most antisealants on the market today contain sulfonate, phosphate, or carboxylic acid functional groups. Perhaps the most effective antisealants today contain and blend of polyacrylic acid (PAA) and phosphoric acid or polyacrylate and a hydroyethylidene diphosphonate (HEDP).12 The polyacrylate-HEDP blends also claim to have good dispersion qualities toward silts and clays.12 Some new inhibitors include a chelant and disper-ant to keep suspended solids such as iron and manganese oxides in solution. These newer antisealants are generally more effective than SHMP for a variety of potential scales.6... 

Optical microscopy can be used to assess the dispersion quality of the nanotubes during the different steps of the composite processing. Figure 12.4 shows a uniform distribution of particles on macroscopic and microscopic scales after adding an isopropyl suspension of MWNTs to a solution of natural rubber (NR). Considering the resolution limit of optical microscopy, we deduce the absence of aggregates larger than one micrometer. 

The aim of this chapter is to provide an understanding of how carbon black particle size and shape translate into dispersion quality and other performance attributes in plastics applications. While this chapter focuses on carbon black s effectiveness as a pigment, some attention will also be paid to some of the other plastics performance properties it influences, such as stability against UV radiation, effects on mechanical properties, and electrical conductivity. At its conclusion, this chapter will help the reader select an appropriate carbon black grade for specific plastics applications. 

As mentioned earlier, dispersion quality also plays a strong influence on color. If carbon black is not completely dispersed, in a lOOx magnification light micrograph,... 

Figure 22.5. Schematic representation of a pressure rise test for dispersion quality.

TERRA AMPELITUS — A kind of Resinous Earth, found at Seleucia in Syria, and very similar to Bitumen. Pliny (1. 35, c. 16) tells us that it was the custom to cover vines with it for the destruction of vermin, and hence its name. It has affinity with coal, and uniform brilliance, is dissolved by oil, and has a cooling and dispersing quality in medicine. The black is commended by Pliny and Dioscorides, who disparage the grey and white varieties, which do not dissolve in moisture. It is called by the Germans Black Chalk. 

Figure 18.16 shows that carbon black incorporation time, BIT, is affected by the addition of ZnO and by the properties of carbon black. If no ZnO is added, the incorporation time decreases as the carbon black structure increases. The opposite is true when ZnO is present during carbon black dispersion. The overall quality of the dispersion improves when ZnO is present and when mixing is carried out at elevated temperature Dispersion quality was assessed by optical measurements. 

Our research hypothesis—which at that time lacked a sound theoretical foundation—that we should first make ICPs dispersible and then arrive at and optimise a conductivity jump by means of ever better dispersion (quality of raw material and new dispersion techniques), has so far stood the test (continuously published [4,17] and references cites therein and later) (Figure 11.11). This integrated materials-science-oriented work has made what are, from today s standpoint, invaluable contributions both to basic research and to applications research ... 

Several duties involving the dispersion of fine solids and emulsification cannot be carried out in the conventional mechanically agitated vessel because it is not possible to generate sufficiently high stresses to break>down the aggregated particles to achieve the required dispersion quality or to create a stable emulsion. 

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