Coating precipitation

Table 4. Effect of measuring conditions on the apparent particle size of a coated precipitated calcium carbonate (Reprinted from [3] with permission of Addison Wesley Longman Ltd)...

Adsorption of mercury. All chemicals used were Merck or Baker analytical quality reagents, unless stated otherwise. From the commercially available adsorbents the following were used silica gel 60 A porosity, 0.063-0.200 mm particle size (Merck) charcoal 0.3-0.5 mm particle size, gas-chromatographic quality (Merck) alumina R Woelm hydrous zirconium oxide HZ0-1, 100-200 mesh, (Bio-Rad). Except for zirconium phosphate, which was prepared according to Amphlett ( ), all other sorbents were prepared by coating (precipitation) on acid-purified silica gel, as described in (1 ). The Si0 -NH was prepared according to Leyden et al (11). L... 

The primary particle size of Winnofil stearate coated precipitated calcium carbonate from Zeneca Resins is in the region of 0.075 micron. When compounded into natural and synthetic elastomers, the hydrophobic surface coating assists wetting and aids dispersion. When compounded into plasticised PVC for cable sheathing, the PCC allows for formulations with minimal potential for acid gas release in combustion conditions. In rigid PVC, stearate coated PCC has been used in compounding as an alternative to conventional acrylic processing aids and as a means to reduce impact modifier levels. 

For the preceding coating precipitation, what is initially Ihe diffii-sion controlled growth rate of the particles if the initial saturation... 

Columns for LLPC are prepared by using solvent evaporation, direct coating, precipitation, or a dynamic coating technique [3], In the solvent-evaporation technique, the nonvolatile hquid stationary phase is dissolved in a volatile solvent and mixed with the dry sup-... 

Use of fine particle size precipitated carbonate filler provides good reinforcing properties and also increases viscosity. Some fine particle size precipitated carbonates are coated with stearic acid to improve wetting. These fillers are desirable where a high pH is required in a compound. Fine particle size coated precipitated carbonates improve thixotropy of a compound. 

Phosphate conversion coating precipitates on the cathodic site at a pH range of 6-8, while pinholes are formed on the anodic sites. Because the phosphate conversion film is not uniformly deposited on the surface, it does not provide a good barrier protection. 

Stearic acid coated, precipitated calcium carbonate 0.1... 

Figure 4.2 Use of the dye adsorption technique to follow the effect of ultrasonic treatment on the amount of bare surface in both uncoated and coated precipitated calcium carbonates (congo red dye adsorbed from aqueous solution)...

Table 4.4 A comparison of a rosin and a fatty add coated precipitated calcium carbonate in a sulfur cured styrene-butadiene rubber (SBR) elastomer (100 phr filler) ...

Flexible PVC compounds often contain 10-50 phr of fillers, normally calcium carbonate, which can be simply ground chalk or stearate coated precipitated calcium carbonate of finely controlled particle size. Examples are cable sheathing, footwear compounds and general extrusions. Other PVC compounds of a more specialised nature such as flooring compositions may contain from 100-500 phr of filler, often mixtures of calcium carbonate and asbestos flour. In this case the PVC compound is merely acting as a binder to hold the filler particles together. Electrical insulation... 

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