Ultra-fine carbon

Kozawa et al. proposed the use of ultra-fine carbon (UFC) and polyvinyl alcohol (PVA) composite colloid as additive to electrolyte [46]. They demonstrated that UFC—PVA colloid converts inactive PbS04 accumulated in the negative electrode into an active one and improves its solubility. These effects are due to the influence of UFC colloid to reduce the size of PbS04 crystallites produced on discharge. The UFC—PVA colloid solution comprises carbon black particles 0.15 mm in size and PVA in a ratio of 10 4 by weight. Addition of 5 vol% of UFC—PVA colloid to the cell electrolyte has been recommended, i.e., the amount of colloid solid carbon is about 0.25 g per 100 mL of electrolyte. The UFC—PVA colloid reduces the selfdischarge of negative plates and can act as an activator (de-passivator) of the sulfated lead electrode. 

Vapor-grown carbon fibers have been prepared by catalyzed carbonization of aromatic carbon species using ultra-fine metal particles, such as iron. The particles, with diameters less than 10 nm may be dispersed on a substrate (substrate method), or allowed to float in the reaction chamber (fluidized method). Both... 

Ground calcium carbonate, extracted from the earth, is present in practically every country in the world in varying quantities in the form of limestone, marble, dolomite or chalk. Following the extraction, GCC needs to be ground. Dry grinding, the cheaper alternative, is often limited to a minimum particle size of 2- 3 microns. Wet grinding, more expensive, is used for fine and ultra fine material or when the final product must be a slurry (paper or paint application). Precipitated calcium carbonate is produced by chemical reaction between... 

These specific requirements of a calcium carbonate slurry used for paper coating have necessitated the development of new dispersants that allow the preparation of ultra fine calcium carbonate slurries at high solids concentration that provide good rheological behaviour in coating. 

This article studies some of the polymer characteristics influencing the slurry dispersion and describes a new class of acrylic based polymer showing promising dispersing properties for ultra fine calcium carbonate slurries. 

We developed another dispersant presenting properties for a special application. In some cases when an ultra fine calcium carbonate slurry is spray dried, a re-agglomeration of the powder often occurs, due to high water adsorption. This powder aggregation is detrimental to the quality of the final product. 

Aluminium and magnesium hydroxides are difficult to produce directly in any useable form from their natural ores. Filler grade calcium carbonate is widely produced from natural sources, but grinding costs appear to become prohibitive when ultra-fine particles are required and precipitation procedures then become competitive. Further details of precipitation procedures will be found under the specific filler types. 

The milk of lime should be grit-free and should have as high a surface area as is practicable. Traditionally this has been produced by slaking a low carbonate quicklime under conditions favouring the production of finely divided calcium hydroxide (see chapter 22). More recently, ultra-fine milks of lime (see section 22.8) have proved to be particularly effective lubricant carriers. 

Filler - Ultra-Fine Precipitated Calcium Carbonate ... 

NOTE To obtain plasticizer control data, see Table III (50 pph Ultra Fine Precipitated Calcium Carbonate) for PbO MnO cures respectively. 

Y Takasu, W. Sugimoto, and Y Murakami, Electrocatalytic oxidation of methanol and related chemical species on ultra fine Pt and Pt-Ru particles supported on carbon. Catalysis Surveys from Asia, 7(1) (2003) 21-29. 

Thus Nicolon (Nippon Carbon, Japan) is reported to be homogeneously composed of ultra-fine beta-SiC crystallites and an amorphous mixture of silicon, carbon, and oxygen. The fibre is available as continuous filament, chopped fibre, woven cloth (three weaves available), and nonwoven felt each having 14 pm diameter fibres/fila-ments present. 

Figure 8.18 TEM photographs of fibers showing tip and hollow tube. Source Reprinted with permission from Endo M, Katoh A, Sugiura T, Shiraishi M, High resoiution eiectron microscopy of vapour grown carbon fibres obtained by ultra-fine fluid catalyst, Extended Abstracts of the 18th Biennial Conference on Carbon, Worcester, MA, (American Carbon Society), 151-152, 1987. Copyright 1987, The American Carbon Society.

Both the ground and precipitated calcium carbonates can by treated with stearic acid to control water absorption, improve dispersabUity, and promote better wetting of the flUer by rubber. Silane treatment of these fillers is not effective. However, there is an ultra-fine grade coated with carboxylated polybutadiene, which reactively links to the particle surfaces. Such treated ultra-fine products can give reinforcement of about the same level of the semireinforcing thermal carbon blacks. 

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