Carbon black, determination

Figure 15.34. Bound rubber vs. oxygen content in carbon black determined for NBR compositions. [Data from Bandyopadhyay S, De P P, Tripathy D K, De S K, J. Appl. Polym. Sci., 58, No.4, 1995, 719-27.]...

Figure 7.2 The three characteristics of carbon black determining its rich properties particle...

Quantity of residual amount of stabilizers adsorbed on carbon black determined by UVA TC, and EMC analyses... 

Homogeneously distributed, fine-grained carbon black proved an effective and cost-efficient stabiliser against UV radiation. It is either added to the polyethylene by the raw material manufacturer or during geomembrane production. Properties, content and homogeneity of the distribution of carbon black determine the quality of UV stabilisation. 

Figure 15.34. Bound rubber vs. oxygen content in carbon black determined for NBR compositions. [Data from...

Carbon-black types are differentiated on particle size and surface area measurements, using techniques such as TEM, PCS (photon correlation spectroscopy), iodine or nitrogen adsorption and mercury porosimetry. The best method for qualitative carbon-black determination is based on accurate measurement of the CB particle size using TEM [222,223], Pyrolysis at 800 to 900 C followed by TEM analysis according to ASTM D 1765 allows identifying carbon-blacks used in rubber products [224]. TEM was used for identiflca-tion of carbon-blacks in vulcanisates [225], TGA has been used for quantitative determination of carbon-black [226,227]. Palla [51] used TEM for the characterisation of rubber components. Ultra-thin sections of rubbers suitable for TEM studies can be prepared by microtoming at low temperatures. 

These effects can be illustrated more quantitatively. The drop in the magnitude of the potential of mica with increasing salt is illustrated in Fig. V-7 here yp is reduced in the immobile layer by ion adsorption and specific ion effects are evident. In Fig. V-8, the pH is potential determining and alters the electrophoretic mobility. Carbon blacks are industrially important materials having various acid-base surface impurities depending on their source and heat treatment. 

There are complexities. The wetting of carbon blacks is very dependent on the degree of surface oxidation Healey et al. [19] found that q mm in water varied with the fraction of hydrophilic sites as determined by water adsorption isotherms. In the case of oxides such as Ti02 and Si02, can vary considerably with pretreatment and with the specific surface area [17, 20, 21]. Morimoto and co-workers report a considerable variation in q mm of ZnO with the degree of heat treatment (see Ref. 22). 

Fig. XVn-21. (a) Differential heat of adsorption of N2 on Graphon, except for Oand , which were determined calorimetrically. (From Ref. 89.) (b) Differential heat of adsorption of N2 on carbon black (Spheron 6) at 78.5 K (From Ref. 124).

Commercially produced elastic materials have a number of additives. Fillers, such as carbon black, increase tensile strength and elasticity by forming weak cross links between chains. This also makes a material stilfer and increases toughness. Plasticizers may be added to soften the material. Determining the effect of additives is generally done experimentally, although mesoscale methods have the potential to simulate this. 

Fig. 2.13 Adsorption of nitrogen on a carbon black before graphitiz-ation. - The difTerential heat of adsorption Ji, plotted against n/n , was determined calorimetrically at 78 K (O, , A) and was also calculated from the isotherms at 78 6 and 90-1 K (+ ). (Courtesy Joyner and Emmett.)...

Specific surface area of carbon blacks before and after graphitization, determined by electron microscopy (A,) end by nitrogen adsorption (A ]t... 

Molecular area, a (Ar) of argon at 77 K on graphitized carbon blacks (Argon BET plots constructed with p (liquid) surface areas determined by BET-nitrogen, with a (Na)... 

Acid-Base Behavior. The relative acidity-basicity of the filler, generally determined by measuring the pH value of a slurry of a specific mass of filler in 100 mL of deionized water, can influence the behavior of a filler in some systems. For example, the curing behavior of some elastomers is sensitive to the pH value of carbon black. 

The ash content of furnace blacks is normally a few tenths of a percent but in some products may be as high as one percent. The chief sources of ash are the water used to quench the hot black from the reactors during manufacture and for wet pelletizing the black. The hardness of the water, and the amount used determines the ash content of the products. The ash consists principally of the salts and oxides of calcium, magnesium, and sodium and accounts for the basic pH (8—10) commonly found in furnace blacks. In some products potassium, in small amounts, is present in the ash content. Potassium salts are used in most carbon black manufacture to control stmcture and mbber vulcanizate modulus (22). The basic mineral salts and oxides have a slight accelerating effect on the vulcanization reaction in mbber. 

In this article, we will discuss the use of physical adsorption to determine the total surface areas of finely divided powders or solids, e.g., clay, carbon black, silica, inorganic pigments, polymers, alumina, and so forth. The use of chemisorption is confined to the measurements of metal surface areas of finely divided metals, such as powders, evaporated metal films, and those found in supported metal catalysts. 

As far as conducting fillers are concerned, we have rather a wide range of choice. In addition to the traditional and long used fillers, such as carbon black and metal powders [13] fiber and flaky fillers on organic or metal bases, conducting textures, etc recently appeared and came into use. The shape of the filler particles varies widely, but only the particle aspect ratio, the main parameter which determines the probability... 

The effect of synthesis gas composition on conversion, catalyst life, carbon black formation, etc. was determined in numerous tests. Characteristic variables in the synthesis gas composition are the H2/CO ratio, residual C02 content, and content of trace components in the form of higher hydrocarbons and catalyst poisons. 

The morphology of the agglomerates has been problematic, although some forms of network-like structures have been assumed on the basis of percolation behavior of conductivity and some mechanical properties, e.g., the Payne effect. These network stmctures are assumed to be determining the electrical and mechanical properties of the carbon-black-filled vulcanizates. In tire industries also, it plays an important role for the macroscopic properties of soft nano-composites, e.g., tear. 

The morphology of the carbon was characterized by SEM and the particle size was determined by particle size analyzer. Figure 4 shows the SEM images of the carbon black. It was observed that the carbon black particles exhibit a sphere particle with nano-sized diameter. 

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