Surface analyses, carbon blacks

Most of these elements are concentrated on the surface of the carbon black. Removal of traces of organic elements is possible with the use of special solvents. The carbon black extraction based on toluene, the toluene extract, results in values of mostly less than 0.1%. Further analysis of the material shows, among other substances, minute quantities of PAHs (polycyclic aromatic hydrocarbons), which are tightly bound to the carbon black surface. 

Even if they are usually called primary particles, spheres that constitute aggregate are partially fused together and never exist by themselves. Anyway, their size is of great importance because it defines the actual surface of interaction between carbon black and elastomeric phase the lower the size of primary particles, the higher the interface extension. Primary particle size distribution has been estimated by TEM image analysis, but carbon black surface area is usually more efficiently obtained by adsorption methods (see later section on surface area). 

Analysis of dry carbon black surface indicated the presence of a range of hydrocarbon groups, which is in line with earlier work (LeBras and Papirer, 1979). These groups are capable of reacting with other functional groups. 

Often the amount of carbon black (CB) in a sample can be determined by switching the gas in the TGA from nitrogen to air or oxygen at 500 0 to 550 C such that CB converts to CO2. The carbon-black surface area can be approximated from the temperature of its decomposition, often taken as T15 or T20, the temperature at which 15% or 20% of combustion is complete [see Mauer (1981) Sircar (1997) and Rg. 3.20]. This CB analysis assumes all polymeric material has been volatilized prior to the introduction of oxygen. Beware of polymers that can form a char, such as those that contain aromatic structures, for they can cause erroneous CB determinations unless the pyrolysis of their... 

The analysis is thus relatively exact for heterogeneous surfaces and is especially valuable for analyzing changes in an adsorbent following one or another treatment. An example is shown in Fig. XVII-24 [160]. This type of application has also been made to carbon blacks and silica-alumina catalysts [106a]. House and Jaycock [161] compared the Ross-Olivier [55] and Adamson-Ling... 

Od-fumace blacks used by the mbber iadustry contain over 97% elemental carbon. Thermal and acetylene black consist of over 99% carbon. The ultimate analysis of mbber-grade blacks is shown ia Table 2. The elements other than carbon ia furnace black are hydrogen, oxygen, and sulfur, and there are mineral oxides and salts and traces of adsorbed hydrocarbons. The oxygen content is located on the surface of the aggregates as C O complexes. The... 

Table 2.7 lists techniques used to characterise carbon-blacks. Analysis of CB in rubber vulcanisates requires recovery of CB by digestion of the matrix followed by filtration, or by nonoxidative pyrolysis. Dispersion of CB within rubber products is usually assessed by the Cabot dispersion test, or by means of TEM. Kruse [46] has reviewed rubber microscopy, including the determination of the microstructure of CB in rubber compounds and vulcanisates and their qualitative and quantitative determination. Analysis of free CB features measurements of (i) particulate and aggregate size (SEM, TEM, XRD, AFM, STM) (ii) total surface area according to the BET method (ISO 4652), iodine adsorption (ISO 1304) or cetyltrimethylammonium bromide (CTAB) adsorption (ASTM D 3765) and (iii) external surface area, according to the dibutylphthalate (DBP) test (ASTM D 2414). TGA is an excellent technique for the quantification of CB in rubbers. However, it is very limited in being able to distinguish the different types of... 

Supported nanoparticles (1-1.5 nm) based on Ru4Pt2 entities have been obtained by using a Ru4Pt2(CO)i8 precursor on carbon black and fullerene soot [63]. XANES analysis showed differences between the interaction of nanoparticles with both carbon black and fullerene supports. In particular, a change in the electronic properties of the nanoparticles on fullerene is proposed this change was related to a strong interaction between the nanoparticle and a surface-atom, probably via the formation of a Ru-carbide phase. 

Ismail, l.M.K. Pfeifer, P. (1994) Fractal analysis and surface roughness of nonporous carbon fibers and carbon blacks. Langmuir 10 1532-1538... 

Carbon also is produced and used in other forms namely, activated carbon, carbon black, and coke, that have many commercial applications. Structurally they are amorphous forms of carbon belonging to the graphites. Activated carbon or activated charcoal has a highly porous honeycomb-like internal structure and adsorbs many gases, vapors, and colloidal solids over its very large internal surface area. Some of its major applications include purification of water and air, air analysis, waste treatment, removal of subur dioxide from stack gases, and decolorization of sugar. 

Sorption Analysis. Specific surface areas and porosity can be calculated from the adsorption isotherm of nitrogen at — 196 °C. The method of Brunauer, Emmett, and Teller [4.29] is generally accepted for the evaluation of specific surface areas (BET surface area in square meters per gram). The two-parameter equation is applicable to carbon black. The BET surface area comprises the outer surface area as well as the surface area of the pores. 

Kodama and co-workers [58] have reported TG-DSC curves for the analysis of the interaction between vulcanisation accelerators (tetramethylthiuram disulphide, dibenzothiazolyl disulphide, diphenylguanidine and N-cyclohexyl-2-benzothiazolyl-sulphenamide) and fillers (carbon black, white carbon, hard clay and CaC03). The initial melting point (MP) of the accelerators was largely influenced by the fillers. The higher the surface activity of the filler is, the lower and wider the melting range becomes. 

For the characterization of surface roughness of carbon blacks, different experimental techniques have been applied in the past. Beside microscopic investigations, e.g., AFM that give an impressive but more qualitative picture [90-92], scattering techniques such as SANS [93] and SAXS [94-96] as well as gas adsorption techniques [79-84, 97-99] have been used for a fractal analysis of surface roughness. The results discussed in the literature appear somewhat controversy, since almost flat surfaces with ds 2 [98, 99] and also rough surfaces with 2.2[Pg.12]

The carbon blacks consisted of Spheron 6 and Sterling FT (fine thermal) black, both non-heat-treated and 2700° C. heat-treated (obtained from the Godfrey L. Cabot Co., Boston, Mass.). Published surface areas for the four carbon blacks are 114, 84.1, 15.5, and 12.5 sq. meters per gram, respectively (31). The silica sand was supplied by the New Jersey Silica Sand Co., Millville, N. J., with the manufacturer s designation of No. 325 flour. Screen analysis by the supplier showed a considerable range in particle size about 60% was retained on a 90-mesh screen and 90% on a 200-mesh screen. Finally, a sample of asbestos was tested (obtained from the Canadian Johns-Manville Co., Port Credit, Toronto, with the designation 7R). Zettlemoyer (31) has studied this material. 

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