Carbon black shape factor

The furnace process involves injecting low end fraction of cmde oil, eg. Bunker Euel C, into a heated chamber. The temperature, shape of the injectors of the oil, rate of injection, and other factors are controlled to produce black fillers of different particle si2e and stmcture. The particle si2e and stmcture control the reinforcing character of the carbon black. There are 30 common grades of carbon black used in the mbber industry. There are numerous specialty grades produced, and several hundred are used in plastic, conductive appHcations, and other uses. 

Since carbon black and amorphous silica tend to form clusters of spheres (grasping effect), an additional modification of the Einstein equation was made to account for the nonspherical shape or aspect ratio (L/D). This factor (/) is equal to the ratio of length (L) to diameter (D) of the nonspherical particles (/= L/D). 

Particle Shape. Shape Factors. The method of formation plays a major role in shaping the resultant particles. Particles generated by comminution, attrition, or disintegration resemble the parent material. However, if the method of formation is condensation from vapor or precipitation from solution, the smallest unitary particle may be spherical or cubical. Often condensation is followed immediately by solidification and the formation of chainlike aggregates (e.g., iron oxide fumes, carbon black). In liquid suspensions, similar particle aggregation or flocculation is important in determining suspension behavior. 

Co-extrusion processing using thermoplastic binder systems for ceramic bodies has been described by Van Hoy [Hoy 98]. The major binder component used in this study was ethylene vinyl acetate, and methoxypoly-ethylene glycol was used as a plasticizer. Feedstocks of alumina, a piezoelectric ceramic powder and carbon black were repeatedly co-extruded to form an array of fine M -shaped structures. With this method the size of the alumina M shapes could be reduced by a factor of 915. In this example the use of solvent-based binders would have been problematical because of drying of the feedstocks and extrudates during the co-extrusion process and during handling. 

All carbon blacks are semicondnctive, bnt certain grades are preferred where composite conductivity is desired. The degree of effectiveness is determined by four factors particle size, structure (shape), porosity, and surface chemistry. 

New kaolins give excellent tensile and tear strength, and abrasion resistance in general purpose compounds where colour is not a critical factor. They also offer the processability and particle shape advantages of kaolin, and can be used as a partial replacement for carbon black, where they give good cost effectiveness. 

Particle formation is very similar to that for carbon black, with very small, primary particles forming first and then fusing, while still mobile, into chain-like aggregates. Properties like particle size, surface area and shape are controlled by factors such as reactant ratio, temperature and turbulence. Because of the high temperature formation process, the surface is less hydroxylated than that of the precipitated silicas, and as a result adsorbs less water. The moisture loss at 105 °C is usually less than 1.5%. 

The nature of the carbon used as an electronic conductor may vary carbon black from different sources with particle size distributions (PSDs) of 30-40 nm and specific surface areas of 100-2,000 mVg (BET surface), activated carbons, carbon fibers or indeed carbon nanotubes (CNTs). The type of carbon, its morphology and its mode of dispersion or coating play a part in the resulting electrical properties of the electrode. For instance, carbon fibers or CNTs improve the electronic conductivity of thick electrodes, because their high shape factor enables them to form a good electronic percolation lattice.In the presence of CNTs, a capacity of 900 mAh/gs in the first cycle and 75% retention of capacity after 60 cycles (with a charge/discharge current density of 100 mA/g and 68% sulfur in the... 

The polymer-carbon black filler reinforcement depends widely on the polymer type, carbon black type and structure. Another factor affecting this reinforcement is the filler-filler interaction which leads to the formatimi of three dimensional aggregation structures within the bulk of the rubber matrix. Figure 12 shows the aggregation and agglomeration of carbon black in the rubber. These aggregations takes various shapes which may be spherical or ellipsoidal with different major and minor... 

Medalia, A.I. and Heckman, F.A. (1969) Morphology of aggregates - II. Size and shape factors of carbon black aggregates from electron microscopy. Carbon, 7, 567. 

---