Carbon black morphology effect

Carbon Black Morphology Effects on Abrasion Resistance.945... 

The effects of carbon black morphology on dispersibility described above have been borne out by practical experience. Higher surface area and lower-structure blacks are known to be more difficult to disperse. Traditionally, carbon blacks with surface areas higher than 160 m /g and CDBP lower than 60 mL/100 g cannot be sufficiently well dispersed using normal dry-mixing equipment, so they are not considered rubber grades. Figure 33.4 shows the ASTM carbon black spectrum used in the mbber industry, expressed by compressed DBPA versus surface area. 

M. C. Yu, J. Menashi, and D. J. Kaul, Carbon-Black Morphology Its Effect on Viscosity and Performance, Plastics Compounding, November/December, 1994. 

Table 9. Effect of Carbon Black Morphologies on the Properties of Filled Compounds...

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. 

DISPERSION OF CARBON BLACK IN ELASTOMERS 33.2.1 Effect of Morphology on Dispersibility of Carbon Black... 

Composite-based PTC thermistors are potentially more economical. These devices are based on a combination of a conductor in a semicrystalline polymer—for example, carbon black in polyethylene. Other fillers include copper, iron, and silver. Important filler parameters in addition to conductivity include particle size, distribution, morphology, surface energy, oxidation state, and thermal expansion coefficient. Important polymer matrix characteristics in addition to conductivity include the glass transition temperature, Tg, and thermal expansion coefficient. Interfacial effects are extremely important in these materials and can influence the ultimate electrical properties of the composite. 

In the literature, there are several reports that examine the role of conventional fillers like carbon black on the autohesive tack (uncured adhesion between a similar pair of elastomers) [225]. It has been shown that the incorporation of carbon black at very high concentration (>30 phr) can increase the autohesive tack of natural and butyl rubber [225]. Very recently, for the first time, Kumar et al. [164] reported the effect of NA nanoclay (at relatively very low concentration) on the autohesive tack of BIMS rubber by a 180° peel test. XRD and AFM show intercalated morphology of nanoclay in the BIMS rubber matrix. However, the autohesive tack strength dramatically increases with nanoclay concentration up to 8 phr, beyond which it apparently reaches a plateau at 16 phr of nanoclay concentration (see Fig. 36). For example, the tack strength of 16 phr of nanoclay-loaded sample is nearly 158% higher than the tack strength of neat BIMS rubber. The force versus, distance curves from the peel tests for selected samples are shown in Fig. 37. 

Both of these effects refer to a high surface activity and specific surface of the filler particles [26, 27, 47]. In view of a deeper understanding of such structure-property relationships of filled rubbers it is useful to consider the morphological and energetic surface structure of carbon black particles as well as the primary and secondary aggregate structure in rubber more closely-... 

The blend morphology containing conductive filler (e.g., carbon black) was simulated by the model based on Cahn s approach. Figure 16.10 shows the two-dimensional cut explaining the localization of carbon black between two incompatible phases, and Figure 16.11 shows the effect of carbon black concentration on the prediction of conductivity. This simple model of interfacial film partitioning... 

Figure 8. Relationship of morphology to the effectiveness of carbon black as a...

The quantitative aspects of the flow of carbon filled polymer compositions are extremely complex. Not only do the primary structure aggregates possess a complex morphology, but secondary aggregation leads to thixotropic effects, while surface chemical interactions modify the medium. The flow of typical rubber-carbon black mixes is invariably non-Newtonian. 

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