Particle geometry carbon blacks

The dispersion of agglomerates is strongly dependent on mixing time, rotor speed, temperature, and rotor blade geometry [3], Figure 3.28 [6,4] shows the fraction of undispersed carbon black as a function of time in a Banbury mixer at 77 rpm and 100°C. The broken line in the figure represents the fraction of particles smaller than 500 nm. 

The developments at Fraunhofer ICT focus on the combination of graphites and carbon black with different particle geometry and size distribution, to obtain as many contacts as possible between the conductive fillers, and thus produce conductive paths. The polymer serves in the material mixture as a binder to achieve a mechanically stable gas-tight system and to make a thermoplastic processing of the material compounds possible (Fig. 10). 

Generally, at least one critical dimension of dispersed particles in nanocomposites must be in the nanometer range (<100nm). Typical nanomaterials, which are currently under investigation, are classified by their geometries. Silica nanoparticles and carbon black are examples of nanoparticles, while carbon nanotubes and nanofibers are classified as fibrous nanomaterials. Silicate layers with platelike structure belong to the family of layered nanomaterials [4]. 

FIGURE 634 Geometry of a horizontal cylinder-mixer. Initially (r = 0) all carbon black particles are at the bottom of the cylinder that then is tnmbled horizontally and starts rotating. 

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