(46b) Dispersibility of Carbon Black As Function of Dispersing Intensity Using Hansen Dispersibility Parameters – Evaluation of Nonideal Mixing Effects Based on Normalized Relative Sedimentation Time
The paper intends to investigate this complexity for dispersibility of carbon black with the focus on effect of the dispersion process. HDP were determined based on experimental sedimentation behavior by means of automatically monitoring the integral extinction (IE) over sample height by STEP-Technology  for carbon black dispersed in different individual liquids of the 3D-Hansen space (chemical mapping). A modified relative sedimentation (standard) time (RST) taking into account acceleration and optical path was introduced . Higher RST values indicate higher dispersibility. Obviously RST values will be affected in case of fast agglomeration when particles are not properly stabilized by the solvent. Degree of dispersion processing intensity was varied between simple vortex mixing and sonication with varied input of energy. As predicted, best liquid(s) and HDP exhibit remarkable dependence on dispersion intensity. H-bond contribution reduces markedly in case of sonication with highest intensity. Noteworthy, liquids with H-bond acceptor properties proved to be especially effective in dispersion and dispersion stabilization.
To investigate and quantify nonideality for dispersion in binary liquid mixtures (experiments with low mixing intensity) it proved convenient to directly use RST values determined as function of mixing ratio. Synergistic and antagonistic effects were clearly identified and dispersibility improved.
The authors want to thank the funding of Deutsche Forschungsgemeinschaft (DFG) through the Cluster of Excellence âEngineering of Advanced Materialsâ. Moreover, we acknowledge the Federal Ministry of Economic Affairs through the Arbeitsgemeinschaft industrieller Forschungsvereinigungen âOtto von Guerickeâ e.V. (AiF, project no. KF 2347922UW4).
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