Evaluating the Rheo-electric Performance of Aqueous Suspensions of Oxidized Carbon Black

Paolo Zapanta Ramos, Connor Clayton Call, Lauren Virginia Simitz, Jeffrey John Richards*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Hypothesis: The macroscopic properties of carbon black suspensions are primarily determined by the agglomerate microstructure built of primary aggregates. Conferring colloidal stability in aqueous carbon black suspensions should thus have a drastic impact on their viscosity and conductivity. Experiments: Carbon black was treated with strong acids following a wet oxidation procedure. An analysis of the resulting particle surface chemistry and electrophoretic mobility was performed in evaluating colloidal stability. Changes in suspension microstructure due to oxidation were observed using small-angle X-ray scattering. Utilizing rheo-electric measurements, the evolution of the viscosity and conductivity of the carbon black suspensions as a function of shear rate and carbon content was thoroughly studied. Findings: The carboxyl groups installed on the carbon black surface through oxidation increased the surface charge density and enhanced repulsive interactions. Electrostatic stability inhibited the formation of the large-scale agglomerates in favor of the stable primary aggregates in suspension. While shear thinning, suspension conductivities were found to be weakly dependent on the shear intensity regardless of the carbon content. Most importantly, aqueous carbon black suspensions formulated from electrostatically repulsive primary aggregates displayed a smaller rise in conductivity with carbon content compared to those formulated from attractive agglomerates.

Original languageEnglish (US)
Pages (from-to)379-387
Number of pages9
JournalJournal of Colloid And Interface Science
StatePublished - Mar 15 2023


  • Carbon black
  • Colloidal stability
  • Conductive additive
  • Flow electrode
  • Rheo-electric characterization
  • Surface oxidation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Biomaterials
  • Colloid and Surface Chemistry


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