However, a similar study by Sis and Birinci indicated that the NPE with 10 moles of EO per surfactant molecule showed the best performance.
Gupta and Bhagwat observed an increase in carbon black colloidal stability with an increase in number of EO groups in the NPE surfactant. In the case of non-ionic surfactants belonging to nonylphenol ethoxylates (NPE) class, the hydrophobic nonylphenol groups adsorb strongly on the surface of carbon black, while the steric stabilization is provided by hydrophilic ethylene oxide (EO) groups. The colloidal stability of the carbon black particles in presence of CTAB has been attributed to the monolayer adsorption of CTAB, which provides stability against aggregation through a combination of electrostatic repulsion and steric hindrance. Ĭationic surfactants like cetyltrimethylammonium bromide (CTAB) and cetyltrimethylammonium chloride (CTAC) have been found to efficiently disperse carbon black particles. Several dispersants have been used for dispersing carbon black including cationic surfactants, anionic surfactants, and non-ionic surfactants. Dispersions with low carbon black loadings can be achieved by mixing carbon black particles in water under high shear conditions, but preparation of dispersions with high carbon black loading (≥ 20 wt%) requires the use of a dispersant to prevent excessive viscosity build-up. Carbon blacks do consist of oxygen containing groups like carbonyl, carboxyl, pyrone, phenol, quinone, lactone, and ether groups bound to their surface. However, carbon blacks are inherently hydrophobic due to their high elemental carbon content, typically greater than 95%, and have a low wettability, thereby making it difficult to disperse them in aqueous medium. Īn aqueous dispersion of carbon black is generally a requirement to prepare printing ink and latex masterbatches. In order to make it easier to handle, carbon black is typically sold in the form of pellets. The primary particle size of carbon black is typically around 10 nm, but they tend to aggregate via covalent bonding, followed by formation of larger agglomerates (microns size) due to Van der Waals forces. Carbon blacks are characterized by their particle size, structure, and surface chemistry, and these three properties determine the dispersibility of carbon black. About 90% of the carbon black produced worldwide is used in rubber industry, while the remaining 10% is utilized in non-rubber industries including printing inks, plastics, and coatings. Carbon black refers to the commercial form of solid carbon produced by thermal decomposition or thermal combustion of hydrocarbons.
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