Characterization and stabilization of nano-metakaolin colloidal suspensions
2021
Malta, Juliana O. | Oliveira, Lucas V.S. | Ueki, Marcelo M. | Barreto, Ledjane S.
Nanometric powders bear significant problems in the efficiency of dispersion. The ideal situation would be to ensure full nanoparticle separation in suspensions or composites matrix, which is hard to achieve due to the high reactivity and aggregation. This study evaluates the conditions to stabilize nano-metakaolin (NMK) in water suspension by analyzing the influence of solute concentration, pH, type and content of dispersants. Potentiometric titration curves, zeta potential and average particle size measurements were performed, along with rheological measurements, at different times: 0 h, 3 h, 6 h and 24 h. NMK particles showed the same tendency of surface charge distribution, regardless of solute concentration. The dispersed NMK particles presented two isoelectric points, attributed to the multiple arrangements they form when in suspension. Polycarboxylate (PC) was the dispersant that provided greater dispersion stability. Regarding the rheological and zeta potential measurements, the suspensions presented stability up to 24 h.
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