Elucidating the particle concentration-dependent flow behavior of aqueous TiO2 suspensions based on polymer dispersant structures and interparticle surface distances

• Published in: Powder technology 2023-06, Vol.423, p.118473, Article 118473
• Main Authors: Ito, Fumiya, Honda, Takuya, Komuro, Haruka, Yoshikawa, Fumitaka, Tatami, Junichi, Iijima, Motoyuki
• Format: Article
• Language: English
• Subjects: Adlayer thickness; dispersants; Flow curve; hysteresis; nanoparticles; polyethylene; Polymer dispersant; Surface distance; Suspension stability; titanium dioxide; van der Waals forces; viscosity
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2023.118473

Flowing behavior of concentrated aqueous TiO2 suspensions was evaluated in relation to the structure of polymeric dispersants, their adlayer thickness on particle surface, and particle concentrations. Comb-type polymeric dispersants comprising polyethylene glycol-based side chains with different combinations of unit number and side chain length were investigated. Based on particle concentration–apparent viscosity curves of the suspensions with TiO2 nanoparticles saturated with dispersants, maximum packing fraction and polymer adlayer thickness were estimated through the Krieger–Dougherty model. When the steric repulsive force of polymer dispersant dominated van der Waals attractive forces, the flow curves of the suspension exhibited hysteresis characteristics as the average particle surface distance approached the adlayer thickness of polymer dispersants. Additionally, by introducing the concept of relative surface distance, which is the average particle surface distance divided by the adlayer thickness, the particle concentration dependency of the suspension viscosities with different dispersants followed a unified trend. [Display omitted] •Flow behavior of aqueous TiO2 suspensions was systematically evaluated.•Comb-type polymer dispersant structures and particle concentration was focused.•Polymer adlayer thickness was estimated by the Krieger–Dougherty model.•Particle surface distance was divided by adlayer thickness for new parameter.•The new parameter unified the particle concentration–apparent viscosity profiles.