title: Aggregation kinetics and gel formation in modestly concentrated suspensions of oppositely charged model ceramic colloids: a numerical study.
abstract: Aggregation kinetics and gel formation in aqueous suspensions that undergo heteroaggregation are studied by means of Brownian dynamics simulations. The simulated system, described in a previous paper [M. A. Piechowiak, A. Videcoq, F. Rossignol, C. Pagnoux, C. Carrion, M. Cerbelaud, R. Ferrando, Langmuir, 2010, 26(15), 12540-12547.], is constituted of two kinds of synthesized, almost equally sized colloids: silica particles that are negatively charged and alumina-coated silica particles that are positively charged. The interactions between colloids are modeled by the DLVO potential. Several compositions are analyzed, from silica-rich to alumina-rich cases. The particle volume fraction φ is varied in the range 6-12%. The study of the aggregation kinetics allows us to clarify the effect of those variations on the clustering process. Gelation is analyzed by detection of spanning clusters in each x-, y-, z-direction of the cubic simulation box. Percolating networks start to be observed from φ = 7%, a low value of the volume fraction close to the solid volume fraction experimentally measured in sediments of those suspensions.
authors.affiliation: SPCTS, UMR 6638, ENSCI, CNRS, Centre Européen de la Céramique, Limoges, France.
authors.forename: M A
authors.initials: MA
authors.lastname: Piechowiak
authors.forename: A
authors.initials: A
authors.lastname: Videcoq
authors.forename: R
authors.initials: R
authors.lastname: Ferrando
authors.forename: D
authors.initials: D
authors.lastname: Bochicchio
authors.forename: C
authors.initials: C
authors.lastname: Pagnoux
authors.forename: F
authors.initials: F
authors.lastname: Rossignol