title: Effect of water on overbased sulfonate engine oil additives.
abstract: The presence and effect of water on calcium carbonate nanoparticles used in engine additives, stabilized with a sulfonate surfactant, is investigated using small-angle neutron scattering, dynamic light scattering, Fourier transform infrared spectroscopy, and rheometry. These techniques provide complementary data that suggests the formation of a layer of water around the core of the particles ensuring continued colloidal stability yet increasing the dispersion viscosity. Through the use of small-angle neutron scattering, the dimensions of this layer have been quantified to effectively one or two water molecules in thickness. The lack of a significant electrostatic repulsion is evidence that the water layer is insufficient to cause major dissociation of surface ions.
authors.affiliation: Department of Chemical and Process Engineering, University of Sheffield, Mappin Street, Sheffield, United Kingdom.
authors.forename: J W
authors.initials: JW
authors.lastname: Tavacoli
authors.forename: P J
authors.initials: PJ
authors.lastname: Dowding
authors.forename: D C
authors.initials: DC
authors.lastname: Steytler
authors.forename: D J
authors.initials: DJ
authors.lastname: Barnes
authors.forename: A F
authors.initials: AF
authors.lastname: Routh
mesh_terms: D007219:Industrial Oils; D013055:Spectrophotometry, Infrared; D013450:Sulfones / Q000737:chemistry*; D014783:Viscosity / Q000187:drug effects; D014867:Water / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D013450:Sulfones; D014867:Water