Browsing by Author "Hanley, HJM"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Adsorption of a jet fuel on a model organic-clay soil: application of small angle neutron scattering
    (National Research Council Canada, 2009-03-14) Hanley, HJM; Payne, TE
    Small angle neutron scattering (SANS) data are reported from a system that models the contamination of a clay/organic matter soil from a fuel spillage. The soil was represented as an aqueous dispersion of the synthetic clay mineral Laponite coated with lysine, and the contaminant was a representative jet fuel, quadricyclane, mixed with the detergent cetyltrimethylammonium bromide (CTAB). The adsorbed surface coverage on the clay was estimated. It is shown that the presence of adsorbed lysine considerably enhances the subsequent adsorption of both CTAB and quadricyclane. It is demonstrated that the SANS technique can contribute to the general problem of environmental remediation and retention by probing the interactions of pollutants and clay surfaces. © 2008, National Research Council Canada
  • Thumbnail Image
    Item
    Challenges of kinetic measurements with a Bonse-Hart neutron diffractometer
    (International Conference on Neutron Scattering, 2017-07-12) Garvey, CJ; de Campo, L; Rehm, C; Muzny, CD; Hanley, HJM
    Here we report on kinetic studies of the structural effects of applied shear on the gelation of silica using the Bonse-Hart type double crystal diffractometer (USANS) Kookaburra (ANSTO, Lucas Heights Australia). This instrument is able to cover a range of scattering vectors, 2.8 x 10-5 Å-1 < q < 4x 10-2 Å-1. The gelation process may be viewed structurally as the aggregation of sol particles into larger fractal aggregates, which then form a percolative network (final gel). In previous SANS work, it was shown that shear interrupted the formation of the network, inducing a new, shear dependent structure where there are structural changes on the micron length scale. Here we use USANS to understand the structural pathway that the gel follows to the steady shear state. USANS measurements are made point by point with each rotation step of the analyzer crystal (rocking curve), with counting statistics aimed at resolving a signal above the background. To gather a comprehensive rocking curve, a single measurement will take of the order of hours, putting the ability to cover interesting kinetics beyond the realm of an ordinary beamtime allocation. Here, USANS measurements were made on the gelling system, where each measurement consists of a restricted number of points in the rocking curve, with points selected according to their ability to characterize the intermediate structure.
  • Thumbnail Image
    Item
    Flow assurance in a model crude oil: a structural and rheometric study.
    (Australian Nuclear Science and Technology Organisation, 2008-04) Drabarek, E; Muzny, C; Bryant, G; Hanley, HJM
    This report investigates how the technique of small angle neutron scattering (SANS) helps elucidate the phenomenon of wax deposition in a petroleum crude oil. Specifically, we report SANS data, supplemented by results from dynamic light scattering (DLS), obtained from a synthetic petroleum crude oil: a mixture of commercial paraffin wax dissolved in an octane/cyclohexane solvent. The system is a gel below the cloud point. The onset and growth of this waxy gel, and changes in its nanostructure, are recorded here as a function of temperature over the range 10 ≤ T/°C ≤ 65. SANS indicates that the wax has a definite characteristic length of about 100 Å (10 nm) which can be observed at temperatures as high as 57°C, but DLS indicates that the wax also contains very large structures - of the order of a micrometer - over the temperature range 30° - 50°C. The structural studies are supplemented by corresponding sets of viscosity and stress data taken from the gelling wax when subjected to an applied shear. We observe that the stress will increase as the temperature falls - i.e. as the system gels - but, in general, will then reach a maximum and tend to decline. The wax results are compared with those from an equivalent system consisting of a major component of the wax: n-docosane, C22. Significant differences between the behavior of the wax and the pure component in the solvents are noted. The SANS patterns to 20°C from docosane do not give any indication of the nanoscale structure observed from the wax; the DLS patterns for docosane indicate that a solidification occurs over a very narrow temperature range between 10°C and 12°C, accompanied by a dramatic slowing of the dynamics; the large scale structure seen in the wax mixtures is not evident; and the rheological behavior of the two systems is markedly different. The paper also compares and contrasts the rheological behavior of the wax gel with that observed from defined system, gelled colloidal silica. Strong similarities are apparent.
  • Thumbnail Image
    Item
    A SANS study of the adsorption of guar gum on talc surfaces
    (Australian Nuclear Science and Technology Organisation, 2001-10) Cram, SL; Knott, RB; Hanley, HJM
    Reagents based on guar gum are commonly used as 'gangue' depressants in the flotation of sulphides from ores containing naturally floating layer silicate minerals such as talc. Nickel sulphide ores processed by WMC Resources Ltd. at the Leinster Nickel Operations in Western Australia typically contain 1-2 % talc. Guar gum added to the flotation cell depresses the talc by adsorbing onto its surface thereby reducing its hydrophobic nature. Guar gum is a long chain polysaccharide containing many hydroxyl functional groups along the length of its chain. The ratio of chain length to the number of hydroxyl and carboxyl groups causes the guar gum to be selective in depressing talc rather than nickel sulphide minerals. Small angle neutron scattering (SANS) it is an excellent tool for probing structures in the nano length scale. Unlike X-rays neutrons are sensitive to low atomic weight elements especially hydrogen and therefore organics. Using SANS it is possible to contrast different parts of a composite sample to get information on spatial arrangements. These qualities make SANS an obvious choice for studying the adsorption of guar gum on the surface of talc in aqueous solutions. Complimentary SANS experiments were carried out in Australia at the Australian Nuclear Science and Technology Organisation (ANSTO) and in the United States at the National Institute of Standards and Technology (NIST). Initially talc samples were studied 'as supplied' however as experiments proceeded attempts to reduce the particle size and distribution were carried out by milling and centrifuging procedures. Contrast matching techniques were used to observed the scattering behaviour of talc with and without the presence of guar gum and vice versa over a total q range of 0.002 - 0.1 Angstroms - 1. The size of the talc particles appears to affect the scattering behaviour not only of talc but also of guar gum in the same solutions. This implies that the structure of the guar gum is strongly influenced by the dimensions of the talc and could be taken as indirect evidence of adsorption of guar gum onto the talc surface. Although adsorption has been implied a model of the adsorption mechanism cannot be proposed from these preliminary results. In order to achieve this more homogeneous talc samples need to be studied; in particular the poly dispersity of and impurities in the samples must be addressed.
  • No Thumbnail Available
    Item
    Spray-dried microspheres as a route to clay/polymer nanocomposites
    (Wiley-Blackwell, 2008-05-05) Yun, SI; Attard, DJ; Lo, V; Davis, J; Li, HJ; Latella, BA; Tsvetkov, F; Noorman, H; Moricca, SA; Knott, RB; Hanley, HJM; Morcom, M; Simon, GP; Gadd, GE
    A new strategy for the preparation of well-dispersed clays in a polymer matrix by a spray-drying method is presented. Scanning electron microscopy and transmission electron microscopy measurements show that the spray-drying process produces clay/polymer microspheres in which the clay is trapped in a well-dispersed state throughout the polymer matrix. The microspheres have been successfully extruded into clay/poly(methyl methacrylate) nanocomposite bulk structures without any perturbation of the well-dispersed clay nanostructure in the original microspheres. Transmission electron microscopy and small-angle X-ray scattering show that the clay particles in the extruded materials range from single platelets to simple tactoids composed of a few stacked clay platelets, indicating an excellent degree of dispersion. The results show that sprayed microspheres are very good precursors for further processing such as extrusion or melt blending with other polymers for bulk nanocomposite fabrication. © 2008, Wiley-Blackwell. The definitive version is available at www3.interscience.wiley.com