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Title: Quantification of branching in fumed silica

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Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
National Science Foundation (NSF)
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Aerosol Science; Journal Volume: 109; Journal Issue: C
Country of Publication:
United States

Citation Formats

Mulderig, Andrew, Beaucage, Gregory, Vogtt, Karsten, Jiang, Hanqiu, and Kuppa, Vikram. Quantification of branching in fumed silica. United States: N. p., 2017. Web. doi:10.1016/j.jaerosci.2017.04.001.
Mulderig, Andrew, Beaucage, Gregory, Vogtt, Karsten, Jiang, Hanqiu, & Kuppa, Vikram. Quantification of branching in fumed silica. United States. doi:10.1016/j.jaerosci.2017.04.001.
Mulderig, Andrew, Beaucage, Gregory, Vogtt, Karsten, Jiang, Hanqiu, and Kuppa, Vikram. 2017. "Quantification of branching in fumed silica". United States. doi:10.1016/j.jaerosci.2017.04.001.
title = {Quantification of branching in fumed silica},
author = {Mulderig, Andrew and Beaucage, Gregory and Vogtt, Karsten and Jiang, Hanqiu and Kuppa, Vikram},
abstractNote = {},
doi = {10.1016/j.jaerosci.2017.04.001},
journal = {Journal of Aerosol Science},
number = C,
volume = 109,
place = {United States},
year = 2017,
month = 7
  • Suspensions of fumed silica exhibit a wide range of rheological properties, depending on the type of microstructure present. At high silica concentrations, the rheological behavior is ``gel-like,`` due to the formation of a network consisting of interconnected silica flocs. When large amplitude oscillatory preshear is applied on these systems, the network linkages are disrupted, resulting in the formation of isolated flocs. In this study, we focus on the extent to which the network is restored on cessation of preshear. By applying small amplitude oscillations we can study the development of the elastic modulus ({ital G}{prime}) with time, following disruptive shear.more » We find that the restoration of the network after preshear is instantaneous; however, {ital G}{prime} recovers to different levels depending on the amplitude of the imposed preshear strain. Contrary to expectations, larger preshear strains (which cause a greater degree of microstructural disruption) do not always lead to lower levels of recovered {ital G}{prime}. For strains greater than a critical value, the recovered {ital G}{prime} progressively increases with increasing preshear strain. This anomalous behavior of the elastic modulus is explained in terms of microstructural rearrangements that may occur during oscillatory preshear. {copyright} {ital 1995} {ital Society} {ital of} {ital Rheology}« less
  • Suspensions of fumed silica in polypropylene glycol exhibit shear-thickening under steady shear and strain-thickening under oscillatory shear. Strain-thickening refers to a sharp increase in the complex viscosity {eta}* observed at critical combinations of strain-amplitude and frequency. Two regimes of strain-thickening behavior have been found: The first occurs at high critical strains and low frequencies, whereas the second occurs at high critical frequencies and a constant lower strain. Strain-thickening in the first regime can be explicitly correlated with steady shear-thickening, using a modified version of the Cox-Merz rule. Accordingly, strain-thickening data for the complex viscosity {eta}* as a function of themore » maximum dynamic shear-rate {gamma}{sub 0}{omega} can be superposed against shear-thickening data for the steady viscosity as a function of the steady shear rate. Such a correlation between the two kinds of thickening phenomena has not been reported previously. The combination of shear- and strain-thickening behavior can be qualitatively explained using a clustering mechanism, which attributes the various phenomena to the formation of temporary, flow-induced clusters. The two regimes of strain-thickening are a result of differences in the relative ease of cluster formation.« less
  • The conductivity of solution electrolytes containing lithium salts (imide and triflate anions), poly(ethylene glycol), and mono- and dimethyl-terminated poly(ethylene glycol) (Mw 200 to 400), and their corresponding composite electrolytes containing fumed-silica particulates (0 to 20 weight percent) are reported. At room temperature the ionic conductivity is as high as 1.5 {times} 10{sup {minus}3} S/cm for the composites studied, and they exhibit a gel-like consistency but flow under shear. The electrochemical stability of the composites and compatibility with lithium metal were also examined. A large potential window ({approximately}5.5 V) was found for Li imide-based electrolytes. The passive film formed on lithiummore » in contact with the composite electrolyte is relatively more stable and less resistive than that formed in contact with the parent solution electrolyte. Considering the additional advantages of processability and low volatility, these composites should be good candidate electrolytes for lithium and lithium ion batteries.« less
  • A new and simple type of substrate for surface-enhanced raman scattering (SERS) was investigated. This new substrate is based upon silver-coated fumed silica on surfaces such as glass plates or microscopic slides. Fumed silica, which has submicrometer size structure provides the surface roughness necessary for SERS process. The effects of several experimental factors, including the type of fumed silica, the concentration of the microparticles, and the silver layer thickness were investigated. The SERS spectra of various organic species were used to demonstrate the efficiency and applicability of the new substrate. Fumed-silica-based substrates offer many advantages, since they are simple tomore » prepare and easy to handle. The basic material, fumed silica, is also commercially available at very low cost.« less