Journal of Materials Science

, Volume 44, Issue 22, pp 6100–6109 | Cite as

The influence of stearic acid coating on the properties of magnesium hydroxide, hydromagnesite, and hydrotalcite powders

  • Walter W. FockeEmail author
  • Dan Molefe
  • F. J. W. Labuschagne
  • Shatish Ramjee


Hydrated filler-type flame retardants were coated with approximately a monolayer of stearic acid using a solvent technique. Compared to the uncoated powders, the BET surface area was lower, the powder packing density was improved, and the thickening effect on white oil was significantly reduced. The latter two observations are rationalized in terms of a reduction in the attractive interactions between the powder particles. The viscosity of white oil slurries containing 25 wt% solids showed shear-thinning non-Newtonian behavior. The coated powders showed significantly lower viscosities at low shear rates although the difference diminished at high shear rates. The lower viscosities shown by the coated powders indicate that the surface modification facilitated the break-up of agglomerates and the dispersion of individual particles in the fluid.


Shear Rate Stearic Acid Flame Retardant Layered Double Hydroxide Hydrotalcite 



Financial support for this research, from the Institutional Research Development Programme (IRDP) of the National Research Foundation of South Africa (NRF) and the THRIP program of the Department of Trade and Industry (administered by the NRF), is gratefully acknowledged.


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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Walter W. Focke
    • 1
    Email author
  • Dan Molefe
    • 2
  • F. J. W. Labuschagne
    • 1
  • Shatish Ramjee
    • 1
  1. 1.Department of Chemical Engineering, Institute of Applied MaterialsUniversity of PretoriaPretoriaSouth Africa
  2. 2.Department of ChemistryUniversity of PretoriaPretoriaSouth Africa

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