Af. Pshenichnikov et Vg. Gilev, RHEOLOGY AND MAGNETIZATION OF CONCENTRATED MAGNETITE COLLOIDS, Colloid journal of the Russian Academy of Sciences, 59(3), 1997, pp. 346-353
The apparent viscosity and magnetization of highly concentrated magnet
ite colloids based on liquid hydrocarbons and oleic acid as a stabiliz
er were experimentally studied. It was shown that the concentration de
pendence of viscosity is most precisely approximated by the Chong form
ula with an adjustment coefficient taking into account the particle ag
gregation. Ignoring the particle aggregation (i.e., interparticle inte
ractions) results in about a twofold underestimation of the apparent v
iscosity. A calculation procedure for saturation magnetization and ini
tial magnetic susceptibility of extremely concentrated colloids was pr
oposed that makes it possible to account for the particle polydispersi
ty and interparticle interactions. Magnetic susceptibility was shown t
o be changed by almost two orders of magnitude depending on the partic
le size distribution. The results of the calculations are in good agre
ement with the experimental data.