Formation of chain aggregates in magnetic fluids: an influence of polydispersity

The formation of chain-like aggregates in polydisperse ferrofluids is studied theoretically on the basis of the model bidisperse system, consisting of two fractions of small and large ferroparticles. Various topological structures of chains, containing the particles of both fractions, are considered. The equilibrium chain distribution is obtained with the help of the density functional approach. It was found that in real conditions the majority of large particles and the minority of small particles are connected in short chains of 1-3 large particles in the middle and 1-2 small particles at the edges. The chain distribution is greatly dependent on the mole portion of the large particle fraction. (C) 2002 Published by Elsevier Science B.V.