FIELD-INDUCED FORCES IN COLLOIDAL PARTICLE CHAINS

Electrorheological and magnetorheological effects occur when applied fields polarize particles dissolved in solution. When dipole interaction energies between particles are comparable to thermal energies and particle volume fraction is low, particles align in chains. This paper considers the dipole and higher moment forces within such a chain. We examine forces due to interactions beyond nearest neighbors within a chain, mutual polarization of the particles, and distortion of particle shapes by the applied field. Thermal expansion of the chain enters in the limit of weak applied field. © 1995 The American Physical Society.