Investigation of concentration and surfactant quality influence on magnetic particle agglomeration in ferrofluids from static linear dichroism experiments

In this paper we report on static linear dichroism of two ferrofluids with ferrite particles stabilized with pure and technical grade oleic acid, respectively, and immersed in transformer oil. A theoretical model for the static linear dichroism was developed in order to account for both magnetic particle orientation and agglomeration processes contributions to the magnetically induced optical anisotropy of ferrofluids. The relative weight of the orientation and agglomeration processes was found to be influenced by the magnetic particle volume fraction and the quality of the surfactant. (C) 1999 Elsevier Science B.V. All rights reserved.