Three-dimensional morphology of field-induced chain-like aggregates of superparamagnetic microparticles

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 358; no. 1; pp. 21 - 27
• Main Authors: Domínguez-García, P., Rubio, M.A.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 05.04.2010; Elsevier
• Subjects: Aggregates; Chains; Chemistry; Colloidal state and disperse state; Exact sciences and technology; Fluid flow; Fractal aggregates; Fractal analysis; Fractals; General and physical chemistry; Irreversible aggregation; Light scattering; Magnetic colloids; Magnetic fields; Magneto-rheological fluids; Morphology; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Projected fractal dimension; Surface physical chemistry; Three-dimensional fractal dimension; Fractal aggregates; Projected fractal dimension; Magnetic colloids; Magneto-rheological fluids; Irreversible aggregation; Three-dimensional fractal dimension; Water; Small angle light scattering; Industrial application; Light scattering; Fluid; Superparamagnetism; Aggregation; Particle; Image analysis; Fractal; Magnetic colloid; Fractal dimension; Morphology; Microparticle; Aggregate; Magnetic field
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2010.01.018

We develop a study concerning the three-dimensional morphology of chain-like aggregates formed by 1 μ m-sized super-paramagnetic particles suspended in water under the action of a constant uniaxial magnetic field. This kind of fluids are known as magneto-rheological fluids (MRF) and are present in many industrial and technological applications. In order to characterize the morphology of the aggregates, the fractal dimension, D f , is obtained by a simple implementation of the small angle light scattering (SALS) technique with a CCD Camera. In the experiments, the values of the magnetic field amplitude and particle concentration are changed, finding that the fractal dimension depends on the ratio of two characteristic lengths, R 1 / R 0 . Besides, we also discuss the relation between 3D (obtained by light scattering) and 2D (obtained by image analysis) fractal dimensions for the case of these anisotropic aggregates.