Factors influencing the low-temperature fluidity of kerosene-based magnetic fluid: Surfactant, volume fraction

Abstract

To explore the effect factors on the fluidity of magnetic fluid at low temperatures, the magnetic fluid was prepared by dispersing stearic acid and oleic acid-modified particles into kerosene, the effect of volume fraction was also considered. The microstructure and morphology of the particles were obtained by XRD and TEM, and the surfactant content on the surface of the particles was determined by TG. The hysteresis loops of magnetic particles and magnetic fluids were obtained by VSM. As the temperature decreased, it was observed that the magnetic fluid with a high volume fraction of stearic acid-modified particles would lose fluidity quickly under a non-magnetic field. But it could respond to a certain magnetic field, and the fluidity could be restored quickly by increasing the temperature. The rheometer measured the viscosity of the magnetic fluid-dependent temperature, shear rate, and magnetic field. When a high melting point of stearic acid coated particles, the stearic acid with adequate chain length could affect the fluidity of magnetic fluid with a volume fraction greater than 5% at roughly 20 °C. The free surfactant formed micelle, the base carrier was restricted in the particles adhering to the micelles, eventually causing the magnetic fluid to lose fluidity.