Stabilization of magnetorheological suspensions by polyacrylic acid polymers (original) (raw)
Related papers
Structural Aspects of Stabilization of Magnetic Fluids by Mono-Carboxylic Acids
Solid State Phenomena, 2009
The structure of magnetic fluids (magnetite in decahydronaphtalene) stabilized with saturated mono-carboxylic acids of different chain lengths (lauric, myristic, palmitic and stearic acids) is studied by means of magnetization analysis and small-angle neutron scattering. It is shown that magnetite nanoparticles are dispersed in the carrier approximately with the same size distribution whose mean value and width are significantly less as compared to the classical stabilization with non-saturated oleic acid. The found thickness of the surfactant shell around magnetite is analyzed with respect to stabilizing properties of mono-carboxylic acids.
Studies of the double surfactant layer stabilization of water-based magnetic fluids
Journal of colloid and interface …, 1991
A comparison of the ability of C6-Cj8 carboxylic acids to stabilize aqueous magnetite fluids is made. Micelle formation prevented complete dispersion of magnetite by stearic and myristic acids, but was overcome by introducing the acid in several portions. Improvements in fluid preparation are reported, achieved by perchloric acid treatment of surfactant-stabilized magnetite produced in basic solution, followed by redispersion of the particles in dilute base. The quantity of surfactant in the primary layer has been determined for C~0-Cl8 acids, and the particle surface area occupied per molecule of surfactant found to range between ca. 21 and 38 ~2. For decanoic and myristic acids the groups pack efficiently and form a "condensed" film over the surface of the particles. Ammonium and monomethylammonium salts of the same acids were used in attempts to form the secondary layers. Ammonium salts produced dispersion in all cases except Sarkosyl-"O," whereas MeNH~ salts of oleic and myristic acids were successful. Quantitative data on the relative amounts of surfactant in each layer are presented and discussed.
Sterically stabilized water based magnetic fluids: Synthesis, structure and properties
Journal of Magnetism and Magnetic Materials, 2007
Magnetic fluids (MFs), prepared by chemical co-precipitation followed by double layer steric and electrostatic (combined) stabilization of magnetite nanoparticles dispersed in water, are presented. Several combinations of surfactants with different chain lengths (lauric acid (LA), myristic acid (MA), oleic acid (OA) and dodecyl-benzene-sulphonic acid (DBS)) were used, such as LA+LA, MA+MA, LA+DBS, MA+DBS, OA+DBS, OA+OA and DBS+DBS. Static light scattering, transmission electron microscopy, small angle neutron scattering, magnetic and magneto-rheological measurements revealed that MFs with MA+MA or LA+LA biocompatible double layer covered magnetite nanoparticles are the most stable colloidal systems among the investigated samples, and thus suitable for biomedical applications. r
Designing magnetic composite materials using aqueous magnetic fluids
In this paper, we report how to take advantage of the good knowledge of both the chemistry and the stability of an aqueous magnetic colloidal suspension to realize different magnetic composites. The osmotic pressure of the magnetic nanoparticles is set prior to the realization of the composite to a given value specially designed for the purpose of each hybrid material: magnetic particles in polymer networks, particles as probes for studying the structure of clay suspensions and shape modification of giant liposomes.
Concentrated magnetic fluids on water and short chain length organic carriers
Journal of Magnetism and Magnetic Materials, 2005
Magnetic fluids on methyl-ethyl-ketone, ethylic ether, i-propanol, i-butanol and water were prepared applying double layer of surfactants to ensure the colloidal stability of samples of saturation magnetization up to 50 kA/m. Magnetooptical, magnetic, rheological and magnetorheological measurements evidence the different behaviour of samples depending on the polarity of carriers, concentration and combination of surfactant bilayers.
Advances in Magnetorheological Suspension: Production and Properties
Journal of Industrial and Engineering Chemistry, 2006
Magnetorheological suspensions (MRSs) are polyphasic fluids. They are made up of additives and magnetic particles dispersed in a carrier liquid. MRSs modify its fluidity in the magnetic field, a property which is used in vibration dampers and mechanical shocks, clutches etc. MRSs, together with electrorheological fluids (ERF), stand out as a material of great scientific and applicative importance. Every two years there takes place international conferences entitled “International Conference on ERF and MRSs”. The papers presented on these occasions stand out as an actual progress in MRSs obtaining, characterizing, modelling and applications. This paper proposes, without exhausting the approached theme, to present achievements and future perspectives concerning MRSs obtaining and mechanisms which make them be characterized by properties that are of interest for applications.
Magnetic emulsions with responsive surfactants
Soft Matter, 2012
Emulsions are mixtures of two or more immiscible fluids, stabilised by interfacial adsorption of surfactants or particles. As such emulsions are essential components in multifarious processes and products, such as foods, pharmaceutical and agrochemical formulations, paints, inks, lubricants, oils and oil recovery. Stability and structure of responsive colloids and emulsions can be controlled by changes in composition, pH, as well as by external stimuli temperature, pressure and light. This is the first report of easy to formulate magnetically responsive emulsions stabilized by a new class of magnetic surfactant stabilizers.
Experimental Study of Stearic Acid Effect on Stabilization of Magnetorheological Fluids (MRFs)
Magnetorheological fluids (MRFs) are materials which respond to an external magnetic field with considerable change in their rheological properties. In this paper, a new type of MRF was synthesized by dispersing carbonyl iron particles in silicon oil with stearic acid as stabilizer. Rheological properties of this suspension under different magnetic field strength were studied by using a rotational rheometer. Experimental studies showed that using stearic acid not only enhances shear stress, but also considerably improves the suspension stability.
International Journal of Thermophysics, 2012
The effect of the molecular weight of poly(ethylene glycol) (PEG) on the physical properties of water-based magnetic fluids with sodium oleate and PEG stabilization was investigated. The structure as well as magnetic, rheological, and thermal properties of the obtained samples were studied using transmission electron microscopy (TEM), photon cross correlation spectroscopy (PCCS), superconducting quantum interference device (SQUID), and differential scanning calorimetry (DSC) methods. The molecular weight of PEG had a strong effect on the rheological properties while the effect was rather insignificant on the particle size distribution and the self-heating of the studied magnetic fluids. The heating ability of the PEG-stabilized magnetic fluids was determined by calorimetric measurements of the specific absorption rate (SAR). The thickness of the PEG layer was calculated from the experimental data of the temperature rise rates as a function of the magnetic field strength using the Rosensweig theory.
Journal of Applied Polymer Science, 2006
Magnetorheological (MR) fluids based on glycol, iron powder, polyvinylpyrrolidone (PVP), and carbon nanotubes (CNTs) were prepared. Effects of polyvinylpyrrolidone and carbon nanotubes on sedimentation stability and magnetorheological properties were studied. It is found that the synergetic effects of PVP and CNTs improve the sedimentation stability significantly, and the addition of CNTs reduces the sedimentation velocity and increases the equilibrium sedimentation ratio of the magnetizable particles in MR fluids remarkably. The addition of PVP can reduce the sedimentation velocity of the magnetizable particles, but cannot increase the equilibrium sedimentation ratio and will not change the up trend of apparent viscosity with the increasing intensity of the external magnetic field.