The role of the dispersed-phase remnant magnetization on the redispersibility of magnetorheological fluids

Phulé, Pradeep P.; Mihalcin, Matthew P.; Genç, Seval

doi:10.1557/jmr.1999.0407

Cited by 58 publications

(43 citation statements)

References 8 publications

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“…It is also significant the reduction of saturation magnetization brought about by the polymer layer: 1582 ± 5 kA/m for carbonyl iron (close to published data obtained with 6 µm particles, see Ref. [35]), and 223.7±1.1 kA/m for core/shell particles. In spite of this expected reduction in magnetic strength, the composite particles meet the proposed requirements: their surface is comparable to that of the pure polymer, but they have the property of being magnetizable, so they constitute an ideal candidate to be used for magnetic drug delivery.…”

Section: Chemical Composition Of the Particlessupporting

confidence: 88%

Preparation and characterization of carbonyl iron/poly(butylcyanoacrylate) core/shell nanoparticles

Arias

Gallardo

Linares-Molinero

et al. 2006

Journal of Colloid and Interface Science

106

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Section: Chemical Composition Of the Particlessupporting

confidence: 88%

Preparation and characterization of carbonyl iron/poly(butylcyanoacrylate) core/shell nanoparticles

Arias

Gallardo

Linares-Molinero

et al. 2006

Journal of Colloid and Interface Science

106

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“…Remnant particles will still stick together when the magnetic field is turned off, and will not therefore show a completely reversible MR effect. Furthermore, the sedimentation stability and redispersibility of remnant particles in a fluid will be less, due to the permanent forces between the particles [23]. The particles should be large enough to support several magnetic domains, otherwise the MR effect will be much smaller, or none at all [21].…”

Section: Particlesmentioning

confidence: 99%

Performance of isotropic magnetorheological rubber materials

2003

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Magnetorheological (MR) rubber materials are controllable composites that consist of magnetically polarisable particles in a rubber matrix. They belong to a group of socalled "smart materials" that have seen an increased interest recently. These materials have rheological properties that can be changed continuously, rapidly and reversibly by an applied magnetic field. With suitable control algorithms and solid state electronics, they can respond to changes in their environment. Although few applications of these materials have yet been reported in the literature, the possibilities for materials with controllable stiffness are numerous. Examples of potential applications are tuned vibration absorbers, and stiffness-tuneable mounts and suspensions.The purpose of this work is to increase our knowledge relating to magnetorheological materials for damping applications, using construction rubber as the matrix. The materials should exhibit large responses to an applied magnetic field and have good mechanical properties. In order to simplify their manufacture, the use of a magnetic field during production should, if possible, be avoided.MR rubber materials were made from nitrile and natural rubber, and irregularly shaped iron particles several micrometers in size. The particles were not aligned by a magnetic field prior to the vulcanisation; hence, the materials can be considered to be isotropic. These materials show a large MR effect, e.g. an increase in the shear modulus when a magnetic field is applied, although the particles are not aligned within the material. This is explained by the low critical particle volume concentration (CPVC) of such particles. Similar behaviour can be obtained with materials containing carbonyl iron, if the particles are aggregated and thereby behave like large irregular particles. The iron particle concentration has to be very close to the CPVC in order to obtain a large MR effect.The absolute MR effect in isotropic MR rubber materials with large irregular iron particles is independent of the matrix material, and the relative MR effect can thus be increased by the addition of plasticisers. Other ways of increasing the MR effect are to increase the strength of the magnetic field, although the materials saturate magnetically at high field strengths, or to use small strain amplitudes. The strong strain amplitude dependence of the MR effect suggests that isotropic MR rubber materials are most suitable for low amplitude applications, such as sound and vibration insulation. Measurements at frequencies within the audible frequency range show that this is a promising application for isotropic MR rubber materials.

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“…Meanwhile, redispersion is one of the biggest challenges in the characterization of MRF [30,31]. It can be described as the capability of an MR suspension to incorporate homogeneously the sediment through the suspension, once the particles have settled, in which the most important thing to determine is the stiffness of the sediment [32]; the lower it is, the easier it is to redisperse by shaking [33].…”

Section: Introductionmentioning

confidence: 99%

Magnetic Nanoparticles as a Redispersing Additive in Magnetorheological Fluid

Portillo

Iglesias

2017

Journal of Nanomaterials

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Unwanted agglomeration of micro particles in magnetorheological fluid is an important problem for many technological applications. Furthermore, the stability of this kind of fluid is also studied as an important property in many research papers. Prior to use, a redispersion of agglomerated or aggregated (connected by solid phase) particles is often necessary. The objective of this study is to evaluate the dispersibility effect of magnetic nanoparticles as a carrier, while keeping the magnetorheological (MR) effect as high as possible. A simple device based on the estimation of the penetration force of a standard needle is presented. The needle moves across the sample vertically with a constant velocity and it is attached to a scale which registers the force displaced by the needle during the dynamic test. The effect with and without other additives was also studied. Transmission electron microscopy (TEM) and Scanning Electron Microscopy (SEM) reveal a protective behavior of nanoparticles around the micro particles. We conclude that addition of magnetic nanoparticles improves the dispersibility characteristic compared with common dispersing additives without affecting the MR effect.

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The role of the dispersed-phase remnant magnetization on the redispersibility of magnetorheological fluids

Cited by 58 publications

References 8 publications

Preparation and characterization of carbonyl iron/poly(butylcyanoacrylate) core/shell nanoparticles

Preparation and characterization of carbonyl iron/poly(butylcyanoacrylate) core/shell nanoparticles

Performance of isotropic magnetorheological rubber materials

Magnetic Nanoparticles as a Redispersing Additive in Magnetorheological Fluid

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