Research

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18 pages, 7457 KiB

Open AccessArticle

Dual Electrorheological and Magnetorheological Behaviors of Poly(N-methyl aniline) Coated ZnFe₂O₄ Composite Particles

by Hyun Min Kim, Ji Yoon Jeong, Su Hyung Kang, Hyoung-Joon Jin and Hyoung Jin Choi

Materials 2022, 15(7), 2677; https://doi.org/10.3390/ma15072677 - 05 Apr 2022

Cited by 6 | Viewed by 1837

Magnetic/conducting polymeric hybrid core-shell typed zinc ferrite (ZnFe₂O₄)/poly(N-methyl aniline) (PMA) particles were fabricated and adopted as electrorheological (ER) and magnetorheological (MR) fluids, and their rheological properties were examined. Solvo-thermally synthesized ZnFe₂O₄ was coated with a conducting [...] Read more.

Magnetic/conducting polymeric hybrid core-shell typed zinc ferrite (ZnFe₂O₄)/poly(N-methyl aniline) (PMA) particles were fabricated and adopted as electrorheological (ER) and magnetorheological (MR) fluids, and their rheological properties were examined. Solvo-thermally synthesized ZnFe₂O₄ was coated with a conducting PMA through chemical oxidation polymerization. The size, shape, and chemical composition of the final core-shell shaped particles were scrutinized by scanning electron microscopy, transmission electron microscopy, and Fourier transform-infrared spectroscopy. The crystal faces of the particles before and after coating with PMA were analyzed by X-ray diffraction. The ZnFe₂O₄/PMA products were suspended in silicone oil to investigate the rheological response to electro- or magnetic stimuli using a rotating rheometer. The shear stresses were analyzed using the CCJ equation. The dynamic yield stress curve was suitable for the conductivity mechanism with a slope of 1.5. When magnetic fields of various intensities were applied, the flow curve was analyzed using the Hershel–Bulkley equation, and the yield stresses had a slope of 1.5. Optical microscopy further showed that the particles dispersed in insulating medium form chain structures under electric and magnetic fields. Via this core-shell fabrication process, not only spherical conducting particles were obtained but also their dual ER and MR responses were demonstrated for their wide potential applications. Full article

(This article belongs to the Special Issue Electrorheological and Magnetorheological Performance in Materials Science)

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13 pages, 4037 KiB

Open AccessArticle

Dynamic Response of Polyindole Coated Zinc Ferrite Particle Suspension under an Electric Field

by Su Hyung Kang and Hyoung Jin Choi

Materials 2022, 15(1), 101; https://doi.org/10.3390/ma15010101 - 23 Dec 2021

Cited by 2 | Viewed by 2158

Abstract

ZnFe₂O₄ particles initially synthesized through a simple solvothermal method were coated using polyindole (PIn) to prepare an actively controllable core-shell typed hybrid material under both electric and magnetic fields. An advantage of this process is not needing to add the [...] Read more.

ZnFe₂O₄ particles initially synthesized through a simple solvothermal method were coated using polyindole (PIn) to prepare an actively controllable core-shell typed hybrid material under both electric and magnetic fields. An advantage of this process is not needing to add the stabilizers or surfactants commonly used for uniform coating when synthesizing core or shell-structured particles. The synthesized ZnFe₂O₄/PIn particles have a lower density than conventional magnetic particles and have suitable properties as electrorheological (ER) particles. The expected spherical shape of the particles was proven using both scanning electron microscopy and transmission electron microscopy. The chemical characterization was performed using Fourier-transform infrared spectroscopy and X-ray diffraction analysis. To analyze the rheological properties, a ZnFe₂O₄/PIn based suspension was prepared, and dynamic rheological measurements were performed for different electric field strengths using a rotary rheometer. Both dynamic and elastic yield stresses of the ER fluid had a slope of 1.5, corresponding to the conductivity model. Excellent ER effect was confirmed through rheological analysis, and the prepared ER fluid had a reversible and immediate response to repeated electric fields. Full article

(This article belongs to the Special Issue Electrorheological and Magnetorheological Performance in Materials Science)

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16 pages, 3662 KiB

Open AccessArticle

Loss Factor Behavior of Thermally Aged Magnetorheological Elastomers

by Siti Aishah Abdul Aziz, Saiful Amri Mazlan, Ubaidillah Ubaidillah, Norzilawati Mohamad, Michal Sedlacik, Nur Azmah Nordin and Nurhazimah Nazmi

Materials 2021, 14(17), 4874; https://doi.org/10.3390/ma14174874 - 27 Aug 2021

Cited by 2 | Viewed by 1649

Abstract

Polymer composites have been widely used as damping materials in various applications due to the ability of reducing the vibrations. However, the environmental and surrounding thermal exposure towards polymer composites have affected their mechanical properties and lifecycle. Therefore, this paper presents the effect [...] Read more.

Polymer composites have been widely used as damping materials in various applications due to the ability of reducing the vibrations. However, the environmental and surrounding thermal exposure towards polymer composites have affected their mechanical properties and lifecycle. Therefore, this paper presents the effect of material-temperature dependence on the loss factor and phase shift angle characteristics. Two types of unageing and aging silicone-rubber-based magnetorheological elastomer (SR-MRE) with different concentrations of carbonyl iron particles (CIPs), 30 and 60 wt%, are utilized in this study. The morphological, magnetic, and rheological properties related to the loss factor and phase shift angle are characterized using a low-vacuum scanning electron microscopy, and vibrating sample magnetometer and rheometer, respectively. The morphological analysis of SR-MRE consisting of 30 wt% CIPs revealed a smoother surface area when compared to 60 wt% CIPs after thermal aging due to the improvement of CIPs dispersion in the presence of heat. Nevertheless, the rheological analysis demonstrated inimitable rheological properties due to different in-rubber structures, shear deformation condition, as well as the influence of magnetic field. No significant changes of loss factor occurred at a low CIPs concentration, whilst the loss factor increased at a higher CIPs concentration. On that basis, it has been determined that the proposed changes of the polymer chain network due to the long-term temperature exposure of different concentrations of CIPs might explain the unique rheological properties of the unaged and aged SR-MRE. Full article

(This article belongs to the Special Issue Electrorheological and Magnetorheological Performance in Materials Science)

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14 pages, 3659 KiB

Open AccessArticle

The Effect of Sr-CoFe₂O₄ Nanoparticles with Different Particles Sized as Additives in CIP-Based Magnetorheological Fluid

by Kacuk Cikal Nugroho, Ubaidillah Ubaidillah, Retna Arilasita, Margono Margono, Bambang Hari Priyambodo, Budi Purnama, Saiful Amri Mazlan and Seung-Bok Choi

Materials 2021, 14(13), 3684; https://doi.org/10.3390/ma14133684 - 01 Jul 2021

Cited by 10 | Viewed by 2388

Abstract

This study investigated the effect of adding strontium (Sr)-doped cobalt ferrite (CoFe₂O₄) nanoparticles in carbonyl iron particle (CIP)-based magnetorheological fluids (MRFs). Sr-CoFe₂O₄ nanoparticles were fabricated at different particle sizes using co-precipitation at calcination temperatures of 300 [...] Read more.

This study investigated the effect of adding strontium (Sr)-doped cobalt ferrite (CoFe₂O₄) nanoparticles in carbonyl iron particle (CIP)-based magnetorheological fluids (MRFs). Sr-CoFe₂O₄ nanoparticles were fabricated at different particle sizes using co-precipitation at calcination temperatures of 300 and 400 °C. Field emission scanning electron microscopy (FESEM) was used to evaluate the morphology of the Sr-CoFe₂O₄ nanoparticles, which were found to be spherical. The average grain sizes were 71–91 nm and 118–157 nm for nanoparticles that had been calcinated at 300 and 400 °C, respectively. As such, higher calcination temperatures were found to produce larger-sized Sr-CoFe₂O₄ nanoparticles. To investigate the rheological effects that Sr-CoFe₂O₄ nanoparticles have on CIP-based MRF, three MRF samples were prepared: (1) CIP-based MRF without nanoparticle additives (CIP-based MRF), (2) CIP-based MRF with Sr-CoFe₂O₄ nanoparticles calcinated at 300 °C (MRF CIP+Sr-CoFe₂O₄-T300), and (3) CIP-based MRF with Sr-CoFe₂O₄ nanoparticles calcinated at 400 °C (MRF CIP+Sr-CoFe₂O₄-T400). The rheological properties of these MRF samples were then observed at room temperature using a rheometer with a parallel plate at a gap of 1 mm. Dispersion stability tests were also performed to determine the sedimentation ratio of the three CIP-based MRF samples. Full article

(This article belongs to the Special Issue Electrorheological and Magnetorheological Performance in Materials Science)

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13 pages, 4895 KiB

Open AccessArticle

Magnetite/Poly(ortho-anisidine) Composite Particles and Their Electrorheological Response

by Qi Lu, Jin-Hee Lee, Jin Hyun Lee and Hyoung Jin Choi

Materials 2021, 14(11), 2900; https://doi.org/10.3390/ma14112900 - 28 May 2021

Cited by 7 | Viewed by 1915

Abstract

Magnetic and semiconducting Fe₃O₄/poly(o-anisidine) (POA) core/shell composite particles were fabricated by an oxidation process using Fe₃O₄ synthesized separately. The dispersion stability in a liquid medium and the electrical conductivity of synthesized particles were improved because of [...] Read more.

Magnetic and semiconducting Fe₃O₄/poly(o-anisidine) (POA) core/shell composite particles were fabricated by an oxidation process using Fe₃O₄ synthesized separately. The dispersion stability in a liquid medium and the electrical conductivity of synthesized particles were improved because of the conductive POA polymeric shell. The morphological, microstructural, compositional/elemental, and thermal behaviors of the particles were characterized using SEM with energy dispersive X-ray spectroscopy, TEM, XRD, and thermogravimetric analysis, respectively. A smart electro-magneto-rheological suspension containing Fe₃O₄/POA particles with two functionalities, magnetism and conductivity, was prepared. Its electrorheological properties were investigated at different electric field strengths using a rotational rheometer. Without an electric field, the sample demonstrated typical Newtonian fluid behavior, as expected. However, while under the electric field, it exhibited a solid-like behavior, and the dynamic (or elastic) yield stress of the ER fluid increased linearly as a function of the electric field strength in a power-law function with an index of 2.0, following the polarization mechanism. Full article

(This article belongs to the Special Issue Electrorheological and Magnetorheological Performance in Materials Science)

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13 pages, 3332 KiB

Open AccessArticle

Gelatine-Coated Carbonyl Iron Particles and Their Utilization in Magnetorheological Suspensions

by Tomas Plachy, Patrik Rohrer and Pavlina Holcapkova

Materials 2021, 14(10), 2503; https://doi.org/10.3390/ma14102503 - 12 May 2021

Cited by 4 | Viewed by 2230

Abstract

This study demonstrates the formation of biocompatible magnetic particles into organized structures upon the application of an external magnetic field. The capability to create the structures was examined in silicone-oil suspensions and in a gelatine solution, which is commonly used as a blood [...] Read more.

This study demonstrates the formation of biocompatible magnetic particles into organized structures upon the application of an external magnetic field. The capability to create the structures was examined in silicone-oil suspensions and in a gelatine solution, which is commonly used as a blood plasma expander. Firstly, the carbonyl iron particles were successfully coated with gelatine, mixed with a liquid medium in order to form a magnetorheological suspension, and subsequently the possibility of controlling their rheological parameters via a magnetic field was observed using a rotational rheometer with an external magnetic cell. Scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis confirmed the successful coating process. The prepared magnetorheological suspensions exhibited a transition from pseudoplastic to Bingham behavior, which confirms their capability to create chain-like structures upon application of a magnetic field, which thus prevents the liquid medium from flowing. The observed dynamic yield stresses were calculated using Robertson–Stiff model, which fit the flow curves of the prepared magnetorheological suspensions well. Full article

(This article belongs to the Special Issue Electrorheological and Magnetorheological Performance in Materials Science)

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20 pages, 4473 KiB

Open AccessEditor’s ChoiceArticle

Novel Approaches to the Design of an Ultra-Fast Magnetorheological Valve for Semi-Active Control

by Zbyněk Strecker, Filip Jeniš, Michal Kubík, Ondřej Macháček and Seung-Bok Choi

Materials 2021, 14(10), 2500; https://doi.org/10.3390/ma14102500 - 12 May 2021

Cited by 22 | Viewed by 2410

Abstract

This article presents a list of suitable techniques and materials leading to the design of an ultra-fast magnetorheological (MR) valve. Two approaches for achieving the short response time are proposed: (a) by means of material, and (b) by means of the shape. Within [...] Read more.

This article presents a list of suitable techniques and materials leading to the design of an ultra-fast magnetorheological (MR) valve. Two approaches for achieving the short response time are proposed: (a) by means of material, and (b) by means of the shape. Within the shape approach, the revolutionary technique of 3D metal printing using a selective laser melting (SLM) method was tested. The suitability of the materials and techniques is addressed based on the length of the response time, which is determined by the FEM. The simulation results determine the response time of the magnetic flux density on the step signal of the current. Subsequently, the response time is verified by the measurement of the simple magnetorheological valve. The following materials were tested: martensitic stainless steel AISI 420A (X20Cr13), cutting steel 11SMn30, pure iron for SLM, Sintex SMC STX prototyping material, ferrite N87, and Vacoflux 50. A special technique involving grooves was used for preventing eddy currents on materials with a high electrical conductivity. The simulation and experimental results indicate that a response time shorter than 2.5 ms can be achieved using materials such as Sintex SMC prototyping, ferrite N87, and grooved variants of metal pistons. Full article

(This article belongs to the Special Issue Electrorheological and Magnetorheological Performance in Materials Science)

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Review

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20 pages, 8476 KiB

Open AccessReview

Electrorheological Fluids of GO/Graphene-Based Nanoplates

by Yudong Wang, Jinhua Yuan, Xiaopeng Zhao and Jianbo Yin

Materials 2022, 15(1), 311; https://doi.org/10.3390/ma15010311 - 02 Jan 2022

Cited by 10 | Viewed by 1892

Abstract

Due to their unique anisotropic morphology and properties, graphene-based materials have received extensive attention in the field of smart materials. Recent studies show that graphene-based materials have potential application as a dispersed phase to develop high-performance electrorheological (ER) fluids, a kind of smart [...] Read more.

Due to their unique anisotropic morphology and properties, graphene-based materials have received extensive attention in the field of smart materials. Recent studies show that graphene-based materials have potential application as a dispersed phase to develop high-performance electrorheological (ER) fluids, a kind of smart suspension whose viscosity and viscoelastic properties can be adjusted by external electric fields. However, pure graphene is not suitable for use as the dispersed phase of ER fluids due to the electric short circuit caused by its high electrical conductivity under electric fields. However, graphene oxide (GO) and graphene-based composites are suitable for use as the dispersed phase of ER fluids and show significantly enhanced property. In this review, we look critically at the latest developments of ER fluids based on GO and graphene-based composites, including their preparation, electrically tunable ER property, and dispersed stability. The mechanism behind enhanced ER property is discussed according to dielectric spectrum analysis. Finally, we also propose the remaining challenges and possible developments for the future outlook in this field. Full article

(This article belongs to the Special Issue Electrorheological and Magnetorheological Performance in Materials Science)

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