Chain Structure in a Cross-Linked Polyurethane Magnetic Elastomer Under a Magnetic Field

Watanabe, Mayuko; Takeda, Yoshihiro; Maruyama, Takayuki; Ikeda, Junko; Kawai, Mika; Mitsumata, Tetsu

doi:10.3390/ijms20122879

Cited by 24 publications

(27 citation statements)

References 28 publications

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“…The distance between the nearest neighbor beads was calculated to be 31 μm. Magnetic particles are forced to be localized in the vacancy and form a chain structure by the magnetic field, for example, a qualitative representation of the microstructure [17] and computed tomography images [18]. In our previous study, the storage modulus for bimodal magnetic elastomers containing small nonmagnetic particles (1.4 or 10.6 μm in diameter) gradually increased with the volume fraction of nonmagnetic particles, and a clear percolation threshold was not observed.…”

Section: Resultsmentioning

confidence: 92%

Efficient Chain Formation of Magnetic Particles in Elastomers with Limited Space

et al. 2020

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The magnetic response of the storage modulus for bimodal magnetic elastomers containing magnetic particles with a diameter of 7.0 μm and plastic beads with a diameter of 200 μm were investigated by varying the volume fraction of plastic beads up to 0.60 while keeping the volume fraction of the magnetic particles at 0.10. The storage modulus at 0 mT for monomodal magnetic elastomers was 1.4 × 104 Pa, and it slightly increased with the volume fraction of plastic beads up to 0.6. The storage modulus at 500 mT for bimodal magnetic elastomers at volume fractions below 0.25 was constant, which was equal to that for the monomodal one (=7.9 × 104 Pa). At volume fractions of 0.25–0.40, the storage modulus significantly increased with the volume fraction, showing a percolation behavior. At volume fractions of 0.40-0.60, the storage modulus was constant at 2.0 × 105 Pa, independently of the volume fraction. These results indicate that the enhanced increase in the storage modulus was caused by the chain formation of the magnetic particles in vacancies made of plastic beads.

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Section: Resultsmentioning

confidence: 92%

Efficient Chain Formation of Magnetic Particles in Elastomers with Limited Space

et al. 2020

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“…The increase in the storage modulus is due to the chain formation of magnetic particles by magnetic fields. In fact, we successfully observed the chain structure of magnetic particles in a magnetic elastomer using computed tomography at high resolution [16].…”

Section: Resultsmentioning

confidence: 99%

Particle Size in Secondary Particle and Magnetic Response for Carrageenan Magnetic Hydrogels

Ikeda

Takahashi

Watanabe

et al. 2019

Gels

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The relation between the number of magnetic particles and the change in storage modulus induced by a magnetic field was investigated for weak hydrogels containing carbonyl iron, iron oxide, and barium ferrite particles with different diameters in primary particles while maintaining the magnetization of magnetic particles. The change in storage modulus exhibited a power dependency against the number of magnetic particles, which was nearly independent of the magnetic particles. The change in storage modulus was successfully scaled by the reduced number of magnetic particles using the diameter of secondary particles. Microphotographs revealed that iron oxide and barium ferrite particles form aggregations while carbonyl iron particles are well dispersed in carrageenan gels. The diameter of secondary particles determined by a relation between the change in storage modulus and the reduced number of magnetic particles showed similar values with those observed in microphotographs.

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“…A similar trend in particle morphology was also observed for the enlarged photographs in Figure 6(k) and 6(l). We reported a result of in-situ observation by computed tomography that magnetic particles form a chain structure within polyurethane elastomers by applying a magnetic field [31]. It is well known that sea cucumbers have hard collagen tissues in their soft dermis to protect themselves from enemies.…”

Section: Resultsmentioning

confidence: 99%

Magnetic Elastomers with Smart Variable Elasticity Mimetic to Sea Cucumber

et al. 2019

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A magnetic-responsive elastomer consisting of magnetic elastomer and zinc oxide with a tetrapod shape and long arms was fabricated mimetic to the tissue of sea cucumber in which collagen fibrils are dispersed. Only the part of magnetic elastomer is active to magnetic fields, zinc oxide plays a role of reinforcement for the chain structure of magnetic particles formed under magnetic fields. The magnetic response of storage modulus for bimodal magnetic elastomers was measured when the magnetic particle was substituted to a nonmagnetic one, while keeping the total volume fraction of both particles. The change in storage modulus obeyed basically a mixing rule. However, a remarkable enhancement was observed at around the substitution ratio of 0.20. In addition, the bimodal magnetic elastomers with tetrapods exhibited apparent change in storage modulus even at regions with a high substitution ratio where monomodal magnetic elastomers consist of only magnetic particles with less response to the magnetic field. This strongly indicates that discontinuous chains of small amounts of magnetic particles were bridged by the nonmagnetic tetrapods. On the contrary, the change in storage modulus for bimodal magnetic elastomers with zinc oxide with irregular shape showed a mixing rule with a substitution ratio below 0.30. However, it decreased significantly at the substitution ratio above it. The structures of bimodal magnetic elastomers with tetrapods and the tissue of sea cucumber with collagen fibrils are discussed.

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Chain Structure in a Cross-Linked Polyurethane Magnetic Elastomer Under a Magnetic Field

Cited by 24 publications

References 28 publications

Efficient Chain Formation of Magnetic Particles in Elastomers with Limited Space

Efficient Chain Formation of Magnetic Particles in Elastomers with Limited Space

Particle Size in Secondary Particle and Magnetic Response for Carrageenan Magnetic Hydrogels

Magnetic Elastomers with Smart Variable Elasticity Mimetic to Sea Cucumber

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