Urano Rio, Chen Kejun, Akama Shota, Takeda Yoshihiro, Maruyama Takayuki, Suzuki Motohiro, Takeuchi Akihisa, Uesugi Masayuki, Kawai Mika, Mitsumata Tetsu
Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
Rigaku Corporation, Tokyo 196-8666, Japan.
Langmuir. 2023 Apr 11;39(14):5137-5144. doi: 10.1021/acs.langmuir.3c00150. Epub 2023 Mar 30.
The relationship between the magnetorheology of bimodal magnetic elastomers with high concentrations (60 vol %) of plastic beads with diameters of 8 or 200 μm and the meso-structure of the particles was investigated. Dynamic viscoelasticity measurements revealed that the change in storage modulus of the bimodal elastomer with 200 μm beads was 2.8 × 10 Pa at a magnetic field of 370 mT. The change in the storage modulus for monomodal elastomer without beads was 4.9 × 10 Pa. The bimodal elastomer with 8 μm beads hardly responded to the magnetic field. In-situ observation for the particle morphology was performed using synchrotron X-ray CT. For the bimodal elastomer with 200 μm beads, a highly aligned structure of magnetic particles was observed in the gaps between the beads when the magnetic field was applied. On the other hand, for the bimodal elastomer with 8 μm beads, no chain structure of magnetic particles was observed. The orientation angle between the long axis of the aggregation of magnetic particles and the magnetic field direction was determined by an image analysis in three dimensions. The orientation angle varied from 56° to 11° for the bimodal elastomer with 200 μm beads and from 64° to 49° for that with 8 μm beads by applying the magnetic field. The orientation angle of the monomodal elastomer without beads changed from 63° to 21°. It was found that the addition of beads with a diameter of 200 μm linked the chains of magnetic particles, while beads with a diameter of 8 μm prevented the chain formation of the magnetic particles.
研究了含有直径为8或200μm的高浓度（60体积%）塑料珠的双峰磁弹性体的磁流变学与颗粒微观结构之间的关系。动态粘弹性测量表明，在370mT的磁场下，含有200μm珠子的双峰弹性体的储能模量变化为2.8×10 Pa。不含珠子的单峰弹性体的储能模量变化为4.9×10 Pa。含有8μm珠子的双峰弹性体几乎不响应磁场。使用同步加速器X射线CT对颗粒形态进行了原位观察。对于含有200μm珠子的双峰弹性体，施加磁场时，在珠子之间的间隙中观察到磁性颗粒的高度排列结构。另一方面，对于含有8μm珠子的双峰弹性体，未观察到磁性颗粒的链状结构。通过三维图像分析确定了磁性颗粒聚集体长轴与磁场方向之间的取向角。施加磁场时，含有200μm珠子的双峰弹性体的取向角从56°变化到11°，含有8μm珠子的双峰弹性体的取向角从64°变化到49°。不含珠子的单峰弹性体的取向角从63°变化到21°。发现添加直径为200μm的珠子连接了磁性颗粒链，而直径为8μm的珠子阻止了磁性颗粒的链形成。
