Graduate School of Science and Technology, Niigata University , Niigata 950-2181, Japan.
ALCA, Japan Science and Technology Agency , Tokyo 102-0076, Japan.
J Phys Chem B. 2017 Feb 23;121(7):1740-1747. doi: 10.1021/acs.jpcb.6b12875. Epub 2017 Feb 13.
The electric-voltage dependence of the electric conductivity for cross-linked and un-cross-linked magnetic elastomers was measured at various magnetic fields, and the effect of cross-linking on the electric conductivity and the dielectric-breakdown behavior was investigated. The electric conductivity for un-cross-linked elastomers at low voltages was independent of magnetic fields and the volume fraction of magnetic particles, indicating the electric conduction in the polyurethane matrix. At high voltages, the electric conductivity increased with the magnetic field, showing the electric conduction via chains of magnetic particles. On the other hand, the electric conductivity at low voltages for cross-linked elastomers with volume fractions below 0.06 was independent of the magnetic field, suggesting the electric conduction in the polyurethane matrix. At volume fractions above 0.14, the electric conductivity increased with the magnetic field, suggesting the electric conduction via chains of magnetic particles. At high voltages, the electric conductivity for cross-linked elastomers with a volume fraction of 0.02 was independent of the magnetic field, indicating the electric conduction through the polyurethane matrix. At volume fractions above 0.06, the electric conductivity suddenly increased at a critical voltage, exhibiting the dielectric breakdown at the bound layer of magnetic particles and/or the discontinuous part between chains.
交联和未交联磁弹性体的电导率随电压的变化在不同磁场下进行了测量，并研究了交联对电导率和介电击穿行为的影响。在低电压下，未交联弹性体的电导率与磁场和磁性粒子的体积分数无关，表明在聚氨酯基体中存在电导。在高电压下，电导率随磁场的增加而增加，表明通过磁性粒子链进行电导。另一方面，在体积分数低于 0.06 的交联弹性体中，在低电压下的电导率与磁场无关，表明在聚氨酯基体中存在电导。在体积分数高于 0.14 时，电导率随磁场的增加而增加，表明通过磁性粒子链进行电导。在体积分数为 0.02 的交联弹性体中，在高电压下，电导率与磁场无关，表明通过聚氨酯基体进行电导。在体积分数高于 0.06 时，电导率在临界电压下突然增加，在磁性粒子的结合层和/或链之间的不连续部分表现出介电击穿。
