Shevchenko Vitaliy G, Stepanov Gennady V, Kramarenko Elena Yu
Enikilopov Institute of Synthetic Polymeric Materials of Russian Academy of Sciences (ISPM RAS), 117393 Moscow, Russia.
State Scientific Center of the Russian Federation, Institute of Chemistry and Technology of Organoelement Compounds, 111123 Moscow, Russia.
Polymers (Basel). 2021 Jun 18;13(12):2002. doi: 10.3390/polym13122002.
Dielectric properties of two series of magnetoactive elastomers (MAEs) based on a soft silicone matrix containing 35 vol% of magnetic particles were studied experimentally in a wide temperature range. In the first series, a hybrid filler representing a mixture of magnetically hard NdFeB particles of irregular shape and an average size of 50 μm and magnetically soft carbonyl iron (CI) of 4.5 μm in diameter was used for MAE fabrication. MAEs of the second series contained only NdFeB particles. The presence of magnetically hard NdFeB filler made it possible to passively control MAE dielectric response by magnetizing the samples. It was shown that although the hopping mechanism of MAEs conductivity did not change upon magnetization, a significant component of DC conductivity appeared in the magnetized MAEs presumably due to denser clustering of interacting particles resulting in decreasing interparticle distances. The transition from a non-conducting to a conducting state was more pronounced for hybrid MAEs containing both NdFeB and Fe particles with a tenfold size mismatch. Hybrid MAEs also demonstrated a considerable increase in the real part of the complex relative permittivity upon magnetization and its asymmetric behavior in external magnetic fields of various directions. The effects of magnetic filler composition and magnetization field on the dielectric properties of MAEs are important for practical applications of MAEs as elements with a tunable dielectric response.
在很宽的温度范围内，对基于含有35体积%磁性颗粒的软硅橡胶基体的两个系列的磁活性弹性体（MAE）的介电性能进行了实验研究。在第一个系列中，一种混合填料用于制造MAE，该混合填料是不规则形状且平均尺寸为50μm的硬磁钕铁硼颗粒与直径为4.5μm的软磁羰基铁（CI）的混合物。第二个系列的MAE仅包含钕铁硼颗粒。硬磁钕铁硼填料的存在使得通过对样品进行磁化来被动控制MAE的介电响应成为可能。结果表明，尽管MAE电导率的跳跃机制在磁化后没有改变，但在磁化的MAE中出现了显著的直流电导率分量，这可能是由于相互作用颗粒的更密集聚集导致颗粒间距离减小。对于同时包含尺寸相差十倍的钕铁硼和铁颗粒的混合MAE，从非导电状态到导电状态的转变更为明显。混合MAE在磁化后还表现出复相对介电常数实部的显著增加以及在不同方向外部磁场中的不对称行为。磁填料组成和磁化场对MAE介电性能的影响对于MAE作为具有可调介电响应的元件的实际应用很重要。
