Enhancement of magnetic losses in hybrid polymer composites with MnZn-ferrite and conductive fillers
Enhancement of magnetic losses in hybrid polymer composites with MnZn-ferrite and conductive fillers
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DOI：
10.1007/s10853-007-2081-0
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发表时间：
2007-08
影响因子：
4.5
通讯作者：
R. Moučka;A. Lopatin;N. Kazantseva;J. Vilčáková;P. Sáha
中科院分区：
文献类型：
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作者：
R. Moučka;A. Lopatin;N. Kazantseva;J. Vilčáková;P. Sáha
制备了以磁性填料(锰锌铁氧体)填充的聚氨酯(PU)为基质的聚合物复合材料(PC)，以及该磁性填料与各种导电填料(炭黑、碳纤维、铝粉、聚吡咯)组成的杂化聚合物复合材料(HPC)。高性能混凝土的基质结构是(I)由填充了导电填料的聚合物形成的，该导电填料形成无限团簇的骨架，以及(Ii)由比导电颗粒大的铁氧体颗粒形成。因此，HPC代表铁氧体颗粒的集合，每个铁氧体颗粒被导电介质包围，可以被认为是“核-壳”结构。与填充导电填料的PU相比，HPC中的电渗流阈值较低，这证明了核壳结构的发展。在1 GHz~10 GHz的频率范围内，研究了PC和HPC的磁谱和介电谱。与PC相比，混合系统显示出相当大的磁损耗增强。高性能混凝土中磁损耗的增加是由于微波磁场在导电壳体中感应的传导电流所致。
Polymer composites (PCs) with a polyurethane (PU) matrix filled with magnetic filler (MnZn ferrite) and hybrid polymer composites (HPCs) consisting of this magnetic filler and various types of conductive fillers (carbon black, carbon fibers, aluminum powder, polypyrrole) are prepared. The matrix structure of a HPC is formed (i) by a polymer filled with conductive filler, which forms the skeleton of an infinite cluster, and (ii) by ferrite particles that are larger than conductive particles. Thus, an HPC represents an ensemble of ferrite particles each of which is surrounded by a conductive medium and can be considered as a “core–shell” structure. The development of a core–shell structure is evidenced by the lower electric percolation threshold in an HPC compared with that in PU filled with conductive filler. Magnetic and dielectric spectra of PCs and HPCs are studied in the frequency range from 1 MHz to 10 GHz. Hybrid systems exhibit a considerable enhancement of magnetic losses compared with PCs. The enhancement of magnetic losses in HPCs is due to the conduction currents that are induced in the conductive shell by a microwave magnetic field.