Enhancement of magnetic losses in hybrid polymer composites with MnZn-ferrite and conductive fillers

• Published in: Journal of materials science Vol. 42; no. 22; pp. 9480 - 9490
• Main Authors: Moucka, Robert, Lopatin, Alexander V, Kazantseva, Natalia E, Vilcakova, Jarmila, Saha, Petr
• Format: Journal Article
• Language: English
• Published: New York Springer Nature B.V 01.11.2007
• Subjects: Aluminum; Carbon black; Carbon fibers; Core-shell structure; Ferrite; Ferrites; Fillers; Frequency ranges; Hybrid systems; Materials science; Particulate composites; Percolation; Plutonium; Polymer matrix composites; Polymers; Polypyrroles; Polyurethane resins; Repair & maintenance; Shells
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-007-2081-0

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.