Microwave absorbing property and complex permittivity and permeability of epoxy composites containing Ni-coated and Ag filled carbon nanotubes

Microwave absorbing property, complex permittivity, and permeability of epoxy composites containing Ni-coated and Ag nanowires filled carbon nanotubes (CNTs) have been investigated. CNTs were coated with nickel by an electroless plating technique, whereas CNTs were filled with Ag nanowires via a wet chemical method. Compared with the CNTs/epoxy composites, the real part (ε′) and imaginary part (ε″) of the complex permittivity as well as dielectric dissipation factor (tgδε = ε″/ε′) of the epoxy composites containing the Ni–P coated CNTs were much smaller, while the real part (μ′) and imaginary part (μ″) of the complex permeability and the magnetic dissipation factor (tgδμ = μ″/μ′) were greater. The microwave absorption enhancement of Ni-coated CNTs/epoxy composites resulted from dielectric and magnetic losses. In contrast, the microwave absorption of Ag nanowire-filled CNTs/epoxy composites was mainly attributed to the dielectric loss rather than magnetic loss. The absorption peak frequency of the CNTs/epoxy composites can be controlled by plating CNTs with nickel or by filling Ag nanowire into CNTs.