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Based on the surface analysis of carbon fiber, an epoxy resin matrix with good wettability to carbon fibers had been developed and studied, and the influence of winding tension on the interface and mechanical properties of the composite were studied. The surface morphology of carbon fiber and the active functional groups of sizing agent were analyzed. In order to form a good interface combination, the wettability between carbon fibers and epoxy resin matrix was characterized by dynamic contact angle. The winding tension played an important role in the mechanical properties of composites. Therefore, a kind of carbon fiber reinforced composites, Naval Ordnance Laboratory (NOL) rings were fabricated using different winding tensions. Particularly, when the winding tension was 30 N, the interfacial bonding between carbon fibers and resin matrix was the most compact and firm. The tensile strength and interlaminar shear strength (ILSS) of NOL rings reached high values, 2712 MPa and 75 MPa, respectively. [ABSTRACT FROM AUTHOR]

In this study, a magnetic/dielectric composite precursor is obtained by in situ growing zeolitic imidazolate framework-67 nanoparticles on the surface of acidified multi-walled carbon nanotubes (MWCNTs). After pyrolyzing the precursor in an argon atmosphere, a kind of nano-heterogeneous composite wave absorber was prepared. Subsequently, a new type of magnetic/dielectric wave-absorbing composite was prepared by heating and curing Co–C–MWCNTs and epoxy resin, and the properties of the composite were adjusted by changing the content of Co–C–MWCNTs. A variety of modern characterization methods were used to systematically study the micro-morphology, element composition and electromagnetic properties of the composite. The results show that after the combination of MWCNTs and Co–C particles with regular dodecahedron structure, a special synergistic effect appears. The addition of magnetic MOF derivatives not only improves the impedance matching characteristics of the composite and increases the magnetic loss mechanism, but also provides a new path for the transmission of electromagnetic waves because of its special pore structure and the three-dimensional network structure formed by cross-linking with MWCNTs. The interface polarization and multiple scattering effects greatly improve the attenuation efficiency of electromagnetic waves. In X-band (8–12 GHz), the Co–C–MWCNTs/EP composite with a loading of 17.5 wt% can achieve an effective absorption bandwidth of 2.38 GHz when the matching thickness is 1.6 mm. The combination of novel MOF-derived materials and traditional carbon materials is expected to provide new ideas for the design of composites with microwave absorption capabilities. [ABSTRACT FROM AUTHOR]