Decoration of basalt fibers with hybrid Fe3O4microspheres and their microwave absorption application in bisphthalonitrile composites

To develop high performances of inorganic fibers/polymer composites, the interfacial interaction and dispersal of fibers are the two essential issues to be considered. Herein, we report the surface decoration of basalt fibers (BF) with hybrid Fe3O4 microspheres (FePc–Fe3O4) and their microwave absorption application in bisphthalonitrile composites was systematically investigated. Firstly, the hybrid Fe3O4 microspheres with a diameter of ∼140 nm were self-assembled onto the basalt fibers via a simple solvothermal route, as confirmed by SEM and TEM observations. The obtained BF (FePc–Fe3O4–BF) displayed magnetic performance with excellent interfacial adhesion application. Secondly, the FePc–Fe3O4–BF reinforced bisphthalonitrile composite laminates were studied for improvement in their microwave absorption, mechanical and thermal properties through strategically incorporating the FePc–Fe3O4 microwave absorber at the fiber/fabric–matrix interfaces. The calculated reflection losses showed that the best microwave absorption reached −31.1 dB at 5.9 GHz with a matching thickness of 5 mm. The results indicated that investigation of the decoration of basalt fibers and the addition of a special microwave absorber opened up a new route to develop the composite laminate as a promising candidate for microwave absorbing materials in high-temperature applications. Besides, we found that the FePc–Fe3O4–BF reinforced bisphthalonitrile composite laminate, with excellent thermal stability, revealed an approximately 189% increase in flexural strength and also offers better microwave absorption compared to that of the BF reinforced bisphthalonitrile composite laminate.