Decoration of basalt fibers with hybrid Fe3O4 microspheres and their microwave absorption application in bisphthalonitrile composites

Abstract

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.