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This article provides an in-depth exploration of the current state of research in microwave-absorbing composite materials, juxtaposing the status quo of coating type and structurally reinforced resin-based composites, with a particular emphasis on the latter's structural and performance superiority. It succinctly elucidates the mechanisms of electromagnetic shielding, as well as the conditions and underlying principles that govern the absorption of microwaves by composite materials. The review continues by dissecting the strategies for enhancing the microwave-absorption capabilities of resin-based composites, including the classification of absorbents, absorbent selection, and an overview of structural design innovations in microwave-absorbing materials. Structural wave-absorbing composites are manufactured by combining different types of resin matrices, absorbers, reinforcing fibers and construction methods. The interactions between these components are scrutinized to reveal how each contributes to the overall performance of the composite. We spotlight the unique construction methods and the intricate relationship between structure and performance in structurally reinforced composites, offering insights into the optimization strategies for composite-material absorption characteristics. Concluding with a forward-looking perspective, the article contemplates the burgeoning potential and future applications of fiber-reinforced resin-based microwave-absorbing composites, setting the stage for a new era in material science and technology.
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With the rapid advancement of intelligent electronics, big data platforms, and other cutting-edge technologies, traditional low dielectric polymer matrix composites are no longer sufficient to satisfy the application requirements of high-end electronic information materials, particularly in the realm of high integration and high-frequency, high-speed electronic communication device manufacturing. Consequently, resin-based composites with exceptional low dielectric properties have garnered unprecedented attention. In recent years, benzoxazine-based composites have piqued the interest of scholars in the fields of high-temperature-resistant, low dielectric electronic materials due to their remarkable attributes such as high strength, high modulus, high heat resistance, low curing shrinkage, low thermal expansion coefficient, and excellent flame retardancy. This article focuses on the design and development of modification of polybenzoxazine based on low dielectric polybenzoxazine modification methods. Studies on manufacturing polybenzoxazine co-polymers and benzoxazine-based nanocomposites have also been reviewed.
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Self-polymerization epoxy/phthalonitrile (APPEN) pre-polymers were studied systematically, and then, gelation time and differential scanning calorimetry (DSC) were employed to investigate their curing behaviors. Taking advantage of orthogonal test analysis, the key factors that affected the co-polymerization of APPEN were defined and the appropriate pre-polymerization conditions were analyzed. A possible curing mechanism of APPEN was proposed. Then, the thermomechanical and mechanical properties of glass-fiber-reinforced APPEN laminates (APPEN/GF) prepared at 180 °C were analyzed to understand the cross-linked and aggregation structures. Fracture surface of the composite laminates was also investigated to reveal the copolymerization degree and the interfacial binding. The results indicated that APPEN/GF composites exhibit outstanding mechanical and thermomechanical properties (flexural strength, 712 MPa, flexural modulus, 38 GPa, and Tg > 185 °C). The thermal stability (T5% > 334 °C and IPDT reached 1482 °C) of APPEN/GF composites was also investigated to further reveal the copolymerization between epoxy resin and aminophthalonitrile, which may be beneficial to the application of epoxy-matrix-based composites in the field of high-performance polymer composites.