Synchronously improved dielectric and mechanical properties of wave-transparent laminated composites combined with outstanding thermal stability by incorporating iysozyme/POSS functionalized PBO fibers

Modified bisphenol A dicyanate ester (m-BADCy) wave-transparent laminated composites reinforced with functionalized poly(p-phenylene-2,6-benzobisoxazole) (f-PBO) fibers were fabricated using an optimized method of impregnation-winding followed by lamination-molding. m-BADCy was synthesized from copolymerization between (2-((3-trifluoromethyl)phenoxy)methyl)oxirane and the BADCy matrix. f-PBO fibers were obtained by modifying with lysozyme followed by polyhedral oligomericsilsesquioxane (POSS). Lysozyme was coated on the surface of PBO fibers (PBO@lysozyme) and polyhedral oligomericsilsesquioxane (POSS) was grafted onto the PBO@lysozyme fibers (POSS-g-PBO@lysozyme, f-PBO fibers). The dielectric constant (ϵ), 2.81, and dielectric loss (tanδ), 0.0028, for f-PBO fiber/m-BADCy wave-transparent laminated composites were lower than those of PBO fiber/m-BADCy wave-transparent laminated composites (ϵ = 2.91 and tanδ = 0.0043). The interlaminar shear strength (ILSS) and the flexural strength of the f-PBO fiber/m-BADCy wave-transparent laminated composites were significantly increased to 47.6 and 805.8 MPa, increased by 23.0% and 33.5% in comparison to those of PBO fiber/m-BADCy wave-transparent laminated composites (ILSS = 38.7 MPa and flexural strength = 603.5 MPa), respectively. In addition, the corresponding heat resistance index (T_HRI, representing thermal stability) and glass transition temperature (T_g) of the f-PBO fiber/m-BADCy wave-transparent laminated composites were 228.3 and 252.1 °C, respectively.