Tailoring dielectric and mechanical properties of hollow glass microspheres-modified quartz fiber/hyperbranched polyetherketoneketone laminated composites

Quartz fiber (QF)-reinforced polyetherketoneketone (PEKK) composites demonstrate exceptional potential as wave-transparent materials owing to their outstanding dielectric properties. However, the inherent high melting point and poor solubility of linear PEKK limit its processability in complex structures. To overcome these limitations, a hyperbranched polyetherketoneketone (ST-PEKK) was introduced to improve resin solubility and melt flowability. The QF/ST-PEKK laminated composites were then fabricated through a solution impregnation followed by hot-pressing process. Hollow glass microspheres (HGM) were incorporated at different weight fractions to evaluate their effects on X-band dielectric constant, dielectric loss, interlaminar shear strength, and flexural strength. Remarkably, at 27 wt% HGM, the composite showed a dielectric constant of 2.933 and a loss tangent of 0.0040 while retaining excellent mechanical performance. This study offers theoretical understanding and practical strategies for developing high-performance radomes and advanced electromagnetic structural materials.