Plasma-Engineered Poly(ether ether ketone) Fibers and Flame Retardants for High-Performance Epoxy Composites

Abstract Recently, cloud computing and high-density data centers have intensified thermal management and fire safety challenges, creating a need for multifunctional EP composites with reliable thermal, electrical, mechanical, and flame-retardant performance. Inspired by the hierarchical fiber structure and strong interfacial interactions of natural bamboo, this work first synthesized poly(ether ether ketone) and functionalized its surface by depositing silica via plasma-enhanced chemical vapor deposition, followed by blending with flame-retardant fillers and incorporation into the epoxy system. The obtained composite achieves a limiting oxygen index of 43.7% and a thermal conductivity of 0.312 W·m–1·K–1, representing a 57% increase over pure EP. At 80 °C, the breakdown field strength of the composite still reaches 44.9 kV/mm, while the tensile and flexural strengths remain at 70 and 120 MPa, respectively, demonstrating excellent high-temperature stability. Combined thermogravimetric-infrared and cone calorimeter analyses indicate that this composite system reduces heat and smoke release, promotes the formation of a continuous, dense, and stable char layer, and thereby achieves synergistic flame-retardant effects through the combined effects of condensed-phase protection and gas-phase combustion suppression. These findings provide a useful basis for designing highly reliable epoxy composites for high-power electronic and electrical applications.