Improving Fire Safety and High‐Temperature Stability of EVA Composites Through Ceramification

ABSTRACT

Ceramizable polymers offer exceptional structural stability and fire safety for high‐temperature applications. This study presents a highly flame‐retardant ethylene‐vinyl acetate copolymer (EVA) composite, engineered through the synergistic incorporation of wollastonite fiber (WF), layered zirconium phosphate (ZrP), and a glass powder/mica filler. While the control composite exhibited severe melt spreading, the synergistic system maintained robust structural integrity at 1000°C. X‐ray diffraction (XRD) revealed that WF and ZrP altered the ceramization behavior, generating stable crystalline phases, including anorthite, an apatite‐type calcium phosphate phase, and monoclinic ZrO ₂ . During 50 kW/m ² combustion tests, the optimized composite demonstrated outstanding fire retardancy and smoke suppression. Compared to the control, it prolonged the time to ignition (TTI) by 325% and reduced the peak heat release rate (PHRR) by 75.8%, total heat release (THR) by 39.8%, peak smoke production rate (PSPR) by 67.5%, and total smoke production (TSP) by 31.1%. Mechanistically, WF and ZrP promote early matrix cross‐linking and ceramification, accelerating the formation of a multiphase ceramic structure. This yields a stable inorganic network reinforced by KZr ₂ (PO ₄ ) ₃ , which acts as a dense thermal and mass barrier in the condensed phase. Ultimately, this work provides valuable insights for designing advanced, high‐temperature‐resistant polymers.