Synergistic Enhancement of Flame Retardancy and Ceramization Performance in EVA / POE Composites via Aluminum Silicate and Ammonium Polyphosphate Compounding

Ethylene‐vinyl acetate/polyolefin elastomer (EVA/POE) composites are typically characterized by high flammability and poor structural stability at elevated temperatures, which limit their applications in fire‐resistant fields. In this work, ceramifiable flame‐retardant EVA/POE composites were fabricated by incorporating aluminum silicate (AS) and ammonium polyphosphate (APP) with different ratios. The results demonstrate that the AS/APP ratio plays a critical role in determining the comprehensive performance. The optimized composition (S2) exhibits balanced mechanical properties at room temperature, with a tensile strength of 7.12 MPa and an elongation at break of 119.62%. After sintering at 950°C, the ceramic residue shows a high flexural strength of 18.51 MPa, along with reduced porosity and improved structural integrity. In addition, the composite achieves an LOI value of 31.7% and UL‐94 V‐0 rating, and maintains a low back‐surface temperature below 300°C after prolonged flame exposure. The enhanced performance is attributed to the synergistic effects of AS and APP, suggesting a synergistic interaction involving gas‐phase flame retardancy, liquid‐phase‐assisted densification, and ceramic phase evolution. This work provides an effective strategy for designing ceramifiable flame‐retardant polymer composites with balanced mechanical properties and high‐temperature stability.