In Situ Formation of a Dual Cross-Linking Network in EPDM-Based Composite Rubbers with Sufficiently Low Compression Set for Fireproof Sealing Applications in New Energy Vehicles

The effects of zinc dimethacrylate (ZDMA), serving as a modifier, on the mechanical, thermal, and flame-retardant properties of ethylene-propylene-diene rubber (EPDM) composite materials were investigated. The incorporation of ZDMA effectively introduced Zn²⁺ ions into the composite rubbers, resulting in the formation of a dual cross-linking network that significantly bolstered both the tensile strength and tear resistance of the composite rubbers. Meanwhile, the addition of ZDMA optimized the compatibility between flame retardant ammonium polyphosphate (APP) and the EPDM matrix, giving rise to a synergistic flame retardant effect that maximized the flame retardant performance of the composite rubber. Furthermore, ZDMA contributed to improving the aging resistance of the material, resulting in a remarkably low compression deformation rate (CDR). Notably, the inclusion of ZDMA elevated the limiting oxygen index (LOI) value of the EPDM composite rubbers to 34%, thereby achieving a V-0 flame retardancy classification. This research holds profound implications for the preparation and application of EPDM composite materials, especially in their utilization as sealing materials especially in energy vehicles.