ABSTRACT Protective materials for bridge main cables face a critical challenge in achieving both flame retardancy and aging resistance simultaneously. Conventional materials are prone to structural and functional degradation in complex service environments, which limits their long‐term applicability. Leveraging the intrinsic flame retardancy and weather resistance of chlorosulfonated polyethylene (CSM), this study constructed three distinct flame‐retardant systems based on aluminum hydroxide (Al(OH) 3 ), magnesium hydroxide (Mg(OH) 2 ), and zinc borate (ZB). Three corresponding composites designated ZR‐1, ZR‐2, and ZR‐3 were successfully prepared. The influence of different flame‐retardant mechanisms on microstructure and macroscopic properties was systematically investigated. Results indicated that ZB, owing to its excellent interfacial compatibility and nanoscale dispersion, yielded the composite ZR‐3 with superior mechanical properties. It demonstrated a tensile strength of 19.88 MPa and an elongation at break of 133.48%. Furthermore, ZB promoted the formation of a dense char layer at elevated temperatures, resulting in a residual char yield of 23.02%. In contrast, the Mg(OH) 2 system endowed ZR‐2 with the highest thermal stability, exhibiting a glass transition temperature T g = −35.9°C, and superior UV aging resistance. After UV exposure, tensile strength decreased by only 2.32 MPa, while the limiting oxygen index (LOI) was reduced by merely 0.6%. Notably, in salt spray environments, ZR‐3 exhibited exceptional resistance to chloride ion erosion. This advantage stems from the chemical stability and structural reinforcement imparted by ZB, which resulted in a minimal tensile strength decrease of 1.17 MPa and an LOI reduction of 1.8%. This work elucidates the intrinsic relationship between multi‐mechanism flame retardancy and material durability. It offers novel insights and robust experimental support for developing advanced, adaptive, and long‐life protective materials for bridge cables.
Sun et al. (Mon,) studied this question.