ABSTRACT Flame retardation has been a vital modification for most polymer materials, especially for the extremely combustible and widely used polystyrene foams in various fields. A synergistic flame‐retardant strategy based on expandable graphite (EG), ammonium hypophosphite (NHP), and sodium polystyrene sulfonate (PSSA) was proposed to manufacture high‐performance fire‐safety expandable polystyrene (EPS) foams with satisfied comprehensive physical and mechanical properties. The influence and working mechanism of EG/NHP/PSSA in inhibiting EPS foam combustibility were studied. The dose‐effect relationship results disclosed the multiple synergistic mechanisms of EG/NHP/PSSA in improving the anti‐ignition, self‐extinguishing, char‐forming capability, and suppressing peak burning intensity of EPS foam. 7EG/11NHP/2PSSA/EPS achieved a LOI value of 31.0%, passed UL94 V‐0 rating without melt dripping, and self‐extinguished within 1 s after two flame applications. The multi‐synergy flame retardant mechanism of EG/NHP/PSSA was also disclosed by combustion process monitoring, char residue investigation, and thermal decomposition tracing, including the suppression on the β‐scission of EPS foam. This study on the synergistic flame‐retardant combination strategy provides new insights for manufacturing high‐performance fire‐safe polymeric foam materials.
Wang et al. (Sun,) studied this question.