A facile and efficient flame-retardant and smoke-suppressant resin coating for expanded polystyrene foams

Abstract

Flame-retardant and smoke-suppressant expanded polystyrene (EPS) foams were prepared by coating a mixture of thermoplastic phenolic resin (PF) and aluminum hypophosphite (AP) or expandable graphene (EG) onto EPS spheres. The PF reacting with AP by hydrogen-bond interaction formed a facile flame-retardant coating PF/AP, which not only greatly reduced flammability and smoke release, but also remained the thermal conductivities of EPS foams at low level. Compared with those of EPS/PF/EG, EPS/PF/AP could pass the UL-94 test and showed better flame-retardant performances with lower heat release rates and fire growth rates. Especially, the time to ignition (TTI) of EPS/PF/AP achieved 52 s, much higher than those of EPS/PF/EG (9 s) and neat EPS (2 s). Also, the peak of smoke production rate (PSPR) and the total smoke production (TSP) of both composites were significantly reduced, showing an excellent smoke-suppressant performance. The mechanism analysis suggested that the PF/AP coating could form a compact P–O–C cross-linked char layer and effectively protect the matrix from further combusting. Particularly, the EPS/PF/AP had a higher compressive strength and lower thermal conductivity in comparison with EPS/PF/EG. These above results show that the EPS/PF/AP composite has enormous potential in building thermal insulation field.