Polystyrene-based composites and nanocomposites with reduced brominated-flame retardant

Polystyrene was melt blended with a halogen-based flame retardant (FR), hexabromocyclododecane, and a non-halogenated FR, triphenyl phosphate (TPP), in a twin-screw extruder. An organically modified montmorillonite (Cloisite 15A) was used to prepare FR polystyrene nanocomposites. The flammability properties and thermal stability of FR polystyrene composites and nanocomposites were investigated. X-ray diffraction analysis showed that the exfoliation structure of organically modified montmorillonite in polystyrene nanocomposites may be achieved by melt-compounding in a twin-screw extruder. Furthermore, a good dispersion of FRs and nanoparticles of organically modified montmorillonite was observed by energy dispersive X-ray analysis. Thermogravimetric analysis demonstrated that the thermal stability of FR nanocomposites enhanced in the presence of clay nanoparticles and antioxidant. The aim of this study was to reduce the FR level, especially in the brominated FRs. The good results obtained by the limiting oxygen index test showed high-performance flammability properties in the composites containing hexabromocyclododecane and TPP, resulted from the synergy effects between these two FRs. However, in spite of producing high thermal performance polystyrene nanocomposites and dispersing clay nanoparticles efficiently into the polystyrene matrix, the flame retardancy properties were deteriorated in the presence of clay nanoparticles. Therefore, the organically modified clay (Cloisite 15A) was not a good synergic compound to improve the flame retardancy of polystyrene nanocomposites.