Abstract: PS resin, organically modified montmorillonite (OMMT), and surface modified magnesium hydroxide (MH) were melt blended forming a composite. The structure of the composites was analyzed using X-ray diffraction. The flame-retardant property of the composites was investigated by employing horizontal burning, oxygen index, and high temperature treatment. It was found that the interlayer space of OMMT was increased from 1.46 nm to 3.30 nm after melt blending with PS, indicating a structure of intercalation occurred. The introduction of MH did not affect the formation of the intercalation structure. The coexistence of OMMT and MH decreased the melt dripping and smoke emitting of the composites during burning. The PS/MH/OMMT composite exhibited better stability and flame retardancy than its PS/MH counterpart. As a result, the amount of flame retardants could be greatly decreased.

Key words: polystyrene, magnesium hydroxide, organically modified montmorillonite, synergistic effect, flame retardancy