Abstract: The intercalated nanocomposites of polystyrene (PS) were prepared by means of direct melt blending of polystyrene and organic montmorillonite (OMMT). The flame-retardant property of the nanocomposites was investigated by employing horizontal burning, oxygen index, thermogravimetry and high temperature treating methods. It was shown that the introduction of OMMT can decrease the horizontal burning speed and improve the oxygen index of the nanocomposites. The thermal stability and flame retardancy of the nanocomposites are enhanced noticeably. It is believed that the shielding and obstructing effects of silicate layer to the transfer of heat, oxygen and degradation products are responsible for the increase of flame retardancy.

Key words: polystyrene, organic montmorillonite, flame retardancy, thermal stability