Abstract: Master batch of micro-capsulated red phosphorus (MRP) and polyphenylene oxide (PPO) were compounded forming a flame retardant, which was applied in high impact polystyrene (HIPS) via melt blending. The flame retardant effect was studied through oxygen index, vertical burning test, and thermal gravimetric analysis (TGA). Residue collected during TGA was characterized by Fourier transform infrared spectroscopy (FT-IR). It was revealed that the compound flame retardant, When the contents of MRP and PPO were 10 and 18wt%, respectively, HIPS displayed an oxygen index of 34% and a vertical burning level of FV-0 (1.5mm). There was a synergetic effect between MRP master batch and PPO, and the flame retard acted mainly in the condensed phase.

Key words: high impact polystyrene, halogen-free retardant, flame retardancy, micro-capsulated red phosphorus, polyphenylene oxide, synergistic retarding