Abstract: In order to improve the flame retardant performance of polybutylenes terephthalate (PBT), an Sb₂O₃/BPS-PBT composite was prepared by means of mechanical ball milling first and then melting injection molding method. The effect of Sb₂O₃ particle size on flame retardancy of PBT-matrix composite was studied and the flame retardant mechanism of the PBT-matrix composite was analyzed. The result showed that Sb₂O₃ would make the initial decomposition temperature of PBT advanced and the thermal decomposition rate slowed down; Adding Sb₂O₃ with the same mass fraction, the efficiency of nano-Sb₂O₃ in the case of gas-phase flame retardance and the catalytic effect of promoting carbon residue formation would be superior to micro-Sb₂O₃; When the mass fraction of bromide of polystyrene (BPS) and nano-Sb₂O₃ were 10% and 5%, respectively, the LOI of the composite would be 28.3% and theUL94 would reach level V-0.

Key words: PBT, Sb₂O₃, particle size, thermal stability, flame-retardant performance