Research on nano-Sb₂O₃flame retardant in char formation of PBT

Abstract

Modified nano-Sb2O3 could dramatically affect pyrolysis of fire retardant system, and improved the flame-retardant performance. Modified nano-Sb2O3 was prepared by planetary high-energy ball mill and nano-Sb2O3/ (poly butylenes terephthalate) (PBT) composite was prepared by modified Sb2O3 nano particles. Its char formation was studied via transmission electron microscope(TEM), scanning electron microscope(SEM) and Thermo-gravimetric analysis(TGA). Results indicated that nano-Sb2O3 promoted catalytic char formation of PBT effectively. The samples were carbonized at 600°C by muffle furnace and the char yield of PBT composites increased gradually with the increase of flame retardant additives. The highest char yield rate reached 6.785% when the flame retardant was 3.5 wt%, which was 12.36 times as high as that of pure PBT. Char formation could be character by TGA. At 600°C, the char yield rate of pure PBT was about 0.1% while the char yield rate increased to 5.58% when the addition of nano-Sb2O3 flame retardant was 1.5 wt%, and 7.58% when the addition was 5 wt%. The results indicated that nano-Sb2O3 flame retardants crosslinked and catalyzed PBT, promoting degradation and char formation and increasing residual carbon. The residual morphologies of the nano-Sb2O3/PBT composite were investigated through scanning electron microscopy(SEM). Results showed that the nano-Sb2O3 could change the degradation path of PBT and improved char yield and carbon layer density of nano-Sb2O3/PBT composite, which prevented heat transfer from external to internal and insulated heat and oxygen.