Research on nano-Sb2O3 flame retardant in char formation of PBT

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 degrees 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 3.5wt%, which was 12.36times as high as that of pure PBT. Char formation could be character by TGA. At 600 degrees 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 1.5wt%, and 7.58% when the addition was 5wt%. 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.