The flame retardant effect of aluminum phosphinate in combination with zinc borate, borophosphate, and nanoclay in polyamide-6

The effect of zinc borate (ZnB), borophosphate (BPO4), and organoclay were studied to improve the flame retardancy of polyamide-6 composites containing organic phosphinates. The flame retardancy of polyamide-6 composites was investigated using limiting oxygen index (LOI), Underwriters Laboratories (UL-94) standard, thermogravimetric analysis, Fourier transform infrared spectroscopy, and mass loss calorimeter. The addition of 15wt% aluminum phosphinate (AlPi) increased the LOI value from 22.5 to 29.5, and V0 rating was obtained from UL-94 test. The addition of organoclay, ZnB, and borophosphate does not change the predominant gas phase mechanism of AlPi during LOI and UL-94 tests. The addition of organoclay increased the condensed phase mechanism of AlPi physically by the protective effect of layered silicate, whereas the addition of ZnB increased the condensed phase mechanism of AlPi chemically by the formation of boron aluminum phosphate species deducted from mass loss calorimeter studies. Copyright (c) 2012 John Wiley & Sons, Ltd.