Synergistic effects of nano-Mn0.4Zn0.6Fe2O4 on intumescent flame-retarded polypropylene

The melamine salt of 5,5-dimethyl-1,3,2-dioxaphosphorinane-2-oxide-2-hydroxide (IFR100) was used as an intumescent flame retardant in flame-retarded polypropylene (PP). As a synergistic agent, nanoMn(0.4)Zn(0.6)Fe(2)O(4) was incorporated into the PP/IFR100 composite at different proportions. The synergistic effects of nano-Mn0.4Zn0.6Fe2O4 were studied by the limiting oxygen index (LOI) test, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The synergistic effect of the nanoMn(0.4)Zn(0.6)Fe(2)O(4) additive with IFR100 was clearly observed by LOI. The TGA results showed that nanoMn(0.4)Zn(0.6)Fe(2)O(4) improved the thermal stability of the PP/IFR100 system above 400 degrees C. On the basis of the FTIR and XRD results, it was evident that nanoMn(0.4)Zn(0.6)Fe(2)O(4) efficiently promoted the formation of a charred layer containing phosphocarbonaceous structures. The SEM micrographs indicated that nanoMn(0.4)Zn(0.6)Fe(2)O(4) strengthened the structure of the char layer remaining after combustion.