Fabrication of Fly Ash-Based Mesoporous Aluminosilicate Oxides Loaded with Zinc and its Synergistic Fire Resistancy in Polypropylene

A kind of mesoporous aluminosilicate oxides (MAOs) were fabricated from industrial waste, coal fly ash. After loaded with zinc on MAO, the product MAO-Zn was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy (SEM). MAO-Zn was incorporated with intumescent flame retardant (IFR) together and used in polypropylene (PP). Basic characterization including limiting oxygen index (LOI), vertical burning test (UL-94), and cone calorimeter test (CCT) were finished. The result showed the LOI value of PP was only 17.7 and cannot pass UL-94 grade; however, 25 wt% IFR in PP help the composite obtained LOI value of 27.6 and passed UL-94V-1 grade. Surprisingly, with only 2 wt% MAO-Zn substitution of IFR, the LOI of PP/IFR composite sharply went up to 37.2 and passed V-0 grade. CCT results documented that heat, smoke, and fatal gas release were obviously suppressed by IFR/MAO-Zn combination. By SEM observation and quantitative analysis of TGA results, the contribution of MAO-Zn was summarized as adsorption of heat/smoke and promotion on charring. It was worth mentioning that the low dose of MAO-Zn (≤ 3 wt%) did not bring further deterioration on mechanical properties