Synergistic Flame Retardant Effect of Organic Boron Flame Retardant and Aluminum Hydroxide on Polyethylene

This study aimed to develop an organic/inorganic synergistic flame retardant on polyethylene (PE). Hexakis-(4-boronic acid-phenoxy)-cyclophosphazene (CP-6B) was used as organic flame retardant to improve the flame retardant efficiency of aluminum hydroxide (ATH) on PE. The limiting oxygen index (LOI) value of PE/20 %ATH/20 %CP-6B reached 27.0 %, and vertical burning (UL 94) V-0 rating was attained. The peak heat release rate (pk-HRR) of PE/20 %ATH/20 %CP-6B was 33.7 % and 75.5 % of pure PE and PE/40 %ATH, respectively. The flame retardant mechanism of PE composites was also investigated using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), muffle furnace, Fourier transform infrared (FTIR), and Pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS). The results showed that ATH/CP-6B was an efficient flame retardant, which was effective in the gas phase and condensed phase simultaneously. CP-6B improved the flame retardant efficiency of PE/ATH and reduced the effect of ATH on the mechanical properties of PE.