Synergistic Flame Retardant Effect of Organic Phosphorus-Nitrogen and Inorganic Boron Flame Retardant on Polyethylene

In this study, to develop an organic/inorganic synergistic flame retardant, organic phosphorus-nitrogen flame retardant 6,6-(((sulfonylbis(4,1-phenylene)) bis(azanediyl))bis(thiophen-2-ylmethylene))bis(6H-dibenzo[c,e][1,2]oxaphosphinine 6-oxide (DOPO-N) and inorganic boron flame retardant zinc borate (ZB) were selected. The flame retardant properties of polyethylene (PE) containing ZB/DOPO-N were investigated. PE/20%ZB/10%DOPO-N had better thermal stability and flame retardant properties. The limiting oxygen index of PE/20%ZB/10%DOPO-N reached 24.6%, and UL 94 V-0 rating was attained. The peak heat release rate, total heat release, average effective heat combustion, and fire growth index of PE/20%ZB/10%DOPO-N were lower than when ZB and DOPO-N were added separately. In addition, the flame retardant mechanism was investigated using scanning electron microscopy, X-ray diffraction, energy dispersive X-ray, and Fourier transform infrared spectroscopy. ZB/DOPO-N simultaneously exerted condensed phase and gas phase flame retardant effect. POLYM. ENG. SCI., 2019. (c) 2019 Society of Plastics Engineers