The Synergistic Effect of Organic Phosphorous/α-Zirconium Phosphate on Flame-Retardant Poly(lactic acid) Fiber

The flame-retardant poly(lactic acid) (FR-PLA) fibers with different contents of modified alpha-zirconium phosphate (alpha-ZrP) and polysulfonyldiphenylene phenyl phosphonate (OP) were prepared by melt spinning. The organic modification of alpha-ZrP was characterized by Fourier transform infrared spectroscopy, wide angle X-ray diffraction, and thermo gravimetric analysis. The limiting oxygen index, vertical burning test, and cone calorimeter test were used to investigate the synergistic effect of OP/alpha-ZrP on flame-retardant property of FR-PLA, the test results suggested that the combustion of PLA fibers was efficiently inhibited by OP/alpha-ZrP. The results of scanning electron microscopy, Raman spectrum, and X-ray photoelectron spectroscopy indicated that the flame-retardant mechanism of OP/alpha-ZrP mainly depended on condensed phase. The tensile strength and morphology of FR-PLA fibers with OP/alpha-ZrP were better than those of fibers treated only with OP, demonstrating that alpha-ZrP could significantly improve the mechanical property of FR-PLA fibers.