Synthesis of P-N-Si synergistic flame retardant based on a cyclodiphosphazane derivative for use on cotton fabric

A durable and effective flame retardant (FR) was synthesized in this work by taking advantage of the high reactivity of a cyclodiphosphazane derivative, without the use of formaldehyde. The FR is halogen-free andhas the synergistic effect of phosphorus, nitrogen and silicon. Fire resistance of the cotton fabrics is significantly enhanced after the FR treatment. The limiting oxygen indices of cotton treated with 30% FR increase from 18.2 to 52.9% and decrease to 27.2% after 50 launder cycles, demonstrating that the proposed material is a durable FR. The thermo-gravimetric analysis results indicate that compared with the control cotton, the degradation process of the treated cotton occurred at a lower temperature range, the degree of degradation was lower, and the residue is improved. The total heat release and the effective heat combustion values are notably lower for the treated cotton than the control cotton. Furthermore, mechanical property tests demonstrate that the tensile strength is largely retained, while the bending length of the treated cotton partly increases. The surface morphology of the treated cotton is investigated with scanning electron microscopy. Fourier transform infrared and elemental analysis show that the FR was successfully grafted onto the surface of the cotton fabric. H-1, C-13, and P-31 nuclear magnetic resonance verify the chemical structure of the FR. [GRAPHICS] .