Synergistic effects in the pyrolysis of phosphorus-based flame-retardants: The role of Si- and N-based compounds

The modification of cotton fabrics with phosphorus-based flame-retardants (FRs) in the presence of synergistic elements such as nitrogen or silicon is reported. For these purposes, analyses of the combustion behavior and the thermal-oxidative stability of the modified fabrics were performed using pyrolyzis - gas chromatography-mass spectrometry (Py-GC/MS), thermogravimetric analysis coupled to Fourier-transform infrared spectroscopy and attenuated total reflection infrared spectroscopy (ATR-IR). It was found that limiting oxygen index (LOI) values were higher in case a P/N/Si instead of a P/N element combination was used. With the former, increased residual masses were obtained and the amount of phosphorus could be reduced by the presence of silicon. The results obtained path the way for further developments and optimizations of flame-retardants by determining the optimum element combinations and element/element ratios, ultimately leading to high flame retardant effects.