Studies on evolved gases and smoke generated by flame-retarded phosphorylated cellulosics

Abstract Samples of flame-retarded durable cotton fabrics, obtained by converting cotton to cellulose ammonium phosphate (CAP)-metal complexes, were pyrolysed in air in the temperature range 225–375°C. The limiting oxygen index (LOI) values of these fabrics were found to range from 28·5 for the Ni(II) complex to 53·6 for the Cu(II) complex. The evolved gases and smoke were collected in a Stanton-Redcroft FTB accessory which enabled smoke obscurations and percentage concentrations of carbon monoxide and carbon dioxide to be determined. In a separate series of experiments under non-flaming conditions, the Fourier transform infrared spectra obtained for the evolved pyrolysis gases did not show the presence of any gaseous phosphorus species indicating that phosphorus was retained in the condensed phase. Infrared spectra of the char residues did show some evidence for the presence of phosphorus species. Overall the studies showed that, compared to untreated cotton, the CAP-metal complex fabrics yielded less smoke under non-flaming conditions but more carbon monoxide and carbon dioxide under flaming conditions. Thus, the CAP-metal