Smoke, CO2 and CO Evolution from Cotton and Flame Retarded Cotton: Part 2. Behaviour of Single Layer Fabrics in Air at Elevated Temperatures

Abstract

Smoke, CO and CO₂ emissions have been determined from un treated cotton and flame retarded cotton fabrics at elevated temperatures. The flame retardants studied at commercial levels of applications were ammonium polyphosphate (Amgard TR), ammonium polyphosphate—ammonium bromide (Amgard CD), a phosphonium salt-urea-polycondensate (Proban CC), a phos phono-propionamide (Pyrovatex CP) and an antimony (III) oxide-aliphatic bro mide (Flacavon H14/587) formulation. Combustion product analyses were undertaken at elevated temperatures (225-300°C) in air under burning conditions (above the respective temperature oxygen index) and non-flaming pyrolysis. Under both conditions smoke densi ties and CO concentrations increased with temperature. Carbon dioxide con centrations under non-flaming conditions showed similar increases but under burning conditions, decreased with increasing temperature. At a given temper ature, the P- and N-containing retardants reduced smoke density under burn ing conditions and increased it under pyrolysis relative to pure cotton below 350°C. These same flame retardants reduced CO and CO₂ formation at each temperature from burning fabrics but produced little change with respect to cotton under non-flaming conditions. The presence of aliphatic bromine in the Sb₂O₃—bromine synergistic system caused significant increases in smoke density and CO and CO₂ concentrations with respect to all other fabrics under pyrolysis in air. The observed trends are analysed in terms of current knowledge of pyrolysis and combustion mechanisms.