Abstract
Limiting oxygen index values of single and multilayer Proban CC- and Pyrovatex CP-flame retardant finished cotton fabrics having a variety of area densities were determined as a function of igniter application time and temperatures up to 200°C. Except for the lightweight (140 g m−3) Proban CC-treated fabrics, LOI, like comparable extinction oxygen index (EOI) values, increased as ignition times were increased from 2 to 10 s. Extrapolation to zero ignition time enabled [LOI]0 values to be determined at each temperature, which, for a given flame retardant, increased linearly with area density of mono- and multilayered fabric combinations. Comparison with earlier extinction oxygen index results showed that this [LOI]0 vs. area density dependence had significantly lower correlation than that for [EOI]0. These poor former correlations further substantiated the claims that the EOI concept offers a more effective means of quantifying textile fabric flammability. Analysis of the linear relationships enabled intrinsic limiting oxygen index, L0, and area density-dependent, L1, terms to be determined. Like conventional LOI values, L0, values also reduce significantly at elevated temperatures.