Studies on the temperature dependence of extinction oxygen index values for cellulosic fabrics: III. Comparison with limiting oxygen index for commercial flame‐retarded cotton

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 ṕoor 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, L 0 , and area density‐dependent, L 1 , terms to be determined. Like conventional LOI values, L 0 , values also reduce significantly at elevated temperatures.