Effects of oily contamination and decontamination on combustion and flame resistance of thermal protective textiles

Three studies were conducted to determine the effects of contamination and decontamination on combustion and flame resistance of thermal protective textiles. The first study determined the quantity and distribution of oily contaminants in three different FR fabrics after contamination and decontamination using radiotracer analysis and scanning electron microscopy. The second study used thermogravimetry and calorimetry to characterize the combustion process of FR fabrics in terms of thermal decomposition and heat release, before and after contamination with oil and after decontamination. The third study determined the flame resistance and limiting oxygen index of the fabrics before and after contamination and after decontamination. Experimental variables were presence of contamination, fabric type, laundry treatment and number of contamination/decontamination cycles.;Laundering without detergent or pre-wash product resulted in more residual oil and higher flammability and heat release than other treatments. Pre-wash product alone was effective in removing oily contaminants, but resulted in higher flammability and heat release in FR cotton/nylon due to the accumulation of residue. More residual oil and higher flammability and heat release were also noted after five contamination/decontamination cycles than after one for aramid and FR cotton/nylon. Aramid retained less oil and its flammability increased the least with contamination. FR cotton/nylon retained the most oil after decontamination, but still had better flame resistance than aramid. Oil initially penetrated to the interior of cotton fibres making it difficult to remove but less accessible to the flame. FR cotton/nylon had the highest and aramid the lowest heat release whether uncontaminated, contaminated or decontaminated. Flammability of aramid and FR cotton/nylon increases and that of aramid/FR viscose decreases, while heat release from all FR fabrics increases with increased retention of oily contaminants.;Oily contaminants affect initiation of thermal degradation of FR fabrics and formation of char. Aramid and FR cotton/nylon decomposed at higher temperature in the presence of oil unlike aramid/FR viscose. Up to an optimum quantity of oil, a reaction between oil and the flame retardant in viscose alters the thermal decomposition rates and formation of char, and thereby increases the effectiveness of the flame retardant in viscose. Otherwise, contaminated FR fabrics had higher flammability and heat release than did uncontaminated ones.