Interaction of Flame-Retardant and Untreated Cotton Fabrics during Burning

Transfer of flame retardancy from fabric treated with THPOH-NH 3 to untreated cotton fabric during burning was observed on fabric samples sewed together with glass thread. The transfer effect was evidenced by the development of substantial char and the presence of phosphorus and nitrogen in the char of the untreated fabric. Oxygen-index determinations on multilayered combinations of flame-retarded (FR) and untreated fabrics also supported this observation. The extent of FR transfer varied with the geometrical configuration of the layers and the FR add-on. Tests showed that smoke from combustion of THPOH-NH 3 -treated fabric, passed through untreated cotton fabric, was the means of transfer of phosphorus, nitrogen, and flame retardancy. The FR transfer effect was also demonstrated for several other phosphorus-containing flame-retardancy treatments.