Influence of laundering on durable flame retarded cotton fabrics — Part 1. Effect of oxidant concentration and detergent type

Cotton fabrics flame retarded with tetrakis (hydroxymethyl phosphonium chloride (THPC)-urea-ammonia polycondensate (Proban CC, Albright and Wilson Ltd., U.K.) have been subjected to up to 50 simulated hos pital wash cycles. Laundering variables include sodium perborate oxidant con centration, detergent type (liquid with no oxidant, powder with zeolite and sodium perborate and powder with polyphosphate and carbonate and per borate) and water hardness. The flame retardant system resisted all laundering systems in terms of the constancy of burning behaviour assessed by vertical strip (BS 5438) and limiting oxygen index (LOI) measurements. However, increased perborate con centration changed the thermogravimetric (TGA) response of laundered fabrics. Soft water washing promoted cotton fibre fibrillation independent of deter gent type; increased oxidant concentration promoted secondary wall damage. Hard water washing severely damaged fibre secondary walls and significant depositions of calcium ions often as phosphate occurred on fabric. Presence of the flame retardant was observed to have a stabilising fibrillar binding effect which was offset by a secondary wall crack promoting character