| Abstract: | Cotton sateen fabric was found to react with the 1 : 2 adduct of phosphorus trichloride and N,N-dimethylformamide (DMF) in DMF or DMF—chloroform solutions at room temperature. During this reaction, the fabric acquired flame resistance. The introduction of as little as 1.2% phospohorus and 0.4% nitrogen, achieved at adduct concentrations as low as 2–5% in reaction times of 5–30 min, was sufficient to impart a useful level of flame retardancy. The effect of the adduct concentration, reaction time, and wash procedures on the flame resistance and other properties of the resultant cotton fabrics was studied. Moderate increases in the wet and dry wrinkle recovery were imparted by the treatment, but the use of high concentrations of adduct were somewhat detrimental to the tensile strength of the fabric. However, adduct concentrations of 20–25% produced a rather durable finish which passed the standard vertical flame test after 20 home launderings. Gradual loss of flame resistance during repeated laundering is attributable to ion exchange properties gradually acquired by the fabric. Based on analytical and in frared spectral data, the initial reaction of cellulose with the PCl3—DMF adduct is thought to involve elimination of one mole of DMF to form cellulose? O? P linkages, as well as some cellulose crosslinking via a second formimidate group of the adduct. Gradual hydrolysis during multiple launderings apparently yields cellulose acid phosphates responsible for the calcium ion uptake and decrease in flame resistance. |
