Dyeing Properties of Cotton Fibres Treated with Liquid Ammonia

Both scoured and sodium hydroxide mercerised cotton fibres have been treated with liquid ammonia at -33.4 ºC using commercial operating equipment and then the ammonia removed at 130 ºC in a hot drum. The moisture regain and water absorbency of the fibres treated with liquid ammonia were increased compared with values on untreated fibres, whereas both these parameters on mercerised cotton fibres were decreased by subsequent liquid ammonia treatment. The fibres were dyed with C.I. Direct Red 2 and C.I. Direct Blue 1. Liquid ammonia treatment of the scoured cotton fibres increased the rate of dyeing, equilibrium dye adsorption, standard affinity, heat of dyeing and change of entropy, while the dyeing properties of mercerised cotton were adversely affected by subsequent liquid ammonia treatment