Adsorption behaviour of azo disperse dyes on polyurethane fibre

Adsorption isotherms of disperse dyes were measured and the surfaces of dyed polyurethane, cellulose diacetate and polylactic acid fibres were observed using a scanning electron microscope and compared. Obvious crystal growth of the dyes occurred on the surface of the polyurethane fibres. The maximum dye uptake on polyurethane fibres and the degree of crystal growth varied greatly with the dye type. Factors such as the dye affinity for the fibre, crystallisation properties and dye solubility in the dyebath affect the sorbed state of the dye on the fibre surface. A mechanism is proposed for crystal formation on the fibre surface during dyeing of polyurethane fibre with disperse dyes.