PENETRATION BEHAVIOR OF DISPERSE DYES INTO MODIFIED POLYESTER FIBERS

The early stage of dyeing of polyester fibres pretreated with various chemical reagents has been thoroughly studied. The rate of disperse dye penetration increases with time and temperature of dyeing. Disperse dyes with relatively high surface hydrophobic properties showed an increased affinity for the fibres. The rate of diffusion decreases as the dipole moment of the dye increases. Increasing the temperature of dyeing progressively influenced the penetrability of a disperse dye with a low dipole moment. The larger the volume of the dye molecule, the lower is the rate of diffusion and also the rate of dyeing. The rate of diffusion is found to be inversely proportional to the steric molecular structure of the dyes. Dyes having low molecular expansions showed higher rates of diffusion into modified polyester fibres.