SOME EVALUATIONS OF THE DYEING PROPERTIES OF MODIFIED POLYESTER FIBERS

The dyeability of polyester fibres pretreated with various chemical reagents has been thoroughly investigated. Interpretation of the dye molecules diffused into the modified substrate in relation to the dyeing parameters as well as the specific characteristics of both dye molecules and solvent of pretreatment has been undertaken. Pretreatment efficiencies can be indicated in a descending order as 1.4-dixan, N,N-dimethylformamide, cyclohexanone, piperidine, aniline and finally sodium hydroxide. The relative half-dyeing time increased and the relative specific dyeing rate constant decreased with the increase of the dipole moment of the applied dyes. A tendency is also recorded towards a decrease of affinity and heat of dyeing as the dipole moments of the dyes increase. Organic solvent modification of polyester fibres favours the decrease of the degree of randomness in the dyeing process as indicated by a change of entropy.