Some new basic azo-dyes derived from thiadiazole were synthesized to e
valuate the dyeing parameters on polyester fibre (PET) for optimizing
the dyeing process. The kinetics of dyeing were performed at various t
emperatures (80-degrees, 90-degrees and 100-degrees-C) in the absence
and in the presence of phenol, benzoic acid and salicylic acid as carr
iers. Thermodynamic affinities were also measured. The dyeing rate con
stants increase on increasing the concentration of carrier, while low
affinity values were observed for the dyes bearing hydroxyl groups, ow
ing to increased solubility of the dye in the dyebath. This behaviour
is less evident in the dyes bearing a methyl group in the thiadiazole
ring. The dyes show good fastness to light, perspiration and dry clean
ing.