Absorption Spectroscopic Studies on Interaction between Disperse Azo Dyes and Poly(ethylene terephthalate) Film An Estimation of the Interaction from Modified McRae's Equation

In order to obtain information on the dyeing mechanism of polyester fibers with disperse dyes, interactions between poly(ethylene terephthalate) film (PET) and disperse azo dyes have been investigated by the analysis of visible absorption spectra in terms of a modified McRae's equation. From the results, a more real estimation of the interactions was obtained. The following disperse azo dyes were used: The wavenumber shifts of the absorption maxima of the dyes in dyeing PET were measured. A linear relationship was obtained between the calculated and observed frequency shifts. The dipole-dipole force of the azo dyes estimated from the equation was 0.2-O.5kcal/mol and/or 2-3% of the total dye-PET interaction. The sum of the dispersion and induction force of the azo, dyes estimated from the equation was 9-15 kcal/mol and/or 97-98% of the total dye-PET interaction. It appears that the dispersion force ma kes a considerable part of contribution to the dye-PET interaction, and dipole-dipole force and induction force make a much smaller contribution to the interaction.