Spectroscopic Studies to Evaluate the Interactions between Disperse Azo Dyes and Alcohols

To know the dyeing mechanism of polyester fibers with disperse azo dyes, the contribution of hydrogen bonding between alcohols and the dyes was investigated by the visible absorption spectra using the modified McRae's equation. The formation of hydrogen bonding was confirmed by infrared absorption spectra of the azo dye model-alcohol system in carbon tetrachloride. It was found that alcohols acts as a proton donor and dyes as a proton accepter. The hypsochromic shift of the λmax in alcohols due to hydrogen bonding was found to be 100-500cm-1. The bond energy between ethanol and the dyes was 0.2-1 kcal/mol which wa s about 3-9% of the total dye-ethanol interactions. A very little degree of contribution was found for hydrogen bonding in the interactions between disperse azo dyes and methyl benzoate or poly(ethylene terephthalate) film (PET).