Dissolution of Polyfunctional Reactive Dyed Cotton in Cadoxen Solvent

Abstract

<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:"times="" roman";mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">The kinetics of dissolution of polyfunctional reactive dyeings has been studied and found to be different from that of bifunctional reactive dyeings. For cotton dyed with polyfunctional reactive dyes, the initial faster rate of dissolution was followed by an extremely slow rate and the samples did not dissolve completely even after 24 hr. The initial rate of dissolution of cotton dyed with bifunctional reactive dyes was very slow and was followed by a higher rate and completes dissolution in 24 hr. In the case of polyfunctional dyeings, the activation energy at the faster rate of dissolution was 7-8 kcal/mole, suggesting that the disruption of hydrogen bond is the governing factor for dissolving the non crosslinked fraction. At the extremely slow rate of dissolution, activation energy was 19-20 kcal/mole, which is similar to that for bifunctional dyeings, indicating that dissolution involves disruption of crosslinks. The difference in the behaviours of poly- and bifunctional reactive dyeings has been explained on the basis of higher alkali stability of the dye-fibre bond and the larger size of crosslinks in the former case. The method of application of dyes has also been found to have an effect on the extent of dissolution, as it influences the state of swelling of the fibre at the time of formation of crosslinks.</span>