The kinetics and thermodynamics of nylon 6 fiber dyeing with hydrogen peroxide-glyoxal redox system

Investigations were focused on the kinetics and thermodynamics of nylon 6 f iber dyeing with the hydrogen peroxide-glyoxal redox system. We tried to un derstand thoroughly the difference between the new redox and the convention al dyeing system, since the mechanism of redox dyeing is a combination of f ree radical and ionic dyeing, whereas the conventional system is only ionic . The study consisted of measuring the dyeing transition temperature (T-D), diffusion coefficient (D-T), activation energies of diffusion, dyeing affi nity, and the dyeing enthalpy and entropy. From the experimental results, t he dyeing transition temperature (T-D) in the redox system is lower than th at in the conventional system. But the diffusion coefficient (D-T) in the r edox dyeing is larger than that in the conventional dyeing. The dyeing affi nity of the free radical dyeing type (redox) is lower than that of the ioni c type (conventional). Moreover, from the analysis of thermodynamics of dye ing, the enthalpy is found to be positive (endothermal reaction) in the red ox system, but it is negative (exothermal reaction) in the conventional one . The entropy is also found to behave similarly, i.e, positive in the redox system, but negative in the conventional dyeing. Finally, the dyeing satur ation value in the redox dyeing system is found to be higher than that in c onventional dyeing. (C) 2000 John Wiley & Sons, Inc.