Diffusion Kinetics of Orange-II in Nylon 661

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Abstract
The effect of draw ratio on the diffusion kinetics of Orange-II in nylon 66 has been investigated in an infinite dyebath buffered at pH 5.8 at temperatures between 40° and 102° C. Diffusion coefficients were ohtained by applying Hill's equation to the total amount of dye adsorbed as a function of time. As the fiber is drawn, there is very little reduction in the equilibrium adsorption of dye, but the diffusion coefficient is reduced to about one-half its previous value for each integral unit of draw ratio. Activation energy for diffusion increases from about 22 to about 28 kcal/mole as the draw ratio increases from 1.0 to 5.99. The effect of a boiling water pretreatment on the rate of diffusion relative to un treated samples depends upon the temperature at which they are compared. Even though the density increases upon treatment, the rate of diffusion is greater when dyed at 60° but lower when dyed at 102°. The wet treatment lowers the activation energy for diffusion to about 18 kcal/mole, a value which is nearly independent of draw ratio.
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