The effect of draw ratio on the diffusion of Naphthalene Fast Orange 2GS in nylon 6 has been studied by means of microspectrophotometric (MSP) method.
The diffusion coefficient D (c) of the dye in nylon 6 was found to be strongly dependent on dye concentration in the substrate. This concentration dependence of D (c) decreases with a minimum at the draw ratio of 2, and then increases with the increase of draw ratio.
The diffusion coefficient at zero concentration of dye Do, the apparent diffusion coefficient by Krämer's method _??_ and the amount of dye adsorbed at equilibrium pass through a maximum at the same draw ratio.
The amount of the amino end groups does not change appreciably with drawing.
These results are explained by changes, accompanied by drawing of, the fine structure of nylon 6 and the contribution of non-ionic adsorption in dyeing mechanism.