3.4. Standard affinity
The data for dyeing equilibrium are generally reported as
the standard affinity of dyeing, Dm [29]. As mentioned
above, the dyeability of cationised cotton is mainly attributed
to ioneion interactions between the negative carboxylate anions
and the positive cationic amino groups present in the cationised
cellulose macromolecules. This dyeing mechanism is
similar to that of dyeing wool with lac dye as reported previously
[15]. Therefore, the standard affinity can be calculated
using Eq. (7):