The carrier effect in the m-aramid fiber/cationic dye/benzyl alcohol system

Studies with benzyl alcohol and other substances (acetophenone, dimethylace tamide, dimethylsulfoxide) interacting with poly(m-phenylene isophthalamide ) fibers have shown that the carrier effect in the dyeing process takes pla ce through a balanced combination of several factors. For a substance actin g as a carrier, the distribution equilibrium must be on the side of the fib er. This is the case if the substance has only a limited hydrophilicity, in dicated by a low solubility of the carrier in the dyeing liquor. In order t o be effective, it is not sufficient that the sorption of the carrier takes place only in the interior of the fiber; it must also take place on the fi ber surface. If the carrier layer on the fiber surface is removed, the dye uptake rate decreases. An optimal carrier effect is accompanied by an incre ase in the degree of crystallinity and changes in the mechanical properties (decreased tensile strength and elongation at break, as well as increased Young's modulus). When combined with the carrier substance, water is also a ble to enhance the dye uptake rate (co-carrier). Electrolytes do not influe nce the sorption of carrier.