The Carrier Effect in the m-Aramid Fiber/Cationic Dye/Benzyl Alcohol System

Abstract

Studies with benzyl alcohol and other substances (acetophenone, dimethylacetamide, dimethylsulfoxide) interacting with poly( m-phenylene isophthalamide) fibers have shown that the carrier effect in the dyeing process takes place through a balanced combination of several factors. For a substance acting as a carrier, the distribution equilibrium must be on the side of the fiber. This is the case if the substance has only a limited hydrophilicity, indicated by a low solubility of the carrier in the dyeing liquor. In order to 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 fiber surface. If the carrier layer on the fiber surface is removed, the dye uptake rate decreases. An optimal carrier effect is accompanied by an increase 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 able to enhance the dye uptake rate (co-carrier). Electrolytes do not influence the sorption of carrier.