ζ-POTENTIALS AND DYEING PROPERTIES OF FORMALIZED AND ACID-TREATED FORMALIZED POLY(VINYL ALCOHOL) FIBERS IN AQUEOUS SOLUTIONS OF DIRECT DYE

Abstract

The ζ-potentials and dyeing properties of formalized poly(vinyl alcohol) (PVA) fiber (I) and its acid-treated product (II) in aqueous solutions of a direct dye, Benzopurpurine 4B, have been studied. The ζ-potentials of the fibers were measured by the streaming-potential method. The surface dye adsorption (Ms) of the fibers was calculated from the ζ-potentials obtained and the total dye adsorption (Mt) was determined by the colorimetric method.The negative ζ-potentials and Ms for I and II increased with an increase in the degree of formalization of the fibers. On the other hand, Mt, the surface area (Sa) covered by dye molecules, and the degree of swelling of these fibers decreased with increasing degree of formalization. The negative ζ-potentials and Ms for I were fairly larger than those for II. However, Mt, Sa, and the degree of swelling for the former were considerably smaller than those for the latter.It is apparent that the surface dyeing behavior of I and II with the direct dye is remarkably different from the total dyeing behavior of these fibers.