Porosity Versus Segment Mobility in Dye Diffusion Kinetics— A Differential Treatment: Dyeing of Acrylic Fibers

Abstract

The diffusion kinetics of the cationic dye thionine from an aqueous buffer solution into the two acrylic fibers Dralon X-100 and Dunova was studied at various temper atures between 59.0°C and 98.5 °C. The two fibers are practically identical with respect to chemical composition. The glass transition temperatures in the dry state (Tg) and in water (TD) are the same within experimental error. They differ physically, however, with respect to overall porosity and pore size distribution. The evaluation of diffusion kinetics as a function of temperature and their comparison with the temperature dependence of free diffusion in water, as well as desorption experiments, demonstrate that the pore model mechanism and the free volume (segment mobility) mechanism operate simultaneously. The first is dominant for the porous fiber Dunova and the second for the less porous fiber Dralon.