Desorption Kinetics of Hydrolyzed Reactive Dyes in Continuous Wash Ranges
Continuous wash ranges clear hydrolyzed reactive dye by maximizing thermal diffusion and maintaining steep counter-current concentration gradients across wash stages.
Cellulosic Fiber Diffusion
Molecular Migration
Physical migration into a polymer matrix occurs when solutes move from the dye liquor to the interior of cotton or rayon fibers. This cellulosic fiber diffusion determines the rate at which dyes penetrate the substrate during the exhaust cycle.
Internal Transport
Penetration begins at the fiber surface where the dye molecule overcomes the electrical charge of the cellulose. As cellulosic fiber diffusion progresses, the concentration within the amorphous regions of the fiber increases. The process slows when the internal concentration approaches the level of the external bath, signifying that the system has reached a steady state where no further net movement occurs.
Mechanical agitation assists the initial contact but the internal migration relies entirely on the concentration gradient established between the liquor and the fiber core.
Thermal Influence
Heat provides the kinetic energy required for molecules to navigate the polymer chains. High temperatures increase cellulosic fiber diffusion by expanding the spaces between cellulose chains.
Production Checkpoint
Mills verify the uniformity of the color through cross-sectional microscopy of individual fibers. Incomplete cellulosic fiber diffusion appears as a ring-dyed effect where the fiber core remains pale. This result often leads to poor abrasion resistance during garment washing.