Thesis Details

Thesis Title: A study of the effects of dye concentration and ratios of dyes in combination on disperse dye exhaustion
Thesis Author: Samuel Graham
Abstract: In today's dyeing industry, an increased number of colors are introduced into dyehouses on a daily basis which makes cycle selection very difficult. When dyeing polyester with disperse dyes, dye cycles to dye new colors are determined from existing cycles having similar dyes and amounts of dyes. Much previous literature discusses basing temperatures for disperse dye exhaustion control on the exhaustion characteristic of each individual dye in the dye formula at hand. Since most color formulas contain more than one dye, determination of how dyes exhaust in combination is needed. Adding to the difficulty of cycle optimization is that several methods exist that are used to study disperse dye exhaustion behavior. The primary objectives of this thesis were to study the effects of concentration and ratios of dyes in combination on disperse dye -exhaustion. A 100% woven polyester fabric was the substrate, and three medium-high energy disperse dyes were used for dyeing. _Five levels of concentration with six different ratios within each concentration level were employed for dyeing. Dye exhaustion was measured by solution transmission, fabric reflectance of swatches removed through the dye cycle, and fabric reflectance of reverse dyed swatches. Oyebath solution samples were dissolved in acetone and water to determine whether a relationship exists between these two techniques for obtaining transmission data. The results of this thesis show that disperse dye exhaustion is dependent on the ratio of each dye in a given mixture, and that as concentration increases the rate of exhaustion decreases. For each ratio studied, the rate of exhaustion decreased as total dye concentration increased. When dyebath samples were measured as dispersions in water, the percent exhaustion data for each dye showed a great deal of variation compared to the same samples that were measured with the dispersions dissolved in acetone. This indicates in-bath monitors measuring disperse dye exhaustion in a water medium may produce erroneous data in some instances. Measuring fabric reflectance of reverse dyed swatches produced very similar results to the solution transmission technique; therefore, this technique could be substituted for solution measurement for obtaining useful information regarding dye exhaustion without the complexity associated with transmission measurements using acetone.