Dyeing Characteristics of Acala Cotton Seed Fibers

Abstract

The dyeing characteristics of fibers from three Acala cotton varieties, i.e., Maxxa, SJ-2, and SJC-9, are investigated using direct and reactive dyestuffs along with the Goldthwait cotton maturity test. Dyed and less-dyed fibers are detached from the dyed seed fibers, separated, and characterized by seed fiber weight, single fiber strength, and color measurement. With Direct Blue 1, SJC-9 fibers are dyed to the darkest shade across all seed fiber weights, whereas the Maxxa fibers have the lightest shade. The SJC-9 seed fibers have the least amounts ( ~5%) of less-dyed fibers and the proportions of such fibers are independent of seed fiber weights. For the Maxxa and SJ-2 varieties, the proportions of less-dyed fibers decrease with increasing seed fiber weights. The proportions of less-dyed Maxxa and SJ-2 fibers are above 30% on seed fibers weighing less than 100 mg and are 10% or less on seeds weighing more than 150 mg. The SJ-2 seed fibers contain higher proportions of less-dyed fibers, but their overall shades are deeper than the Maxxa fibers. For all three varieties, most less-dyed fibers are from the chalazal ends of the seeds of all seed fiber weights. Dyeing with Reactive Blue 19 results in the same proportions of less-dyed fibers on the Maxxa seed fibers as with Direct Blue 1. The Goldthwait cotton maturity test confirms the trend of decreasing amounts of less-dyed fibers with increasing seed fiber weight with both direct and reactive dyes. For all three varieties, the force to break is higher for the dyed fibers than the less-dyed fibers, confirming that less-dyed fibers have less developed cell wall structures.Lack of dyeing uniformity in cotton products has been a long-standing concern of the textile processing industry. Dyeing problems with cotton products are thus far associated with less or undeveloped fibers or with fiber immaturity. These dyeing defects are not evident until after the fabrics have been dyed, and they greatly reduce fabric quality, desirability, and value. Considering the significant impact on product quality, however, literature on efforts to understand and solve these dyeing uniformity problems has been modest [ 2-6, II -18. 201.Most such dyeing defects have been associated with neps, specks, and seed coat fragments [ 1, 11 ) . Discussions of neps date back to 1848 in Clegg and Harland's s [ 5 ] review. Neps have had a number of slightly varying definitions: generally, they are clusters of tangled immature or dead fibers that are predisposed to snarling or clumping because of their thin cellulose cell wall and low resistance to bending. Dyeing defects caused by neps have been categorized into three types [ 18 ] . One type consists of matted fibers that are dyed to a similar depth as the rest of the fabric, but appear lighter because of the higher reflectance of their flat surfaces. Another type consists of immature fibers that fail to dye to the same shade or depth as the remaining fibers. The third type occurs when surface neps are removed after dyeing, leaving white or lighter sp...