Thesis Details

Thesis Title: The effect of disperse dyeing in the alkaline pH range on the reduction of oligomer deposition during package dyeing of textured polyester
Thesis Author: Walter Railey
Abstract: Polyester yarn has become the most used synthetic fiber in the world since the end of World War II. For the textile producer, the challenges of manufacturing products from polyester have likewise gained in significance. The use of package dyed polyester yarns is a method for the textile producer to increase flexibility and diversity in areas of fabric formation. Package dyeing of polyester with disperse dyes in an acidic medium presents several problems to the dyer. Low molecular weight polymer, called oligomer, is released into the dyebath when polyester is dyed. These oligomers can deposit on the yarn or the surface of the dyeing machinery. Oligomers on the yarn surface can cause problems in fabric formation. Oligomer deposits in dyeing machinery result in lost productivity due to the time required to clean the machines with alkaline chemicals. This study investigated the effects of the alkaline dyeing of polyester as an alternative to the traditional acidic dyeing process. Specifically, the effects of package dyeing 100 % textured polyester in an alkaline buffer system at two buffer concentrations, two dye cycle times, and with four disperse dyes were evaluated. The surface oligomer concentration, fastness properties, and color of package dyed polyester yarns for the experimental alkaline conditions were compared to a control condition dyed in an acidic medium. The results of this investigation indicate that surface oligomer concentrations can be significantly reduced by dyeing in an alkaline medium. The fastness properties of the yarn dyed in the alkaline process without reduction clearing were equivalent to the fastness properties of the control dyed yarns with a reduction clearing procedure. The alkaline dye process did not reproduce the exact shade and hue of the control yarns.