Thesis Details

Thesis Title: A study of the dyeing behavior of polylactic acid fabric
Thesis Author: Shah "Sam" Huda
Abstract: American consumers generate more than 30 billion pounds of plastic wastes each year. These plastics eventually break down into harmless products, but only after several hundred years. Polylactic acid (PLA) fibers are produced from renewable resources, such as corn. These biodegradable fibers can be used in applications such as apparel, industrial, and institutional fabrics. The fibers have the same strength and elongation as PET, but are lighter and softer than PET. The objectives of this research were to study the effect of disperse dye structure on dyeing behavior of PLA fabric, optimize dyeing conditions, evaluate colorfastness of dyed PLA fabric, study the adsorption isotherm behavior of disperse dyes, and evaluate the effect of fiber morphology on dye uptake and mechanical properties of PLA. Dyebath temperature was varied from 70 to 130°C at 10°C intervals, pH from 4 to 8, and at a holding time of 90 minutes. Although dye exhaustion was higher at 110°C compared to 100°C for most dyes, tensile strength and elongation losses were also significantly higher at 110°C. At 130 DC, PLA filament yarns lost 100% of their tensile strength and elongation. Mechanical property losses were the minimum at pH 5. Near maximum dye exhaustion was observed in 20 to 30 minutes. High-energy azo and nitro diphenylamine dyes exhibited high levels of exhaustion. Anthraquinone, methine, and quinoline dyes had poor exhaustion. Overall, PET had better colorfastness properties and significantly higher dye uptake compared to PLA fabric. The PLA fabric from a second source had exhaustion similar to that of PET; however, losses of tensile strength and elongation were significantly higher than for the previous PLA. Disperse dyes followed Langmuir and Freundlich isotherms. A Nernst isotherm had a poor fit for all disperse dyes studied.