DYEABILITY OF ARTIFICIALLY AGED COTTON FABRICS

A cotton fabric has been artificially aged by dry heat at 150 degrees C with or without initial exposure to ultraviolet light. The observed property changes in the aged cotton samples include a loss of breaking strength, a decrease in moisture regain, yellowing, and an increase i n carbonyl or carboxyl content. Dyeability is examined to characterize the physical and chemical changes in the aged samples. Dye uptake wit h direct dyes decreases as heating time increases, which can be attrib uted to increased crystallinity and the formation of carbonyl and carb oxyl groups. The decrease in dye uptake is more remarkable with the la rger molecular sized dye than with the smaller dye, indicating that so me changes have occurred in the size of the pores that accept dyes. Fr om the adsorption isotherms, we see that the dye adsorption mechanism is not similar for untreated and aged samples, due to chemical structu ral changes such as the formation of carbonyl and carboxyl groups. The slight increase in basic dye uptake is also attributable to carboxyl group formation.