COLOURABILITY AND FASTNESS OF COLOURED POLYESTER KNITTED FABRIC AFTER PRETREATMENT

Abstract

The effects of pretreatment on the dyeing efficiency of polyester knitted fabric using a yellow disperse dye were investigated in this study. The raw fabric was pretreated with an alkaline solution (calcium hydroxide) and pure higher alcohols (1-pentanol and 1-octanol), while dyeing was carried out in the presence of an environmentally friendly carrier (caffeine). The results showed that pretreatment improved dye uptake during the dyeing process. Significant weight loss was observed after treatment with 1-octanol (8.2%), resulting in the greatest fabric swelling (thickness increase). Shrinkage was uniform across all samples, averaging around 3%. The tensile strength of the pretreated fabric was slightly reduced, particularly in the sample treated with alkali. The CIELab colour system parameters showed more intense colouring in all samples; for example, the sample modified with 1-octanol exhibited the darkest shade. The sample pretreated with 1-octanol was the darkest, as confirmed by the highest difference in lightness (ΔL = −18.23). In addition, its high chroma (C = 32.47) and hue angle (H = 86.23) contribute to a pronounced yellow colouration with good brilliance. These CIELab parameters, along with the subjective evaluation of colour levelness, confirm the significant colouration and the effectiveness of this modification in achieving intense and uniform dyeing. Caffeine proved to be an effective, non-toxic carrier, enabling better dyeing results than procedures without a carrier or those using a conventional carrier. The colour fastness of the pretreated polyester knitted fabrics to light, washing, rubbing, seawater, and water drops was found to be satisfactory and acceptable.