Relationship between structure and dyeing properties of reactive dyes for cotton dyeing

Heterofunctional reactive dyes were studied for their dye fixation and colour strength for cotton fiber. Reactive dyes with different reactive groups (monochlorotriazine and sulphatoethylsulphone) were applied on to cotton fabric with pad thermofix method to explore the role of functional group on colour strength and fastness properties. Dye fixation and colour strength of cotton fabric revealed that dye with different functional groups have different reactivity and affinity for the cotton fiber. Reactive dyes exhibited high colour strength at optimum conditions of temperature, pH and reaction time. Among dyes under investigation, D-6 (ester vinylsulphone at Para position) showed the highest colour strength (82%) and D-2 (ester vinylsulphone at Meta position) furnished minimum colour strength of 67%. The dyes having linear and planar structure offer higher reactivity. The fastness properties of cotton fiber for all reactive dyes were good to excellent in comparison to commercial Reactive Red 195 dye. (C) 2017 Published by Elsevier B.V.