Liquid ammonia dyeing of cationic ramie yarn with triazinyl reactive dyes

Cationic ramie yarn was prepared using a 2,3-epoxypropytrimethylammonium chloride agent. Subsequently, original and cationic ramie yarns were dyed in liquid ammonia with triazinyl reactive dyes (C.I. reactive orange 5, C.I. reactive red 2, and C.I. reactive green 19). The dyeing time was varied from 10 to 600 s with 10 % dye on mass of fabric (o.m.f) and dyeing concentration ranged from 1 to 100 % dye o.m.f for 600 s dyeing time at −35 °C at a liquor ratio of 35:1 were evaluated. After dyeing, the samples were baked at 100 °C for 10 min. The results indicated that the time taken to attain equilibrium for the original ramie yarn was 60 s and was 300 s for the cationic yarn. The cationic treatment increased the dye exhaustion and fixation and improved the wash fastness, but decreased the degree of rub staining. Pseudo first-order and second-order kinetic models were used to describe the kinetic data. The adsorption process of the liquid ammonia dyeing followed the second-order kinetics. The Langmuir and Freundlich adsorption models were applied to describe the experimental isotherms. The experimental data for dyeing untreated ramie yarn fitted the Freundlich model, but the kinetics of the cationic ramie yarn was found to fit the Langmuir isotherm.