Modification of ramie fibre with a mixture of NaOH solution and iso-propanol solvent for enhancing its dyeing performance

Deep shade dyeing of ramie fibre is challenging due to its high degree of polymerisation, orientation, and crystallinity. The present work involved pre-treating ramie fibre with a solution containing a mixture of NaOH and alcohol in order to improve its dyeing ability. Based on the first screening results, it has been shown that iso-propanol is the optimal alcohol solvent for modifying ramie fibres with a mixture of NaOH solution, resulting in greater levels of dye exhaustion (E%), dye fixation rate (F%), total dye fixation efficiency (T%), and K/S values. Subsequently, the orthogonal array experimental technique (L16) was utilised to optimise the treatment conditions, and it was determined at a temperature of 25 °C, using a NaOH solution with a concentration of 140 g/L, a liquid ratio of 1:2 for the volume ratio of NaOH solution to iso-propanol solvent, and a treating period of 3 min. The treated samples were subjected to a range of analytical techniques, including XRD, FTIR, TGA, and SEM; these analyses conclusively verified that the samples' properties were altered due to the optimal combination treatment. The combination solution-treated samples had significantly higher barium values compared to the other samples, suggesting an ideal mercerisation treatment. The colourfastness to washing values exhibited satisfactory results for the treated samples. Besides, a handle assessment of raw ramie fabric and treated ramie fabric was conducted to enhance the practical application feasibility.