Dyeing of raw ramie yarn with Reactive Orange 5 dye

The traditional grass cloth, which has a long history in China, is primarily constructed of raw ramie yarns. In this study, the dye adsorption of three reactive dyes (Reactive Red 2, Reactive Blue 194, and Reactive Orange 5) onto raw ramie yarns indicated that the high-temperature type of reactive dye was more suitable for dyeing raw ramie yarn. The adsorption kinetics for the sorption of Reactive Orange 5 onto raw and degummed ramie yarns was studied by applying pseudo-first-order and pseudo-second-order kinetics and the intraparticle diffusion model. The kinetics study revealed that adsorption primarily followed the pseudo-second-order model in the case of both yarns, and the adsorptions were spontaneous and exothermic. The adsorption isotherms were studied by applying Langmuir and Freundlich isotherm models and found that the Freundlich isotherm model was better fitted. The dyeing performance of Reactive Orange 5 on raw ramie fiber was investigated and compared with that of the degummed ramie yarn. The dyed fiber surface and cross-section were investigated using an optical microscope to understand the structural characteristics. The influences of different dyeing conditions and soap washing on gummy substance removal were also investigated. The tensile strength, stiffness, and colorfastness were also evaluated after raw ramie yarn washing. After the dyeing and soaping processes, gummy substances in the fiber were removed, and notably, they did not affect the water absorbency, tensile strength, and stiffness of ramie yarn.