Application of D‐optimal design in the analysis and modelling of dyeing of plasma‐treated wool with three natural dyes

Abstract

AbstractBoth the dyeing and finishing of textiles with natural compounds are gaining increasing attention because of various environmental and health problems associated with the use of synthetic reagents. In this study, wool fibres were dyed with three natural dyes, namely, Arnebia euchroma, cotton pods and harmal seeds. Alum was used as the mordant, and samples were mordanted by the premordanting method. Oxygen plasma was employed for the surface modification of wool. Plasma treatment time, alum concentration, dyebath temperature and pH were selected as the process variables, and their effects on the K/S of the dyed samples were analysed using D‐optimal design. The surface topography, morphology and chemistry of the wool fibres after plasma treatment were studied by atomic force microscopy (AFM), scanning electron microscopy (SEM) and Fourier Transform–infrared spectroscopy (FTIR), respectively. FTIR confirmed the creation of new oxygen‐containing groups on the surface of wool fibres after plasma treatment. SEM and AFM images confirmed the surface etching and increase in the roughness of plasma‐treated fibres. Increasing the dyebath pH and temperature increased the K/S of the dyed samples. Increasing the amount of alum mordant increased the K/S of samples dyed with cotton pods but decreased the K/S of samples dyed with A. euchroma and harmal seeds. Increasing the plasma treatment time improved the K/S of samples dyed with A. euchroma and cotton pods but had no significant effect on the K/S of samples dyed with harmal seeds.