Effect of wetting pretreatment on structure and properties of plasma induced chitosan grafted wool fabric

Chitosan (CS) was grafted on the wool after being wetted at different relative humidity (5 %, 65 % and 95 % RH) and induced by O2 plasma to investigate the influence of wetting pretreatment on the structure and properties of plasma induced chitosan (PICS)-grafted wool fabric. The effects of the RH of wetting pretreatment, CS concentration and grafting time on weight gain ratio and PICS-grafted wool fabric properties including wettability, dyeability and shrink resistance were studied. Scanning electron microscopy (SEM) observation showed that the scales on the wool fiber wetted at 95 % RH and then treated by O2 plasma were more severely damaged. The surface roughness and polar group content of PICS-grafted wool fabrics increased with the RH of wetting pretreatment. The analysis results of surface morphology by SEM and chemical composition by X-ray photoelectron spectroscopy (XPS) revealed much more CS on the surface of PICS-grafted wool fabric wetted at 95 % RH. The analysis results of weight gain ratio, contact angle, K/S value and area felting shrinkage manifested the optimum parameters of PICS grafting on the wool fabric wetted at 95 % RH could be set as the chitosan concentration of 2 g/l and the grafting time of 2 h. The machine washable wool fabric with the area felting shrinkage of 4.5 % and the better wettability and dyeability could be obtained by a new ecologically acceptable process of PICS grafting on the wool wetted at 95 % RH.