Effect of Pretreatments on Wettability and Dyeing Property of Cotton Fibers in an Environmentally Friendly Dyeing System

To investigate the influence of cotton wettability on its dyeing properties in a silicone non-aqueous dyeing system, alkali pretreatment was performed before dyeing. The dyeing properties and dyeing kinetics of reactive dyes in the non-aqueous system and a conventional dyeing system were compared. Alkali pretreatment significantly improved the wettability of cotton fiber by removing wax and pectin. The adsorption rate of dye increased with increased cotton fiber wettability using the non-aqueous system, while it barely changed using the conventional system. Pseudo-second-order kinetics fit well with dye adsorption for both systems. Dye fixation improved by 30% at a concentration of 2% owf, along with better levelness and color depth of the dyed cotton fiber, using the silicone non-aqueous system without salts and dispersants.

Improved cationic dyeability of thermotropic liquid crystal polyarylate fabrics by ultraviolet irradiation-induced grafting of acrylic acid

As one of the most promising high-performance fibers, it is worthwhile to investigate the dyeing property of thermotropic liquid crystal polyarylate (TLCP) fibers. In this work, ultraviolet (UV) irradiation-induced grafting using the acrylic acid (AAc) method was employed to improve the cationic dyeability of the TLCP fabrics. The TLCP fabrics were firstly immersed in an AAc monomer solution for 24 h, followed with the UV radiation process for grafting polymerization. The results showed that the dyeing performance to C.I. Basic Red 46 of the modified TLCP fabrics was remarkably improved. Through several characterizations, it was found that the AAc-grafted TLCP fibers became more roughened with many pits on the fiber surface, while the crystalline structure of the TLCP fibers was hardly affected. More importantly, carboxyl groups have been successfully introduced onto the TLCP fiber surface, which is the main reason for the good dye uptake. Therefore, this paper provides a simple and efficient way for the improvement of the cationic dyeing property of TLCP fabrics.

Study on structure and properties of natural indigo spun-dyed viscose fiber

To improve the level dyeing property and colorfastness of natural pigment-dyed cellulose fiber, a study on the structure and properties of natural indigo spun-dyed viscose fiber was carried out systematically. Herein, the natural pigment-dyed cellulose fiber was prepared by wet-spinning technique, and the microstructure of the colored fiber was comprehensively studied. Fabrics with different color depths were obtained by adjusting the color value and the content of indigo pigment. The natural indigo was evenly embedded in the viscose fiber, and the results indicated the existence of a direct ratio relationship between the performance of natural indigo and the color depth of the fiber. The level dyeing property and colorfastness of the fabric were tested. The fabric exhibited excellent dyeing uniformity, as indicated by the relative standard deviation of the surface color depth value on the fabric, which was no more than 2.39%. The colorfastness of natural indigo spun-dyed fiber was outstanding even when mordant was not used in the production process. The colorfastness to artificial light could reach grade 5, the fastness to washing with detergent reached grade 3–4, the fastness to rubbing reached grade 4–5, and that to high temperature reached grade 4–5. These results can possibly promote the future use of natural dyes in the fiber produced by a spun-dyeing technique.

Adsorption and dyeing properties of acid dyes on fine denier silk fibers

In this work, the surface morphology and diameter distribution of fine denier silk fiber were observed and measured. The adsorption property of acid orange 7 on the fine denier silk fiber was studied. The pseudo-first-order model and pseudo-second-order model adsorption kinetic models were employed to evaluate the experimental data. The effects of pH values and reaction temperature on the dyeing property were investigated. The results indicated that the fine denier silk fiber exhibited a uniform fiber diameter (9 µm), which is smaller than that of conventional silk fiber (16 µm). The adsorption process of the dye could be described using pseudo-second-order kinetic equations. A higher the amount of dye adsorption at equilibrium and faster adsorption rate was obtained for the fine denier silk fiber. The color strength of fine denier silk fibers was improved for the decreased pH values and increased temperature, which exhibited an excellent dyeing property.

Study on enzyme washing process of hemp organic cotton blended fabric

Purpose At present, the enzyme washing process is widely used in hemp garment in the industry. However, it has many disadvantages. First, it is inefficient and labor-intensive, which can only be produced in small quantities and will take much time for workers to check. Second, its cost is high. The strength loss of the garment is up to 20 percent, with a bad damage. Presently, the enzyme washing process of the gray fabric is not industrialized. The purpose of this paper is to obtain a stable and efficient process for the enzyme washing of the gray fabric. Design/methodology/approach The whiteness, weight loss rate, strength, dyeing property and fabric style of enzyme washed gray fabrics were studied. Findings The results showed that the enzyme treated fabric has soft handle, smooth surface, good elasticity and high levelness, as well as low strength reduction rate under the optimized condition of bath ratio of 1:12, cellulase dosage of 0.3 percent, pectinase dosage of 1 g/L, treatment temperature of 55°C, treatment time of 80 min and pH of 6. Originality/value First, the process is environment friendly, green and sustainable and, second, it will make the industrialization of the enzyme washing process of gray fabrics, with a high commercial value.