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In the textile industry, fiber structure is one of the important determinants of fabric dyeing performance. Taking cotton spandex collar rib as an example, the dyeing performance of this blended fabric is not only affected by the dye selection and dyeing process, but also deeply restricted by its fiber structure characteristics.
Chemical composition and dyeing performance of fibers
Cotton spandex collar rib is a blend of cotton fiber and spandex fiber. There are significant differences in the chemical composition of these two fibers, which directly affect the effect of the dyeing process. Cotton fiber is mainly composed of cellulose, and the molecular chain contains abundant hydroxyl groups (-OH), which can form hydrogen bonds with dye molecules, thereby enhancing the adhesion of dyes on fibers. Therefore, cotton fibers usually show excellent dyeing performance, especially strong adsorption capacity for reactive dyes and direct dyes.
In contrast, as a synthetic fiber, spandex fiber mainly contains functional groups such as ester groups and amino groups in its molecular chain. These functional groups have relatively weak affinity for dyes, resulting in poor performance of spandex fiber in the dyeing process. However, chemical modification methods, such as introducing more polar groups or adjusting the roughness of the fiber surface, can significantly improve the adsorption capacity of spandex fiber to dyes, thereby improving its dyeing performance.
Fiber supramolecular structure and dyeing performance
The supramolecular structure of the fiber, including crystallinity, orientation, size of amorphous region and pore distribution, all have an important influence on the dyeing performance.
Crystallinity: For fibers with high crystallinity, it is difficult for dye molecules to penetrate into the fiber, which leads to dyeing difficulties. Cotton fiber has a relatively low crystallinity, which allows dye molecules to penetrate more smoothly and achieve uniform dyeing. On the contrary, spandex fiber has a high crystallinity and limited penetration of dye molecules. Therefore, special processes or additives are required to improve its dyeing performance during dyeing.
Orientation: The higher the orientation of the fiber, the more complex the diffusion path of the dye molecules in the fiber, and the difficulty of dyeing increases accordingly. Cotton fiber has a low orientation, and the dye molecules can effectively diffuse along the fiber axis to achieve uniform dyeing. However, the high orientation of spandex fiber hinders the diffusion of dye molecules, and appropriate measures need to be taken to accelerate the diffusion process of the dye.
Amorphous region size and pore distribution: The amorphous region is the area where dye molecules can easily penetrate and diffuse. The larger the amorphous region and the more uniform the pore distribution, the easier it is for dye molecules to penetrate into the fiber and achieve uniform dyeing. The amorphous region of cotton fiber is relatively large and the pore distribution is uniform, so it exhibits good dyeing performance. Relatively speaking, the amorphous region of spandex fiber is small and the pore distribution is uneven, which makes it difficult for dye molecules to penetrate, thus affecting its dyeing effect.
Fiber morphology and dyeing performance
The morphological characteristics of the fiber, including cross-sectional shape, longitudinal morphology and surface roughness, also affect the dyeing performance.
Cross-sectional shape: The cross-sectional shape of the fiber directly determines the diffusion path of the dye molecules in the fiber. The cross-section of cotton fiber usually presents a more regular shape, which can effectively promote the penetration and diffusion of the dye. The cross-sectional shape of spandex fiber is more complex, which may cause certain obstacles to the diffusion of the dye.
Longitudinal morphology and surface roughness: The longitudinal morphology and surface roughness of the fiber also affect the dyeing performance. The surface of cotton fiber is relatively rough, which helps to enhance the adhesion of dye, while the surface of spandex fiber is relatively smooth, which may cause the dye to adhere poorly.
