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Introduction to the principle of mercerizing process 4

4, the change of fiber after mercerizing:


1. Morphological structure

The fiber diameter increases and becomes round, the longitudinal natural distortion rate changes (80%→14.5%), the cross section changes from waist shape to ellipse shape, even round shape, and the cell cavity shrinks to a point. If appropriate tension is applied, the roundness of the fiber increases. The original wrinkles on the surface disappear, the surface smoothness, the optical properties are improved (the reflection of light is converted from diffuse reflection to more directional reflection), the intensity of the reflected light is increased, and the fabric exhibits a general luster.

The change in fiber morphology within the fabric is the main cause of gloss, and tension is a major factor in enhancing gloss.


2, microstructure

The crystallinity ↓(70%→50%), the amorphous region ↑, makes the hydroxyl group which is inaccessible in water become accessible, so the adsorption performance and chemical reaction performance of the dye on the dye are improved, and The fiber morphology changes, and the light scattering on the surface and inside is reduced, so the dyeing depth is also increased when the dye of the same concentration is dyed.

After the fiber swells, the hydrogen bonds between the macromolecules are disassembled. Under the action of tension, the arrangement of the macromolecules tends to be neat, and the degree of orientation is improved. At the same time, the uneven deformation of the fiber surface is eliminated, and the weak link is reduced. The fiber can evenly share the external force, thereby reducing the fracture caused by stress concentration. In addition, the fibers after the expansion and rearrangement are close to each other, and the cohesive force also reduces the factor of fracture caused by the slippage of the macromolecule.


3. Changes in molecular structure

After the cotton fiber swells in the concentrated alkali solution, the hydrogen bonds between the macromolecular chains are disassembled, and the internal stress stored in the fabric is relieved. By stretching, the macromolecules are aligned, and a new position is established in the new position. Molecular bonds, and the intermolecular force is greater than before swelling. Finally, under the tension, the hydrogen bonds between the aligned fibers are fixed (which are fixed in a more natural and stable state), and the fibers are in a lower energy state, so the size is stable.



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