1. Moisture absorption and perspiration mechanism
Moisture wicking mechanism of fabrics: The transfer of sweat by fabrics can be roughly divided into four stages: contact, wetting and absorption of fabrics and sweat; transfer of sweat; storage or retention of sweat; evaporation of sweat from the surface of the fabric. Therefore, after the human body sweats, the sweat does not spread on the inner surface of the fabric, but is directly sucked to the outer layer of the fabric and evaporates on the outer layer of the fabric to keep the inner layer of the fabric relatively dry and reduce the adhesion between the human body and the fabric. Effect, improving human comfort and human movement function [2].
2. Main factors affecting the hydrophilicity of polyester fiber or fabric
(1) Surface and cross-sectional shape of single fiber
Fibers with microscopic unevenness on the fiber surface or irregular cross-sectional shapes have good water absorption. This is because the change in the smooth and complete surface structure of the fiber not only increases the specific surface area and affinity to water molecules, but also uses the principle of microporous capillary water absorption to increase the amount of water retained in the gaps between fibers.
(2) Type and quantity of hydrophilic groups
The type of hydrophilic group is important. Polar groups such as meridians, amino groups, phthalamine groups, carboxyl groups, etc. have strong affinity for water molecules. Therefore, the greater the number of such polar groups in the fiber molecular structure or on the fiber surface, the better the hygroscopicity.
(3) Supramolecular structure of fiber
The higher the crystallinity of the fiber, the worse the water absorption. This is because in the crystalline region of the fiber, the molecules are tightly arranged in a regular manner, and the polar groups are cross-linked between the molecules, making it difficult for water molecules to penetrate into the crystalline region.
3. Moisture-wicking finishing method
There are many methods to improve the hygroscopicity of polyester fabrics, such as blending, hydrophilization of macromolecular structures, graft copolymerization with hydrophilic substances, fiber surface treatment, etc. The method of using hydrophilic agents to evenly and firmly fix them on the fiber surface to form hydrophilicity is the development direction of moisture-wicking finishing of synthetic fiber fabrics in recent years. (1) Chemical modification: There are three main chemical methods to improve the hydrophilicity of polyester fabrics: hydrophilization of the macromolecular structure, graft modification with hydrophilic monomers, and hydrophilization treatment of the fiber surface. (2) Physical modification: There are three main ways to improve the hydrophilicity of polyester fabrics through physical methods: blending with hydrophilic substances or composite spinning, special-shaped treatment of fiber structure, and fiber surface roughening [2].
4. Hygroscopic finishing of polyester fabric
Since the physical modification method requires relatively high spinning equipment, the cost of moisture-wicking polyester fabrics increases. This article uses the new finishing agent A provided by the company (because it is a new product of the company, it is not convenient to provide the name and ingredients) and the traditional cationic moisture-absorbing and perspiration finishing agent B, so that they can be evenly and firmly fixed on the fiber surface to form hydrophilic groups. From the human body sweating to the fabric completely draining the sweat, there are three processes: first, the fabric absorbs sweat to distribute the sweat to a certain amount between the skin and the fabric, then the sweat diffuses in the fabric, and finally the sweat evaporates from the fabric. In these three steps Poor indicators at any step will affect wearing comfort. Therefore, at least three tests, each representing a step in the perspiration process, should be used to comprehensively evaluate the moisture wicking performance of the fabric. Therefore, this article chooses to comprehensively evaluate the finishing effect of the chemical finishing methods of finishing agent A and finishing agent B by testing the comprehensive value of capillary effect, drying rate, durability, comprehensive moisture conductivity value and air permeability.
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