Have you noticed this phenomenon? Chemical fiber materials generally dry faster than cotton fabrics?
Someone once asked this question, is cotton material not necessarily better than chemical fiber? Is the fabric drying slowly?
When it comes to cotton fabrics in clothes, you will subconsciously think that they are easy to absorb water, while chemical fiber fabrics I always feel like I am not absorbing water. In fact, chemical fiber fabrics can also absorb a lot of water. If they absorb more water, they will naturally need more time to vaporize and the drying time will be extended.
There are two main factors that affect whether fabrics absorb water, chemical adsorption and physical adsorption.
Influence of chemical structure: Fabric is composed of fibers, and fiber is a polymer material (such as cotton fiber cellulose, silk fibroin in silk, polyethylene terephthalate in polyester).
The main factor that affects the water absorption effect is whether there are hydrophilic groups in the molecular structure. For example -OH hydroxyl group, -COOH carboxyl group, -SO3 sulfonic acid group, etc.
The existence of these groups can make water molecules bond through the interaction of hydrogen bonds and ionic bonds. Adsorbed on the fiber, thereby improving the water absorbency of the fiber.
Vilon is a very water-absorbent fiber. Its chemical name is polyvinyl acetal, which contains a large amount of The water-absorbent group can absorb moisture, and it has the reputation of artificial cotton.
As a chemical fiber, some vinylon can even be dissolved in hot water. Its official moisture regain is around 5, which is far better than the 0.4 of common chemical fiber polyester.
Influence of physical adsorption: Cotton fiber has good water absorption, not only because of the chemical properties of cotton fiber itself The structure absorbs water. In fact, the physical structure of cotton fiber also has a great influence on water absorption. There is a waist-round cavity inside the cotton fiber. The hollow structure makes the cotton fiber like a very thin straw, and water molecules can pass through. “Capillary effect” is sucked into the interior of the cotton fiber. At the same time, the hollow structure also leaves sufficient storage space for water molecules, improving the water absorption performance.
Absorbing a large amount of water will take longer to evaporate, so cotton clothes are generally dryer than chemical fiber clothes Slower.
I believe everyone has used a “drying towel” at one time or another after washing their hair. Wiping with a dry hair towel can absorb most of the moisture, but if we look at its fiber composition, we will find that most of it is a blend of polyester and nylon. The water absorption of these two materials is not very good, far less than natural fibers such as cotton fiber, but their water absorption is surprisingly good.
This “dry hair towel” makes full use of the physical properties of the material to absorb water. The scientific name is “superfine denier fiber” and it is prepared through island spinning. Sea-island silk has two components: “sea” and “island”. Sea-island silk itself is as thick as ordinary fiber, but it is dissolved by organic solvents. After dissolving the “sea” component, only the extremely fine “island” component remains, and thus “superfine denier fiber” was born.
Ultra-fine denier fiber has a larger specific surface area than the original thick fiber and is resistant to water The attraction of molecules is also stronger, and the dense spaces between fibers also cause water molecules to be adsorbed to each other through the capillary effect. However, it is difficult for water molecules themselves to penetrate into the fiber, so the water molecules will easily evaporate into the air in the form of free water.
This is why although dry hair towels are made of chemical fiber, they absorb water better than cotton towels , the drying speed is faster than cotton fiber. If the “dry hair towel” and “cotton towel” are fully soaked, the dry hair towel can absorb more water than the cotton towel and takes longer to evaporate.
In short, cotton fiber molecules have a large number of polar groups, which are easy to Adsorbs moisture. Moreover, there are many internal voids in cotton, which has a capillary effect. Water easily enters the fiber. Polyester, on the other hand, has very few polar groups in the molecule (only two segments of the macromolecular chain) and basically does not absorb water.
And the polyester fiber microstructure has very small gaps. It is difficult for water molecules to enter. In summary, after cotton and polyester are soaked at the same time, the moisture content of cotton is much higher than that of polyester. Moreover, most of the water is inside the fiber and is difficult to evaporate.
