Why does cotton dry so slowly?

Why does cotton dry so slowly?

I do not know if you have found such a phenomenon, chemical fiber materials are generally dry faster than cotton fabrics?

The question has been asked, does cotton not necessarily dry more slowly than synthetic fabrics?

Mention the cotton fabric in clothes will subconsciously feel easy to absorb water, and chemical fiber fabric always feel not absorb water. In fact, chemical fiber fabric can also absorb a lot of water, absorb more water, naturally need more time to vaporize, dry time to extend.

There are two main influencing factors, chemical adsorption and physical adsorption.

Chemical structure effects: Fabrics are composed of fibers, which are high molecular materials (such as cellulose in cotton fibers, silk fibroin in silk, and polyethylene terephthalate in polyester).

The main effect of water absorption is to see whether there are hydrophilic groups in the molecular structure, such as -OH hydroxyl group, -COOH carboxyl group, -SO3 sulfonic acid group and so on.

The existence of these groups can make water molecules adsorb on the fiber through the action of hydrogen bonds and ionic bonds, so as to improve the water absorption of the fiber.

Vinylon is a kind of fiber with good water absorption, the chemical name is polyvinyl alcohol acetal, which contains a large amount of water absorption group can absorb water, it has the reputation of artificial cotton.

As a chemical fiber, vinylon, some can even be dissolved in hot water. Its common fixed moisture return rate is about 5, far better than the common chemical fiber polyester 0.4.

Physical adsorption effect: Absorbent cotton fiber, not only because of chemical structure absorbent cotton fiber itself, in fact, the physical structure of cotton fiber also has great influence on water imbibition, cotton fiber inside waist round lumen, hollow structure of the cotton fiber is like a piece of very thin straw, water molecules can be inhaled through the capillary effect "cotton fiber inside, At the same time, the hollow structure also leaves sufficient storage space for water molecules and improves the water absorption performance.

They absorb a lot of moisture and take longer to evaporate, so cotton clothes tend to dry more slowly than synthetic clothes.

Presumably everyone has more or less used "dry hair towel", after washing hair with dry hair towel wipe can absorb most of the moisture, but we observe its fiber composition will find that most of it is polyester and nylon blend material. The two materials themselves do not absorb water very well, not nearly as well as natural fibers like cotton, but they do absorb water surprisingly well.

This "dry hair towel" is the full use of material physical properties of water absorption. Named "super fine denier fiber", is the way through the island spinning preparation, the filament with "sea" and "island" two components, the filament itself as thick as ordinary fiber, but dissolved by organic solvent to dissolve "sea" component, leaves especially fine "island" component, "superfine fiber" so was born.

Compared with the original coarse fiber, the superfine fiber has a larger specific surface area and is more attractive to water molecules. The dense interfiber also makes the water molecules adsorb to each other through the capillary effect. But water molecules themselves are hard to penetrate into fibers, so they evaporate easily into the air as free water.

This is why hair towels, although made of chemical fiber, absorb water better than cotton towels and dry faster than cotton fibers. If the "dry towel" and "cotton towel" are soaked thoroughly, the dry towel can absorb more water than the cotton towel and take longer to evaporate.

In short, cotton fiber molecules have a large number of polar groups, easy to absorb water. And cotton internal voids more capillary effect. Water can easily get inside the fiber. Polyester, on the other hand, has very few polar groups (only two segments of the macromolecular chain have them) and basically does not absorb water.

And the gap in the polyester fiber wechat structure is very small. Water molecules have a hard time getting in. In conclusion, the moisture content of cotton is much larger than that of polyester when cotton and polyester are soaked at the same time. And most of the water in the fiber, it is difficult to volatilize.