Why does cloth absorb water and why can cloth absorb water

There are many tiny pores in the object that act as capillaries.

Capillarity. Wetted and non-wetted Put a drop of mercury on a clean glass plate, which is able to roll around without attaching to the glass plate. A clean glass plate is soaked in mercury and then removed, and no mercury is attached to the glass.

This phenomenon in which the liquid does not adhere to a solid surface is called non-wetting. In the case of glass, mercury does not infiltrate the liquid.

Put a drop of water on the clean glass and it will adhere to the glass plate to form a thin layer. When a piece of clean glass is immersed in water and then removed, the surface of the glass will be stained with a layer of water. This phenomenon of liquid adhering to a solid surface is called infiltration.

In the case of glass, water is an infiltrating liquid.

The same liquid, which is wetting for one solid, may not be wetting for another. Water can soak the glass, but not paraffin. Mercury cannot soak glass, but it can soak zinc.

Fill a container with an impregnated liquid, e.g. water in a glass beaker and bend the liquid side near the vessel wall as the water infiltrates the glass (Fig. 1A), and pack the non-wetting liquid in a container, e.g. mercury in a glass tube, and bend the liquid side near the vessel wall downwards because the mercury does not infiltrate the glass (Fig. 1B).This phenomenon is more pronounced in vessels with smaller inner diameters, where the liquid surface forms a concave or convex meniscus.

Capillary phenomenonInsert several thin glass tubes with different inner diameters into the water, and you can see that the water surface in the tube is higher than the water surface in the container, and the smaller the inner diameter of the tube, the higher the water surface inside. When these thin glass tubes are inserted into the mercury, the opposite happens, the mercury level in the tube is lower than that in the container, and the smaller the inner diameter of the tube, the lower the mercury level inside.

The phenomenon of the infiltrated liquid rising in the thin tube and the phenomenon of the non-infiltrating liquid decreasing in the thin tube is called capillary phenomenon. The tube that produces a pronounced capillary phenomenon is called a capillary.

Why can liquids rise or fall in capillaries? We already know that the surface of the liquid resembles a tensile rubber film, and if the liquid surface is curved, it has a tendency to flatten. Therefore, the concave liquid exerts a tensile force on the liquid underneath, and the convex liquid exerts pressure on the liquid underneath.

The liquid surface of the infiltrated liquid in the capillary is concave, it exerts a pulling force on the liquid below, so that the liquid rises along the pipe wall, and when the upward pulling force is equal to the gravity of the liquid column in the tube, the liquid in the tube stops rising and reaches equilibrium. The same analysis can also explain the phenomenon of non-wetting liquid falling within the capillary.

The water absorption is very good, for example, there are a lot of hydroxide groups in the cotton, which can form hydrogen bonds with water, and it is easy to combine with water. And there are many gaps in the inside of the cloth, which can form a capillary phenomenon and hold a lot of water.

Because water has surface tension, it can enter the small holes of the cloth.

Because the cloth is made up of a lot of fine hairs, the cloth absorbs water

The cloth is made of cotton, etc., so it absorbs water.

Reasons why cloth can absorb water:

The cloth has countless small pores, and about the cloth, the water is infiltrated liquid, when the cloth meets water, because the water infiltrates the cloth, the liquid surface in the small hole is concave, the liquid surface is similar to the tensioned rubber film, if the liquid surface is tortuous, it has a tendency to flatten. Therefore, the concave liquid exerts tension on the liquid below, and the convex liquid exerts pressure on the liquid below. The liquid surface of the infiltrated liquid in the capillary is concave, it exerts a pulling force on the liquid below, so that the liquid rises along the pipe wall, and when the upward pulling force is equal to the gravity of the liquid column in the tube, the liquid in the tube stops rising, forming a capillary scene.

Then the water filled the void of the cloth. The cloth absorbs water.

Generally, cloth is divided into animal fibers, plant fibers and chemical fibers.

Animal fibers are protein fibers, such as silk, wool, and rabbit hair.

Plant fibers are cellulose fibers, such as cotton and wood pulp fibers.

Chemical fibers are synthetic fibers, such as polyester (polyester), nylon (polyamide), spandex (polyurethane) and so on.

Among them, animal fibers and plant fibers are natural fibers, both of which contain hydrophilic groups, such as -OH, -NH, -COOH, etc., which have an affinity for water molecules, so whether they are animal fibers or plant fibers, they are hydrophilic, that is, they can absorb water.

Chemical fibers are petrochemical products and do not contain the above-mentioned hydrophilic groups, so the hygroscopic performance is very poor.

The principle of paper water absorption.

That's capillary phenomenon.

The capillary phenomenon is the result of a combination of the force of attraction between the object and the liquid and the surface tension of the liquid.

For the principle of capillary phenomenon, please refer to the encyclopedia "Capillary phenomenon":

The principle of water flowing to a higher place.

The flow of water to a high place is the siphon principle (i.e., the principle of the communicator), and the pressure applied to the liquid in a closed container is equal everywhere. The siphon is filled with water, there is no gas, the water level at the incoming end is high, and the water outlet is closed with the palm of the hand or other objects. At this time, the pressure in the tube is equal everywhere.

After everything is settled, open the water outlet, although the atmospheric pressure on both sides of Gaishen Town is equal, but the water level at the water end is high and the pressure is strong, pushing the water to flow out of the water outlet continuously. The siphon phenomenon is caused by the gravitational force and potential energy difference between the coarse liquid molecules of the nucleus, that is, the pressure difference of the water column is used to make the water rise and then flow to a lower place. Since the water surface of the nozzle is subjected to different atmospheric pressures, the water will flow from the high-pressure side to the low-pressure side, until the atmospheric pressure on both sides is equal, and the water surface in the container becomes the same height, and the water will stop flowing.

The use of the siphon phenomenon will soon be possible.

The water inside the container is pumped out.

Hope, thank you.

Paper is composed of fine fibers, the fiber limbs are not tightly combined, and the water will move along the small gaps between the fibers due to the capillary phenomenon after contacting the paper, which is also the main manifestation of the molecular force between objects. This force is largely unaffected by gravity.

What is capillary? The phenomenon of a liquid rising along a capillary or slit is called capillary phenomenon. Studies have shown that:

Only the liquid that infiltrates the wall of the tube can beat the fluid liter on the capillary, and the liquid that does not infiltrate the wall of the tube is down in the capillary. So how exactly does capillary phenomenon occur? In containers with a small inner diameter, such as capillaries, the liquid level is always curved.

The formation of the curved liquid surface causes the resultant force of the surface tension acting in the direction of the liquid surface section to produce an additional pressure, which produces a lifting effect on the liquid in the capillary, which leads to the occurrence of capillary phenomenon.

If the texture of the paper is better, that is, the paper fibers are tightly combined, like coated paper or something, the capillary phenomenon is not so obvious.

This force is largely unaffected by gravity, and the liquid surface is always curved. Pin cracking.

If the texture of the paper is good, this is also the main manifestation of the molecular forces between objects, like coated paper or something? Because the infiltrated liquid is in a container with a small inner diameter, such as a capillary. Studies have shown that this leads to the occurrence of capillary phenomena.

What is the capillary phenomenon, after the water comes into contact with the paper, this additional pressure has a lifting effect on the liquid in the capillary: only the liquid that infiltrates the wall of the tube can rise in the capillary, and the fibers are not tightly bound together. So how does the capillary phenomenon occur, because the capillary phenomenon will move along the small gap between the fibers, so that the resultant force of the surface tension acting in the direction of the liquid surface section produces an additional pressure, the liquid that does not infiltrate the pipe wall is reduced in the capillary, and the paper fibers are tightly combined, and the capillary phenomenon is not so obvious Paper is composed of fine fibers.

The formation of a curved liquid surface? The phenomenon of a liquid rising along the capillary or slit base bucket is called capillary phenomenon, that is, the phenomenon of capillary phenomenon.