Down jacket can also be used as a life jacket

Recently, a suspicious woman jumped into the river, but she was rescued because she was wearing a down buoyancy jacket and had not sank into the river for more than 20 minutes. How can there be such a big buoyancy down jacket? According to experts, down jacket fabrics have “drinking water” characteristics, unlike the cotton and linen fabrics, which have strong permeability and air expansion in the down layer, so they have played a “life jacket” effect in a short time.

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The suspicious woman was saved by a down jacket

According to media reports, at 9 pm on January 10th, Ms. Li, a member of the Yanshi citizen, sang with her friends at KTV. During this period, Ms. Li was overdone because of her bad mood. At 2 o'clock on the morning of the 11th, Ms. Lee left KTV to go home with her friends and was ready to go home. After passing through a bridge over the river, Ms. Li asked to get off her hair and jumped into the river from her bridge when friends didn’t pay attention.

Subsequently, the fire department personnel and the nearby police station arrived at the scene. After deliberation, it was decided to use the river management agency's on-site vessel for rescue. After more than 20 minutes, Ms. Li was successfully rescued from the shore. After inspection by medical staff at the scene, Ms. Li was not seriously affected. "Because she was wearing a down jacket and jumped into the river, the down jacket had a buoyancy that prevented her from sinking and prevented a tragedy from happening," the police said.

Interpretation

Where does the buoyancy of the down jacket come from?

1. Most down jacket fabrics have "drip" properties that are not easily wet

Many people have this experience, wearing down jackets in the snow, into the room beat beat, snow into water, clothes are just a little wet, not a large wet. Other fabrics may be very wet. Why is this? According to experts, the reason why down jackets are not afraid of water is because their fabrics have "drinking water" characteristics. "The so-called 'water' property is a term in materials science, in fact, it is a performance index of the material's resistance to water penetration," said Professor Yin Shumei of the School of Chemical Technology of Qingdao University of Science and Technology. Most of the down jacket fabrics are chemical fiber materials of drowning water. When placed in water, they are not as wet as cotton and linen materials.

Due to the waterproof properties of the down jacket fabric (some of which are coated), water does not easily soak the fabric into the inside of the down jacket in a short time, and the air is not easy to run out. The down jacket should also be able to bring some helpers to float. effect.

Yin Shumei introduced that natural cotton and linen materials generally have strong “hydrophilic” characteristics, and down jacket fabrics are mostly synthetic chemical fibers. It is difficult for water to enter these fabrics. “Waterproofing is commonly used in raincoats and umbrellas. Most of the utensils are also made from such hydrophobic materials." Clothes made of this material, when dirty, can wipe off the surface with water to achieve a certain degree of cleansing.

2. The down volume of the down water is reduced. The air expands to obtain the buoyancy.

Like down jackets and raincoats, they all have waterproof characteristics. However, if the down jackets that Ms. Lee saved this time are replaced with raincoats, can they achieve the same effect? That may not be.

Another more important factor in getting down jackets to obtain buoyancy is the contribution of down. When the feathers are dry, they are bulky. The volume of down feathers is slightly reduced when soaked in water, and the air in the down layer expands, the volume becomes larger, and the specific gravity is lighter than water, so it can have the effect of “life ring”.

We also see this phenomenon in our daily lives. When using a washing machine to wash down jackets, the down jackets usually float, and it feels like there is a lot of air inside and the down jackets are inflated. However, if the air is squeezed out or wait for a period of time, it will be the reason why the down jacket will sink after all the down.

Yin Shumei introduced that not only down jacket fabrics are hydrophobic, but down jackets like duck down also have hydrophobic properties. Therefore, after Ms. Lee fell into the water, the down jacket first produced buoyancy and she had a lifting effect.

In short, the down jacket and the person are together in the water and the duvet is soaked for a short time. The air in the down layer of the down jacket will gradually expand, resulting in an increase in the volume of the entire down jacket. In this case, the density of the down jacket is It is much less than the density of water, so the down jacket takes on the role of the lifebuoy.

And if the lady wears a coat instead of a down coat, the clothes can easily sink due to water soaking into the water, and people will easily sink into the water.

Related interpretation

Are all down jackets buoyant? Depends on what material to use

Most down apparel fabrics have waterproof properties. Dirty clothes are wiped with a damp cloth, but some down jackets are made of cotton fabric. This type of down jacket does not produce any buoyancy in the water.

Yin Shumei introduced that the brand of the down jacket is different. The sewing method is different, and the waterproof degree of the fabric is not the same, so the time when the water is fully wetted is also not the same. Many down jackets sold in the market are different in the waterproof effect: For example, some down jackets can be used after wiping after being lightly showered; some down jackets can allow water droplets to drip on them and the rainwater will naturally fall off.

However, if it is exposed to rain or immersed in water for a long time, it will eventually sink even if it has a waterproof effect, because the inside of the down will eventually fully wet, and the down jacket will absorb a lot of water and become heavier and eventually sink.

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