Why do beverage bottles have five-petal flowers on the bottom?

Review expert: Meng Meng, associate researcher at the Institute of Physics, Chinese Academy of Sciences

During the Chinese New Year, soda can be said to be one of the must-haves for every household. Have you ever noticed that the bottom of all soda bottles are in the shape of a five-petal flower?

Source: Science Popularization China

Some people say that this is to hold less drinks or to make the shape look better, however, the truth is not that simple.

Source: Science Popularization Guangzhou

Looking back at the history of soda bottles, we found that early soda bottles were made of glass and had a flat bottom design . However, during use, it was found that flat-bottomed bottles were particularly prone to collapse. Not only were they unstable, but the oscillating bottle body when they collapsed also made it easy for carbonic acid bubbles to escape.

To address these issues, designers began experimenting with different bottom shapes.

Source: ifanr

In 1978, the world's first recyclable plastic bottle made of PET appeared, with a five-petal flower-shaped bottom . To this day, plastic bottles with five-petal flower-shaped bottoms for soda are still popular all over the country, and this design has also proven to be the most ideal choice.

Source: ifanr

1

Why is a five-petal flower-shaped bottle bottom better ?

From a chemical point of view, the carbon dioxide dissolved in carbonated beverages is extremely unstable. When subjected to external shaking or significant temperature changes, a large amount of carbon dioxide gas will escape, causing the volume of gas in the sealed beverage bottle to increase dramatically, exerting enormous pressure on the bottle.

Source: NetEase

In addition, if you observe carefully, you will find that the bottom of the plastic-packaged soda bottle is usually printed with the material label "PET". Compared with glass materials, PET materials have a very low hardness and are more likely to break or explode under strong pressure, which poses a great safety hazard. Therefore, the pressure inside the bottle must be dispersed and balanced at the bottom of the bottle through a concave design and a stretched rib structure.

According to the physical formula F=PS, the five raised structures can disperse the externally applied pressure (F) to a larger surface area (S) , thereby reducing the pressure per unit area (P) and alleviating the pressure load on the bottom of the bottle. This makes the soda bottle more stable when it is moved by external force or shaken manually, and less likely to burst or leak, thereby extending the shelf life of the soda.

Moreover, even if the plastic bottles are transported across the north and south in the cold winter, the huge temperature difference during transportation will not affect the sturdiness of the bottle.

Of course, the five-petal flower-shaped base can also be analyzed from a mechanical point of view to have a more stable placement effect . We must have learned in math class that "triangles have stability." The grooves at the bottom of the five-petal flower form a triangular structure that is concave inward, making the bottle more stable and reducing the possibility of accidental sliding or tipping.

During cargo transportation, this feature brings great convenience to the transportation workers. A large amount of cargo can remain stable and not collapse during transportation, thus ensuring safety.

Source: https://imagepphcloud.thepaper.cn/pph/image/254/741/216.png

Of course, aesthetics plays a small role, but it is nonsense to fill less beverages. Because each beverage has a specific capacity, merchants must strictly control the standard error range stipulated by the state when filling, and will never cut corners just because of the depression at the bottom of the bottle. Moreover, the five-petal flower-shaped bottom of the bottle also increases the surface area of ​​the bottle, which should have a higher production cost than a bottle with a flat bottom design, rather than reducing production costs.

2

Different packaging tastes different

In addition to soda in plastic bottles, we often see canned soda in our daily lives. Loyal fans of carbonated drinks should have discovered this problem: canned soda tastes more carbonated than plastic bottled soda. Why do different packaging produce different tastes?

Source: Sohu

To answer this question, we can explain it from a closed perspective.

Glass (mainly silicon dioxide) has the most stable molecular structure and a very tight texture. Even though carbon dioxide molecules are tiny, it is difficult for them to escape through many obstacles, so the "gas" you drink is the most abundant.

The basic material of the can is aluminum, which has good sealing properties and can maintain the gas content of carbonated beverages over a long storage period, maintaining the stimulating feeling of bubbles bursting on the tongue when drinking.

The PET material of plastic bottles is actually polyethylene terephthalate, which is a polymer material whose molecules are a huge and complex network structure, so its air tightness is worse than the previous two.

Of course, there is not much difference in taste between the two packages when they are just out of the factory, but the longer they are stored, the greater the difference in gas content among the three will become, and naturally they will taste different when drunk.

In short, the five-petal flower shape at the bottom of the soda bottle not only meets the functional needs, but also takes into account multiple aspects such as aesthetics, safety and convenience . Next time when you buy Coke, you might as well try different packaging methods and experience the differences, which may bring you unexpected surprises.