A lot of "science"! PET bottle August 26, 15:15
On hot days, there are many people who can't let go of their plastic bottles because they take water. It's a familiar PET bottle, but in fact its shape is filled with the knowledge learned in "science" at school. This time it is a problem related to the shape of PET bottles!
Challenge the problem!
Problem
"Plastic bottle containers can be roughly divided into two groups. One is shaped like Figure 1 and the other is shaped like Figure 2. All carbonated drinks are shown in Figure 2. I found out that the carbonated drink is contained in a plastic bottle shaped like Figure 2 instead of the plastic bottle shaped like Figure 1. Why? Please choose the most appropriate reason from a to o below and answer with a symbol
. " Because it is easy to fill the beverage
. Because it is hard to break
c. Because it is easy to make
. It's easy to cool
. Easy to carry
(Azabu Junior High School 2013 retitled)
The big difference is that Figure 1 is square and Figure 2 is round.
I asked Mr. Kenichi Kaname, a general container manufacturer that also makes plastic bottles, about why containers are divided according to drinks.
Difference between carbonated drinks and other PET bottles
Before we get into the question, what's the difference between carbonated drinks and other containers? We tried to compared.
We prepared 8 plastic bottles, but Kaname says that you can tell at a glance what is for carbonated drinks. The point was not whether the material was hard or soft.
Kaname: The
point is that the body part is round. Another characteristic is the shape of the bottom. A carbonated bottle is a petal shape with five legs based on the round shape. As soon as you look at the bottom, you'll know if it's for carbonation."
Characteristics of plastic bottles for carbonated drinks
I had a special experiment show me what that shape means. Put carbonated drinks in plastic bottles for carbonated and tea.
Within minutes, the plastic bottles for tea changed.
Kaname
"The pressure of carbon dioxide pushes the inside of the container to the outside."
It seems that if the shape of the bottle changes, it may be damaged or burst when it is sold as a product. For carbonic acid, it is said that it has a shape suitable for the force that swells to the outside.
Mr. Kaname
"Originally, the torso part is rounded to suppress the bulge by applying uniform pressure to the whole body. The bottom is also stretched out so that it does not swell any more. The pressure is evenly distributed over 5 points. And the other thing is that it is self-reliant. Among the bottles that stand up, 5 legs is the most balanced."
So the answer is "a. It's hard to break."
In the experiment we conducted this time, we used a liquid that could not be used in the way PET bottles were originally used. Do not imitate, as it may result in unexpected injury.
If the characteristic of PET bottles that contain carbonated drinks is that the body is round and the bottom has five legs, that is not the only reason why the design of PET bottles for tea is important. It has functionality that carbonic acid does not have. I also experimented with it.
Functionality of plastic bottles for tea
This time, I put hot water in a plastic bottle for tea and carbonated drinks.
Then, the bottle for carbonic acid became distorted in shape. This is a phenomenon that occurs when the hot water inside cools.
Kaname:
"When it gets cold, the volume inside becomes smaller, so a phenomenon called "decompression" occurs. It is a force that is pulled inward."
Plastic bottles for tea have been designed so that they do not become distorted even if they are dented.
Kaname-san: A
square plastic bottle has a “panel” with unevenness between columns, and when the contents cool and shrink, the panel part dents to reduce the force of shrinking inwards. It has the exact opposite strength of carbonic acid."
It seems that this function will be needed in the beverage manufacturing process.
Mr. Kaname:
When manufacturing at a beverage manufacturer, there is also a method of heating the contents and filling them into bottles for the purpose of sterilization. There are teas that can be chilled and some PET bottles are kept hot. "
Plastic bottles that continue to evolve
PET bottles packed with various ideas. What kind of evolution will you make in the future?
Kaname talked as follows.
Mr. Kaname:
Recently, global environmental issues have been taken up, so I think we will be able to reduce the amount of resin used in bottles and move toward the direction of using recycled resin.
“Weekly Marukai News” (Broadcast on Saturday at 9 am), “Migake, Curiosity!” delves into the news every week, focusing on current affairs issues that were presented in the entrance examination.
Let's think of "Why?"
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