In daily life, we pour boiling water into a plastic bottle and find that the bottle has shrunk! Some people say that this is the cause of thermal expansion and contraction, do you think this explanation is reasonable? We all know that boiling water is hot, according to the law of thermal expansion and cold contraction, the bottle should be swollen, why does shrinkage occur?
In fact, our common plastic bottles are made from a resin called polyethylene terephthalate (PET), which is thermoplastic and thermally stable. The process of manufacturing plastic bottles is made by injecting molten PET resin into a mold and then blowing it with compressed air. Because PET resin has a certain thermoplasticity, that is to say, after heating, the molecular structure inside the plastic can be deformed by flow, and can maintain a certain shape when cooling.
Then when we pour boiling water into a plastic bottle, due to the increase in temperature, the plastic inside the bottle will be affected by thermoplasticity, and then flow will occur. If we continue to heat continuously, the flow of the plastic will cause it to soften, which, combined with gravity, will eventually cause the plastic bottle to shrink and become smaller.
In addition, plastic bottles are made of PET resin, which is relatively safe under normal use conditions, and when subjected to high temperatures, a small part of harmful chemicals may be released, many research institutions have investigated the release of chemicals in plastic bottles, and according to a large number of experiments, high temperatures will cause some chemicals in plastic bottles to be released into hot water, among which dibenzoic acid (BPA) is a chemical widely used in the production of plastic products, which has the effect of interfering with endocrine.
In summary, due to the thermoplasticity of the plastic material, the plastic bottle will shrink when exposed to hot water, so that the material inside the plastic bottle will flow and deform after being heated, and eventually the bottle shrinkage will become smaller. In addition, when using plastic bottles, you need to be careful to avoid placing them in a high-temperature environment, because plastic bottles will release some harmful substances when exposed to high temperatures.
What do you think of the above, discuss it in the comment area.
Author: Hoard some knowledge.
The blogger who knows the most about life trivia.