Why does a insulated bottle sometimes make a rustling sound when shaken up and down？

Insulated bottle is a daily item that we often use in our daily lives, which can effectively keep warm or cold, so that we can enjoy warm or cool drinks anytime and anywhere. The insulation effect of a insulated bottle is realized by its internal insulation layer, which is usually composed of a vacuum or an air layer filled with insulation material. However, when we pick up an empty bottle and shake it up and down, we will find that the inside of the bottle will make a rustling sound, why is this?

First of all, we need to understand the structure of the insulated bottle. Generally speaking, the internal structure of the insulated bottle consists of three layers: the inner layer, the middle layer and the outer layer. The inner layer is used to hold water, usually made of stainless steel or glass and other materials, the middle layer is the insulation layer, usually composed of a vacuum or an air layer filled with insulation materials, and the outer layer is the protective layer, usually made of plastic or other materials. The double-layer stainless steel structure and vacuum insulation design of a bottle can effectively reduce heat transfer and convection, and improve the insulation effect. Embedding copper or aluminum foil inside insulated bottles can further improve the thermal insulation effect and make them keep warm or cold for a longer period of time.

The presence of copper or aluminum foil creates a reflective layer that improves the insulation effect. The smooth surface of these foils reflects the radiation away, thus keeping the temperature warm or cold for a sustained period of time. When the bottle with copper or aluminum foil inside is shaken up and down, the foils will vibrate and produce a sound, which is the rustling sound that we hear.

Other sounds may also occur inside the bottle. For example, when there is water inside the insulated bottle, if the bottle is not sealed properly, it will produce air leakage sound or dripping sound. In addition, if the insulation layer inside the thermos is loose or broken, it will also make a rattling sound similar to rustling.

In the use of insulated bottles, when we hear the bottle inside the rustling sound, do not have to worry too much, because this is only copper or aluminum foil in the insulation layer inside the phenomenon produced by shaking up and down, will not affect the insulation effect. If there are other sounds inside the insulated bottle, we can check the sealing of the bottle and whether the insulation layer is broken, so as to find the cause of the problem and repair it.

In summary, the internal structure and materials of the insulated bottle have an important impact on its insulation effect and use experience. In daily use, we need to pay attention to the maintenance and care of the insulated bottle, to avoid loose or broken insulation layer, to ensure its long time insulation effect. At the same time, understanding the internal structure and materials of a insulated bottle can help us use it better and enjoy a better user experience.