Plastic bottles can shrink when exposed to hot water and pop open when kept in a freezer due to the properties of the plastic and the effects of temperature changes. The phenomenon is primarily attributed to the thermal expansion and contraction of the plastic material.
When hot water is poured into a plastic bottle, the heat causes the plastic to expand. However, when the hot water is removed or cools down, the plastic quickly contracts due to the decrease in temperature. The rapid contraction of the plastic can cause the bottle to shrink and deform.
The opposite effect occurs when a plastic bottle is placed in a freezer. The cold temperature in the freezer causes the plastic to contract. As the plastic contracts, it exerts pressure on the contents of the bottle, and if the pressure exceeds the strength of the bottle or its cap, it can lead to the bottle popping open or cracking.
The behavior of plastic in response to temperature changes is influenced by its thermal expansion coefficient, which is a measure of how much a material expands or contracts with temperature variations. Different types of plastics have different coefficients, and some plastics are more prone to shrinkage or expansion than others.
Additionally, the shape and design of the bottle can also affect its response to temperature changes. Bottles with thin walls or weak structures are more likely to deform or rupture under temperature extremes.
It's important to note that not all plastic bottles behave the same way, and the extent of shrinking or popping open can vary depending on factors such as the type of plastic, bottle design, thickness, and the magnitude of temperature change.
It's generally recommended to use bottles specifically designed for hot liquids when pouring hot water into them, and to use freezer-safe containers for storage in the freezer, to minimize the risk of deformation or damage.