Is plastic wrap a polymer compound? Why are some plastic wraps sticky and some not?

Plastic wrap is made of polyvinyl chloride or low-density polyethylene, both of which are long-chain molecular polymers. The coiled long chains can be stretched so that the plastic wrap can be put on plates or bowls. If you want to know more about plastic wrap, for example: Is plastic wrap a polymer compound? Why are some plastic wraps sticky and some are not?

Contents of this article

1. Is plastic wrap a polymer compound?

2. Why are some plastic wraps sticky and some not?

3. What should I pay attention to when using plastic wrap?

Is plastic wrap a polymer compound?

Plastic wrap is a polymer compound, generally refers to a compound with a relative molecular mass of several thousand to several million. The vast majority of polymer compounds are mixtures of many homologues with different relative molecular masses. Therefore, the relative molecular mass of a polymer compound is the average relative molecular mass.

Polymer compounds are composed of thousands of atoms connected by covalent bonds. Although their relative molecular mass is large, they are connected in a simple structural unit and repeated manner. Although the relative molecular mass of polymer compounds is large, their composition is not complicated. Their molecules are often composed of specific structural units repeatedly connected by covalent bonds.

Why are some plastic wraps sticky and some not?

The stickiness of plastic wrap comes from two aspects: electrostatic force and molecular structure.

Plastic wrap is made of polyvinyl chloride or low-density polyethylene, both of which are long-chain molecular polymers. The coiled chains can be stretched to allow the plastic wrap to be wrapped around plates or bowls.

In addition, when the plastic wrap is unfolded, the electrons on its surface will separate between the two adjacent layers, making one side positively charged and the other negatively charged. Since the plastic wrap itself is a good insulator, static electricity will remain for a long time, and they will attach to objects with opposite charges, such as many plastic bowls, which have a slight negative charge on their surfaces.

When consumers buy cling film on a daily basis, they mainly distinguish between polyethylene and polyvinyl chloride products. Safe cling film is labeled PE cling film or polyethylene cling film; polyethylene cling film has poor stickiness and transparency and is easy to open after rubbing with hands, while polyvinyl chloride cling film has good transparency and stickiness and is difficult to unfold after rubbing with hands and easily sticks to hands.

What should I pay attention to when using plastic wrap?

1. It is necessary to poke holes when heating food. When using plastic wrap to cover food, you need to use a toothpick or other object to poke a few holes in the plastic wrap during the heating process to facilitate the evaporation of water vapor in the food. If you do not do this, it is very easy to cause gas expansion and cause the plastic wrap to burst, which will cause danger.

2. Do not wrap oily food. If the food is oily, such as fried food, do not use plastic wrap to wrap it. Especially during the heating process, the plastic wrap and oily food should be separated to prevent the high oil temperature of the food from melting the plastic wrap and sticking to the food.

3. Cooked food and meat are not allowed. It is best not to wrap hot dishes or cooked food, especially meat products, in plastic wrap for storage. This is mainly because if you use plastic wrap to wrap oily meat, the chemical components in the plastic wrap will evaporate and dissolve into the food, causing harm to the human body.