Why does stretch film stick to dishes?

The stretchable cling film is particularly practical for storing opened food or fruit. Where does its ability to stick to its surroundings come from, and why do some surfaces stick better than others?

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By packaging the food hermetically, the cling film helps to protect and protect it store the dishes started. One of the phenomena associated with its adhesive power is related to it static electricityof the same kind as the brush that “attracts” the hair, or the discharge that we sometimes feel when we take off a sweater.

When unrolling the hose electrons are torn from the surface of the plastic which is therefore positively charged, atoms lost negative charges. Stretch film is relatively good insulating, it holds the charge for some time. Some materials such as glass pottery are negatively charged, the two opposite charges attract each other, causing the film to stick.

Cling film doesn’t really stick… but it stretches

However, static electricity is not enough to explain adhesion, especially since the stretch film Also “sticks” to conductive materials such as metal or wet surfaces that are designed to distribute electrical charges and thus eliminate the charge difference. This adhesive force results in particular from the molecular structure of the plastic.

that cling film is made of polychloride vinyl (PVC), polyvinylidene chloride (PVDC) or polyethylene low density (PEDB) that have long chains polymers tightly tied and rolled up. This configuration gives it its highly extensible character (up to 200%) and allows it to be wrapped around containers.

To make their film even more “sticky”, manufacturers often add an additive (glycerin monooleate or polyisobutylene) at 0.5 or 2.5%. However, the stretch film tends to shrink after a few days, leading to loss of adhesion. Ironically, Cellofrais adheres much better to its own roller tube than to other surfaces!

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