Why does PVC heat shrinkable film shrink when exposed to heat?

Why does PVC heat shrinkable film shrink when exposed to heat? Hello everyone, do you know about shrinkable film? The author explains to everyone. The shrinkage of PVC heat shrinkable film after heating is a physical phenomenon, which needs to be explained by certain physical knowledge. Simply put, the thermal movement of molecules causes the shrinkage of PVC heat shrinkable film.　The macromolecules of ordinary plastic film are in a natural curl state, and generally do not shrink when heated. The situation of PVC heat shrinkable film is different. Its film formation has gone through two steps. After the raw material is melted, the film is stretched at a specified temperature and under the action of external force. The macromolecules cannot slip with each other, and the unnatural state is Froze.　At room temperature, plastic macromolecules have poor mobility, so molecular motion cannot be used to eliminate this unnatural state. This is the reason why PVC heat shrinkable film does not shrink at room temperature.　However, this is only a superficial phenomenon. There are unstable factors hidden in this seemingly stable PVC heat shrinkable film.　When the PVC heat shrinkable film is reheated to a certain temperature, the frozen macromolecules will start to move again and try to return to the natural state from the unnatural state, resulting in shrinkage. If you want to know more about the latest industry information about shrink film, please log in to our official website and we will bring you more practical tips.