Analysis on the characteristics of PVC heat shrinkable

Heat shrinkable film occupies a place in the field of packaging materials because of its 'heat shrinkage' characteristics of polymer materials. PVC heat shrinkable film has the characteristics of good shrinkage, moisture resistance, high toughness, good transparency, etc., and the packaging process is simple, beautiful in appearance, puncture resistance, and can also increase the added value of packaging products, cost-effective, and widely used in doors, windows, Aluminum, plaster wire, stainless steel, chemical products, electronic components and ceramics, metal accessories and other outer packaging.

It has been said before that PVC heat shrinkable film is made by rapid cooling after secondary inflation, so what principle is used?

The long linear polymer chains of PVC heat-shrinkable film are usually curled. When the polymer is heated and melted in a highly elastic state, the stretching orientation of the polymer chain is straightened under the action of external force, and the orientation state of the polymer chain is frozen after rapid cooling. When the temperature rises again, the polymer chain tends to be in a stable state, curls occur, and shrinks macroscopically. From the perspective of its shrinkage principle, there is no chemical change, so it is called 'physical reducibility'.