Värmekrympande

Värmekrympande, also known as heat shrink, refers to a phenomenon where a material shrinks in size when exposed to heat. This property is utilized in various applications, particularly with certain types of plastics. When heat is applied to a specially manufactured heat-shrinkable plastic, its molecular structure changes, causing it to contract. Upon cooling, the material retains its new, smaller size.

The process typically involves manufacturing a plastic tube or film and then heating it to a temperature above its crystalline melting point. While in this heated state, it is expanded to a larger diameter or width. Once expanded, it is rapidly cooled to lock its molecular structure in the expanded state. When this material is later heated again, it "remembers" its original, smaller size and shrinks back to it.

Heat-shrink tubing is a common example. It is slipped over an object, such as electrical wires, and then heated with a heat gun or other heat source. The tubing shrinks tightly around the object, providing insulation, protection, and a neat finish. This is widely used in electronics, automotive repair, and electrical work. Other applications include heat-shrinkable film for packaging, which can be used to create tamper-evident seals or to secure products. The degree of shrinkage is predetermined during the manufacturing process, allowing for specific applications.