Heat shrink tubing (also known as a heat shrink or) is a shrinkable plastic tube that is used for insulating wires, thereby providing environmental protection and abrasion resistance for stranded and solid wire conductors, terminals, connections and joints in electrical work.
The heat shrink kit, used around the world for multiple applications, was originally developed in the late 1950s by Paul Cook. It was manufactured using radiation chemistry. The heat shrink tube developed by Raychem is now used as the basic building block by different manufacturers worldwide.
Heat Shrink Technology – Compositional Analysis
Different prescribed ranges of thermoplastics can be used for manufacturing a heat shrink tube. These include polyvinyl chloride, polyolefin, Neoprene, Kynar, Viton (generally used for purposes involving high temperature in corrosive environments) and fluorinated ethylene propylene.
Other adhesive lining tubes used for making cables and connectors are used for creating powerful seals that are water resistant in nature. For providing a conducting connection between different objects without soldering them, a conductive polymer thick film is added to the heat shrink tube.
Science Behind Heat Shrink Tube
In general, the majority of plastics don’t shrink when introduced to heat; however, a heat shrink tube does. The nature of a heat shrink tube can be attributed to its cross-linking process; then polymer, when subjected to a radiation, generates covalent bonds to facilitate the process.
It has been used heavily ever since the World War II and different analyses carried out in this regard have revealed that a plastic memory is induced to the covalent bond by the cross-linking of the polymer, thereby making sure that it can be stretched to the required shape. However, please note that the tube will restore its original shape on the application of the desired heat.
The extent of which a tube can shrink
Different heat shrink tubes have different shrink ratio – the shrink ratio is measured as the shrunken size of a tube to its original size. For example, a tube having 2:1 shrink ratio can have an expanded diameter that is twice the size of the tube in its shrunken state.
Applications of Heat Shrink Tube
Heat shrink tubing is used in numerous activities for both protection purposes as well as aesthetic enhancements.
Various other uses include:
Identification – Color coding is used for easy identification
To harness multiple wires
Longevity – For manufacturing long-lasting, durable labels which are used in networking patch cords
Sealing – For stopping water and dust from entering splices
Insulation – Against excessive heat in military vehicles, boats, and aircraft
Barrier – It serves as a barrier between cables and various corrosive materials