Rays are usually invisible light emitted when a substance undergoes microscopic changes. It has a wide range of applications in military, medical and health, science, industry and agriculture. Here, only the use of radiation to prepare a magical heat-shrinkable material is described.
Plastics are widely used in people’s daily lives. Among them, polyethylene materials are a collection of linear molecules polymerized by ethylene monomers. They are everywhere in the market, but they do not have heat shrinkability. They are either film or pipe in the store. It is what it is when it is applied.
The so-called heat shrinkable material means that the material shrinks and deforms after being heated. If it is a thick tube when it is cold, it can be shrunk into a thin tube when heated and cling to the surface of the object to which it is attached, so as to ensure the insulation of the object or the corrosion protection of the metal surface. If the material is a film, use this to package the food. Once heated, the film material shrinks to tightly wrap the food to isolate the food from air and play a role in keeping fresh.
Why does this material have such magical properties? It is necessary to discuss from the structure of the material.
Ordinary polyethylene pipe does not have heat shrinkability. Polyethylene is polymerized by ethylene monomer. The molecular formula of ethylene monomer is H2C=CH2. Under polymerization conditions, the double bond of each ethylene monomer molecule is opened, and several molecules are polymerized into high molecular polyethylene in a linear shape. The polyethylene plastics we usually see are made up of linear molecules polymerized by ethylene monomers.
But under the action of radiation, polyethylene plastic will produce chemical bonds between linear molecules, which is radiation crosslinking. The greater the radiation dose, the greater the degree of crosslinking. As a result of radiation crosslinking, the polyethylene plastic changes from a linear structure to a network structure, that is, a three-dimensional structure. The newly generated material has a wonderful "memory effect". For example, the pipe can be expanded and then cooled to form a thick pipe. This kind of pipe can be restored to the original diameter of the plastic pipe before the pipe expansion, so it is called a "memory effect" material.
The pipe made of heat-shrinkable polyethylene material can be conveniently used to protect the joints of cables and optical cables, and the protection of metal pipe rods. The heat-shrinkable material can not only be prepared into a heat-shrinkable tube that shrinks in the radial direction, but also can be made into a plastic film that shrinks in both directions of warp and weft, which can be used in packaging and protecting articles. The magical heat-shrinkable material will bring more extensive applications to people's lives and industrial and agricultural production in the future.
Irradiation equipment is also the core equipment of heat-shrinkable materials. At present, Dongguan Sanlian Heat-shrinkable Company has two high-power electron accelerators.