Heat shrinkable film, let’s take a look

“Accelerators for America's Future” published by the Office of Science of the U.S. Department of Energy has such a description: Eat fresh and tender roast turkey for energy saving, don’t forget to be grateful for particle accelerators, because American food processors have been using particle accelerators for decades. Take the cross-linked plastic film-heat shrinkable film to pack the turkey. Heat shrinkable film? It sounds strange, but it has penetrated deeply into our lives. 'Accelerators for America's Future' (part of the chapter) (picture from the Internet) plastic film Let us first understand the more familiar plastic film. The main component of plastic is resin. Natural resin is a secretion of trees (that is, the layer of yellow colloid at the cut after the branches are sawed). Synthetic resin is a kind of synthetic high molecular weight polymer, which is made up of many identical and simple structural units repeatedly connected by covalent bonds (like a pearl necklace). Schematic diagram of polymer molecular structure (picture from the network) Synthetic resin has lower density, higher strength and better corrosion resistance than natural resin. Using synthetic resin as the main component, plus some auxiliary materials such as plasticizers, fillers, lubricants or coloring agents, you can produce plastic materials with certain characteristics-called 'plastics'. Looking back in history, it was the Belgian American and chemist Leo Baekeland who successfully developed plastic for the first time in the early 20th century. Baekeland registered related patents and opened a factory for mass production of plastics. Some sources call him the 'father of plastics.' Plastic films are widely used in the packaging of food, medical supplies and other items, bringing great convenience to people's lives. However, plastic products have many weaknesses, such as poor temperature resistance, easy cracking or tearing, etc. Scientists have been trying to improve the performance of plastics. With the development of science and technology, the British scientist Arthur Charlesby made a breakthrough in related research in the early 1950s. He found that polyethylene (a kind of plastic) can become a heat-shrinkable material with a special 'memory effect' after being treated by irradiation cross-linking technology. Charles Bay published a series of papers on the research of radiation cross-linking technology. His pioneering work has greatly promoted the research and development of cross-linking technology in the field of radiation polymers. Related papers published by Charles Bay (picture from the Internet) What is radiation crosslinking technology? That is to say, under certain irradiation conditions, the molecular structure of the plastic is transformed from the original linear chain structure to a three-dimensional network structure, which causes the physical and chemical properties of the plastic to change-this is the radiation crosslinking reaction. Schematic diagram of linear molecular cross-linking (left) and network structure (right) (picture from the network) This heat-shrinkable material expands and becomes very elastic when heated to a certain temperature, stretches it into a film, and then Lower the temperature to room temperature, but it can still maintain the state when it expanded. If you use it to wrap something, for example, wrap a plump turkey, and just heat the film again, a miracle will appear: the film shows a 'memory effect' and automatically shrinks to its unexpanded state. The plump turkey was tightly sealed by the film. This type of radiation crosslinked plastic film is called a heat shrinkable film. The crosslinking reaction of plastics can be achieved by chemical methods (such as adding a crosslinking agent) or physical methods (such as irradiation). The radiation cross-linking reaction by physical methods can be used to irradiate plastics with radiation (X-rays, γ-rays, neutron beams, particle beams, etc.) produced by a certain radioactive source, light source, electrostatic accelerator, or high-power electron linear accelerator. The highest is the high-power radiation device-particle accelerator. Schematic diagram of electron accelerator irradiation treatment of plastic film (picture from the Internet) After the plastic film is irradiated with the particle beam from the particle accelerator, it becomes super strong and has thermal shrinkage characteristics due to the cross-linking reaction. Food processors buy large quantities of this heat-shrinkable film from plastic manufacturers for packaging various types of food, making fresh food more attractive. Several electronic accelerators used in a US factory to produce cross-linked heat shrinkable film (picture from the Internet) Shrink film products (picture from the Internet) are widely used. Nowadays, heat shrinkable films are widely used in food, medicine, disinfection tableware, cosmetics, and sports Packaging of supplies, office supplies, craft gifts, printed matter, mechanical parts, electronic and electrical products, building materials, etc. For the combination packaging of irregularly shaped items and the packaging of super large items, the use of heat shrinkable film has greater advantages. It can not only meet the functions of moisture and dustproof, anti-touch, transparent display, etc., but also increase the appearance of the product. Appeal. Heat-shrinkable film combination packaging of commodities (picture from the Internet) High-speed heat-shrink film packaging machine (picture from the Internet) heat-shrinkable film packaging of printed matter (picture from the Internet) heat-shrinkable film packaging of artwork (picture from the Internet) Heat of large items Shrink film packaging (picture from the Internet) heat shrink film is only one of the many applications of radiation crosslinking technology. After the cross-linking reaction, all kinds of plastics have greatly improved their comprehensive properties such as environmental stress cracking resistance, heat resistance, oil resistance, flame resistance, chemical resistance, creep resistance and electrical properties, and significantly increased the heat-resistant temperature and broadened their applications. field. Radiation cross-linked wires, cables, various types of pipes and plates are widely used in automobiles, airplanes, electronics, construction, and large-scale projects. However, polyethylene foam plastics treated by irradiation and crosslinking have special advantages in insulation, construction, life-saving, and heat insulation. Heat shrinkable film, heat shrinkable bag manufacturers-comparison of characteristics of plastic bags, POF heat shrinkable film and PVC film