Application characteristics of the hottest nano ma

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Application characteristics of nano materials in military food packaging

military food has high requirements for packaging materials because of its special storage conditions and eating environment. The emergence of nano materials, with its special properties such as light weight, high strength, high barrier and versatility, can well meet the requirements of military food packaging materials, and has a broad application prospect in military food packaging. Nano materials 5) variable measurement of metal material outer diameter, variable pitch and variable steel wire diameter (3 changes) suspension measurement of metal materials to achieve Moldless processing refers to the material that controls the length and size of the constituent phase or grain structure below 100 nm, that is, the average particle size or size of nano materials is below 100 nm, mostly in the range of 1-100 nm. Nano material is a new member of the material family. It is a new type of material with excellent performance. It has excellent properties that ordinary crystalline materials and amorphous materials do not have. It has high strength and high barrier, high specific heat and high thermal expansion, high conductivity, magnetic susceptibility and diffusivity, strong absorption of electromagnetic waves, sterilization and disinfection and other functional characteristics. The application of nano materials in military food packaging can well meet the performance requirements of military food packaging in storage and eating, and improve the quality of military food

1. Nano materials have the characteristics of light texture and high strength

can reduce the weight of military food packaging. Thus reducing the load of individual soldiers. Because military food is mostly used in military marching, exercises, operations and other situations where it is inconvenient to carry out hot food support, its weight has an important impact on individual carrying and physical consumption. The current military food packaging materials mainly include tinplate, composite flexible packaging materials, plastics and so on. Among them, tinplate has the disadvantages of heavy packaging and inconvenient opening. Plastic packaging materials have poor stability and weak ability to resist adverse external environment, and generally cannot be used as packaging materials alone; Composite flexible packaging material is a new packaging material developed in recent years, which is composed of aluminum foil, plastic film, paper and cellophane, but it still has shortcomings in weight and strength, and needs further improvement

nanocomposite packaging materials are inorganic nanoparticles (silicate, carbonate, mica, quartz powder, etc.) uniformly dispersed in polymers with nanometer size. Due to their small size and close distance, nanoparticles have unique physical and mechanical properties such as quantum size effect, small size effect and superplasticity. Using the dislocation free or low dislocation density region caused by the small size effect of nanoparticles, it can achieve high hardness and high strength. For example, nano plastics containing a small amount (usually about 5%) of montmorillonite have the same rigidity, strength and heat resistance as conventional glass fiber or mineral reinforced composites, but they are light in weight, have high specific strength and specific modulus without losing their impact strength. When they are used in military food packaging, they can effectively reduce the weight of products, have high strength, and are convenient to carry and transport

2. Nano materials have high barrier, high flame retardancy and thermal stability, which can improve the protective performance of military food

military food is generally not eaten at ordinary times, but only in military exercises, operations and other situations, so the requirements for storage period and protective performance are high. For example, the storage period of military food of the U.S. military, whether canned or soft packaged, under the temperature of 21 ℃ is more than 2 years; The storage period of the combined rations of the British army is 3 years in the warm zone. Under the cooler conditions of 2 ℃ and 60% relative humidity, the storage period can be extended to 6 years: China's packaging technology can also store military food for more than 2 years under normal circumstances. In addition, under field conditions, military food is mostly stored in simple protective fortifications or stacked in the open air, which is easy to be polluted by enemy nuclear, chemical and biological weapons. Therefore, some military food packaging needs to have the "Three Prevention" function, that is, it can prevent the invasion of poison droplets and steam, it is easy to wash away, and it does not affect eating. The good combination of the polymer matrix and the clay layer in the nanocomposite packaging materials and the plane orientation of the clay layer make the nano materials show good dimensional stability and good gas barrier. Because the molecules of the nano filling materials can disturb the permeation routes of oxygen molecules and moisture molecules, the stronger the disturbance ability, the better the protective effect of the nano packaging materials

some nano materials are ideal flame retardant materials with high self extinguishing property, low heat release rate and high smoke suppression. For example, put polycaprolactone silicate nano plastic in the fire for 3O seconds, and after taking it out, the nano material will immediately stop burning. Applying the high temperature property of silicate to nano plastics can significantly improve its heat resistance and thermal stability. In addition, the nano powder with anti radiation function can be added to the polymer to make anti radiation nano materials. These properties of nano materials, used in the packaging of military food, can greatly extend the storage life of food and enhance the ability of military food to resist the adverse external environment

3. The recyclability and biodegradability of nano materials can improve the reusability of military food packaging and reduce environmental pollution

the environmental pollution of waste packaging of military food after eating has gradually attracted people's attention. For example, the United States has established a research project team on packaging waste of fast food rations (MRE) to improve the packaging of fast food rations by using nanotechnology. The current MRE outer packaging material is made of polyolefin thermoplastic, which is very thick; The main dish package consists of four layers of foldable bags, using aluminum foil, polyethylene, nylon and polyester as the packaging materials. According to the report of the dietary support Committee of the Department of defense of the U.S. Natick soldier center, the U.S. military will consume 47million field rations every year, which will produce more than 1400 tons of garbage. Because the packaging system uses a lot of aluminum foil materials, the packaging waste after eating is buried, causing environmental pollution. Similarly, aluminum foil and polyethylene are mostly used as packaging materials for military food in our army, and there are also environmental pollution problems of waste bags. 3. Reuse of pre packaging materials

the disposal of military food waste packaging can be solved by using nano packaging materials. The US military has developed a new MRE packaging material using nanotechnology, which is mainly composed of nano polymer film packaging bags. This nano material is filled with 1% - 5% montmorillonite and processed by indoor double helix equipment and film blow molding and extrusion equipment. The biodegradable nano composite composed of polyhydroxy acid in the preliminary test not only makes the transmission rate of water vapor exceed 200%, but also significantly enhances the physical properties such as hardness and elasticity. This kind of material is used in the outer packaging of military food and can replace the existing packaging materials such as aluminum foil, which greatly improves the reuse rate of materials and facilitates the treatment of packaging waste

4. The versatility of nano materials can improve the quality of military food and storage performance before stress is applied

in recent years, the emergence of functional nano coating materials, such as nano sterilization and disinfection coating, infrared absorption coating, infrared microwave stealth coating, insulation coating, electrostatic shielding coating, has brought the development of food packaging materials to a new stage. In terms of the preservation and sterilization of military food, nanotechnology is used to add filling materials with special properties to the packaging materials or apply a special nano coating on the surface of the materials. The nano functional materials produced have the effects of deodorization, sterilization and automatic disinfection, so as to prolong the storage period of military food and improve the edible quality of military food. For example, nano materials made of nano Ti02 and nano ZnO as photocatalytic bactericides have strong bactericidal ability, which can not only kill and remove bacteria and debris together, but also decompose Toxins Secreted by bacteria

in addition, nano technology can also be used to make sensors to indicate the quality of food, so as to prevent the harm of spoiled food to human body. Using nanotechnology, the University of Wisconsin has developed a sensor that can quickly detect harmful chemicals. Compared with traditional chemical detection devices, this sensor has not only high sensitivity and can detect 100ppb of chemicals, but also a large detection range. By changing the liquid to liquid ratio, it has decreased by 12.3% On the whole, this year, crystalline materials can detect different harmful gases. This sensor can detect the chemical substances released by rotten food and can be used to check whether the food is spoiled. Some coating materials, such as nano ultra-thin coatings (such as nano phase Ti02, ZnO, etc.) also have the function of chemical induction, which can be used for gas, light and humidity sensitive materials in military food, and for military food packaging. It can indicate the edible performance and various pollution levels of military food in the battlefield, realize the self diagnosis of military food, and thus enhance the edible safety. In short, nano materials have formed a certain scale after the development of recent years. It is predicted that nano industry will be the emerging mainstream industry in the 21st century. Therefore, we must increase the application research of nano materials in military food packaging, improve the scientific and technological content of military food packaging, so that it can better serve the army and improve the combat effectiveness of the army

reprinted from: China radiation protection

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