Radiation commercial applications

Ozone in the lower atmosphere is also produced as a result of modem technology. Equipment that produce sparks, arcs, or static discharge ultraviolet and other ionizing radiation commercial applications such as air purifiers and deodorizers in homes, hospitals, and offices and closed environmental systems such as aerospace cabins and submarine chambers due to electric discharge from equipment or ionizing radiation, are some examples. 

Radioisotopes have important commercial applications. For example, americium-241 is used in smoke detectors. Its role is to ionize any smoke particles, which then allow a current to flow and set off the alarm. Exposure to radiation is also used to sterilize food and inhibit the sprouting of potatoes. Radioisotopes that give off a lot of energy as heat are also used to provide power in remote locations, where refueling of generators is not possible. Unmanned spacecraft, such as Voyager 2, are powered by radiation from plutonium. 

The role of CFCs in the destruction of ozone in the stratosphere was something of a surprise to some researchers because those compounds are normally quite stable. In fact, their stability is one of their most desirable properties for many industrial and commercial applications. But, when CFCs escape into the atmosphere and drift upward, they are exposed to ultraviolet radiation in sunlight and, as is oxygen itself, are dissociated by that radiation. In the case of Freon-12 (CCI2F2), photodissociation results in the formation of free chlorine atoms ... 

The main potential for expansion of UV/EB into aerospace and certain commercial applications is by developing radiation curing of polymeric fiber-reinforced composites. The initial work on composite skin repairs involve applying the UV curing technology with bisacryl phosphine oxide to ensure the cure of relatively thick layers. A total of ten layers were used at a time. The UV cured composites closely matched those produced by heating. ... 

A Very practical application of infrared radiation is found in radiant heating. Solid radiators, such as hot tungsten filaments, alloy wires, and silicon carbide rods arc used widely as sources of infrared to provide surface healing by radiation. Commercially available infrared lamps are extensively used in specially designed ovens for drying painted and enameled surfaces. 

Variables affecting the homopolymer yields in acid have been examined and include radiation dose, dose-rate and concentration of monomer in solvent. Water is shown to have a different effect to acid. M values on all homopolymers from the above runs are lower in acid than in neutral solution. The significance of the molecular weight data in grafting and homopolymerisation is discussed especially with respect to possible commercial applications of the graft copolymers of cellulose. 

In the present work, further mechanistic data for the acid effect in both UV and gamma radiation systems are reported, particularly molecular weight studies on the species present in the grafting solutions. The significance of these acid effects in possible commercial applications of the resulting copolymers of cellulose is also briefly mentioned. 

Next to the generation of electric power, radiation processing is potentially the most important commercial application of nuclear energy. Radiation processes have been developed for treating food and medical supplies to inhibit growth of bacteria, viruses, fungi, and insects, and for polymerization of plastics and rubber. They take the place of thermal... 

Treatment of solid wood over the years for increased utility included many chemical systems that affected the cell wall and filled the void spaces in the wood. Some of these treatments found commercial applications, while some remain laboratory curiosities. A brief description of the earlier treatments is given for heat-stabilized wood, phenol-formaldehyde-treated veneers, bulking of the cell wall with polyethylene glycol, ozone gas-phase treatment, ammonia liquid- and gas-phase treatment, and p- and y-radiation. Many of these treatments led to commercial products, such as Staybwood, Staypak, Im-preg, and Compreg. This chapter is concerned primarily with wood-polymer composites using vinyl monomers. Generally, wood-polymers imply bulk polymerization of a vinyl-type monomer in the void spaces of solid wood. 

In addition, five radioactive isotopes of lithium have been produced. A radioactive isotope is one that breaks apart and gives off some form of radiation. Radioactive isotopes are produced when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive. None of these isotopes has any important commercial application. 

Fifty years of research and development works in polymer radiation Chemistry has led to a number of commercial applications as mentioned very briefly in the Introduction section. Application of ionizing radiation to polymeric materials still remains to be a very active area and the polymer and plastics industry is constantly benefiting from the innovations and fruitful results obtained from the R D works of researchers from all over the world. In the remaining part of this report a modest effort will be made to provide a survey of current developments in applied radiation chemistry of polymers and emerging new applications. 

In many cases the use of pigments is not a convenient way to prevent the absorption of damaging radiation by polymers. However, substances that are transparent in the visible region but have a high absorption coefficient in the ultraviolet can be used as filters for that part of the solar spectrum which is responsible for the deterioration of most polymers. Although many organic compounds have a suitable absorption spectrum for that purpose only very few can be used as ultraviolet absorbers a severe restriction is that they should be photochemically stable, otherwise the stabilization effect will not be durable and sensitization may occur. Ultraviolet absorbers that have found commercial application belong to five main families. 

A vacuum of from 4-6 torr (0.53 - 0.80 kPa) is common, and the heat loss by the subliming water usually will keep the material frozen. During small-scale laboratory operations the sample holders are left in the open air, but in large-scale commercial applications, heat must be applied to provide the sublimation energy at the rate Just below that required to keep the material frozen. To sublime 1 g of ice at 0 C requires 666 calories (2.78 kJ). This heat is provided by warm-water trays placed under the sample trays, by radiation from heated walls surrounding the sample trays, or by microwave warming. Sublimation from commercial warm water-heated trays occurs at the rate of 0.1-1.0 kg HjO/hr/m. Few systems are cooled below -30 °F, because the vapor pressure is then too low for rapid sublimation. 

In another commercial application of free-radical polymerization, polymerizations may be carried out in industrial coatings in the presence of air to yield a variety of coatings and structures of commercial import. This development is possible. In part, because certain vinyl monomers, particularly the acrylates, are less sensitive to retardation by oxygen compared with other monomers. It is therefore possible to produce radiation-cured coatings. UV-cured printing inks and the photopolymers are important in imaging for printing, photoresist, and related applications. 

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