Radiations organic liquids

Shkrob, LA., Sauer, M.C., Jr., Trifunac, A.D. Radiation chemistry of organic liquids saturated hydrocarbons. In Radiation Chemistry Present Status and Future Trends, Studies in Physical and Theoretical Chemistry 87, Jonah, C.D., Rao, B.S.M., Eds. Elsevier Amsterdam, 2001 175 pp. 

These coatings are also employed as solid lubricants in engine components. Refractory materials such as MoS2 and WSe2 are lamellar compounds and provide very effective solid-state lubrication in spacecraft bearings and components used in radiation environments where conventional organic liquid lubricants are not stable (see Lubrication and lubricants). 

A more fruitful approach to the irradiation of pure liquids would appear to be that being undertaken by Schuler (S2) in this country and Chapiro (C2) in France. In these studies solutes (iodine and diphenyl-picrylhydrazyl) are added to organic liquids prior to irradiation and the disappearance of these solutes is taken as a measure of the number of free radicals produced by the radiation. The experimental results using the two scavengers mentioned yield values in good agreement for the number of free radicals produced in the radiolysis of organic liquids. 

Liquids dissolved in liquids similarly may form homogeneous solutions. Some liquids have limited solubility in water. Diethyl ether, CH3CH2OCH2CH3 (an organic liquid), is soluble to the extent of 4 g per 100 g of water at 25°C an excess of the diethyl ether will result in a separation of phases with the less dense organic liquid floating on the water. Some liquids mix in all proportions these liquids are completely miscible. The mixture of commercial antifreeze, ethylene glycol, HOCH2CH2OH, and water, used as a coolant in automobile radiators, is such a solution. 

Rather than approach the answer to this question by reviewing the possible intermediates formed either directly or indirectly by the absorption of high energy radiation in an organic liquid, let us look at some of the experimental data obtained by different techniques in various mono-... 

In general, detailed knowledge of the radiation chemistry of organic liquids Is restricted to the lower alcohols and some hydrocarbons and information on other systems in very sparse. This is one of the reasons why pulse radiolysis in organic solvents has not yet fulfilled its potential for application to the study of general chemical problems, as has been the case for aqueous systems. 

The influence of more than 100 organic media (solvents for the monomer) on radiation grafting of 2,4-dimethyl- and 2-methyI-5-vinylpyridine to cellulose (filter paper of various brands and degrees of grinding) was shown to be associated with two factors, namely cellulose swelling and specific interaction of the organic liquid with the monomer and with cellulose75,76 ... 

Currently, the liquid scintillation counter has been employed not only for the measurement of low energy p emitters, but also for pure P, p-y, and a-emitters and further Cherenkov radiation. The liquid scintillator consists mainly of organic solvent and fluorescent material (i.e. solute), and sometimes a surfactant or other material is added to the solution. The characteristics of the liquid scintillator depend mostly on the sort and amount of these chemicals. The liquid scintillator plays the role of an energy transducer, converting radiation energy into photons. The organic solvent which... 

An important difference between the radiation chemistry of water and of organic liquids is that the concept of the spur (a reasonably well-defined volume in which the formation of the reactive species occurs along the track of the ionizing particle) becomes hazy. The radicals formed in water tend to recombine rather than react with the environment immediately after formation. The volume in which recombination is likely defines the spur. The radical products of irradiated organic liquids, however, are more likely to interact with their immediate environment than to undergo recombination. This is evidenced by the low molecular yields of hydrogen from irradiated organic systems. 

In both scintillator and gas detectors, the absorption of radiation causes excitation and ionization however with the scintillation process, the absorbed energy produces a flash of light, rather than a pulse of current. The principal types of scintillation detectors found in the clinical chemistry laboratory are the sodium iodide crystal scintillation detector and the organic liquid scintillation detector. Because of the crystal detector s relative ease of operation and economy of sample preparation, most clinical laboratory procedures have been developed to measure nucfides, such as which can be counted efficiently in a crystal detector. A liquid scintillation detector is used to measure pure (3-emitters, such as tritium or C. 

All organic liquids, including vinyl monomers, produce free radicals on irradiation. The G value (radicals produced per 100 eV of absorbed radiation energy), which is the radiation yield, depends on their structure and can vary from 0.7, for pure styrene, for example, to an apparent value of 19 for carbon tetrachloride in styrene solution. 

This general type of process has been discussed with respect to the radiation chemistry of aqueous solutions (1, 7, II, 20, 22, 24, 31) organic liquids (9), gas-phase mixtures (29), a model for radiobiological sensitization (I, 6), and with respect to some apparent conflicts between steady-state radiation chemistry and pulse radiolysis (22, 24). In this paper, some examples of electron transfer in pulse radiolysis have been chosen to illustrate various features of this phenomenon. 

Radiation Chemistry of Organic Liquids Saturated Hydrocarbons. 

In addition to sodium iodide crystals, a number of organic scintillators such as stilbene, anthracene, and terphenyl have been used. In crystalline form, these compounds have decay times of 0.01 and O.l ps. Organic liquid scintillators have also been developed and are used to advantage because they exhibit less selfabsorption of radiation than do solids. An example of a liquid scintillator is a solution ofp-terphcnyl in toluene. 

In addition to the separate or combined effects of heat, oxygen, and radiation, polymers may deteriorate due to exposure to water (hydrolysis) or different types of chemical agents. Condensation polymers like nylons, polyesters, and polycarbonates are susceptible to hydrolysis. Structural alteration of some polymers may occur as a result of exposure to different chemical environments. Most thermoplastics in contact with organic liquids and vapors, which ordinarily may not be considered solvents for the polymers, can undergo environmental stress cracking and crazing. This may result in a loss of lifetime performance or mechanical stability and ultimately contribute to premature mechanical failure of the polymer under stress. 

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