Resistance to high-energy radiation

In many applications, ionizing radiation is used to improve specific properties of polymer materials, to steriUze medical devices, preserve food and to treat waste materials. Electrons and X-rays from particle accelerators or the gamma radiation from cobalt-60 are commonly used. In both cases, the transfer of the radiation energy to absorbing materials is achieved by means of secondary electrons, and the physical and biological effects observed for both t)rpes of radiation sources are very similar. 

Other types of indirect accelerators are vhf resonant cavities and linear induction accelerators, such as travelling wave linacs, standing wave linacs, resonant cavity accelerators and linear induction accelerators [1]. 

The most significant parameters in the irradiation process are absorbed dose distribution, product size, shape, density and throughput rate. The dose absorbed by the irradiated material is defined as the energy absorbed per unit mass in a small volume, at a particular location. The SI unit of doses are gray (Gy) = 1 J/kg, and rad which is 100 times smaller than the gray. 

The thermal effect of radiation absorption (for an absorbed dose of lOkGy, corresponding to 2.4 calories per gram, the water temperature 

The magnitude of the absorbed dose is proportional to the electrons fluency, i.e. the total number of electrons injected per unit area of material. The emitted beam current  

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Aliphatic amine hardeners make it possible to formulate tough epoxide systems, but with limited resistance to high energy radiation. 

Environmental resistance PTFE is practically inert against known elements and compounds. It is attacked only by the alkaline metals in their elementary state, and by chlorine trifluoride and elementary fluorine at high temperatures and pressures. PTFE is insoluble in almost all solvents at temperatures up to about 300 °C. Fluorinated hydrocarbons cause a certain swelling that is, however, reversible some highly fluorinated oils, at temperatures over 300 °C, exercise a certain dissolving effect. Resistance to high-energy radiation is rather poor. 

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