Ionizing Radiation physical properties

In the preceding ten chapters of this book, we have described various important chemical and physical changes brought about by the absorption of ionizing radiation in gaseous and condensed media. Wherever possible, we have tried to elucidate the underlying mechanism with a discussion of the properties and reactivities of the intermediate species. However, the book would remain incomplete without discussion of some of the various uses that have been found for radiation-induced reactions in science and industry. 

The radiation-induced method, in the y- or pulse regime [19,20] and, to a certain extent, the photo-induced method [21], provide a particularly powerful means to produce in condensed media, metal, and semiconductor clusters from monomers as precursors, to study their properties and to understand the exotic phenomena which occur whenever a new phase of oligomeric particles is formed in the bulk of a homogeneous mother phase [22-26], phenomena which are therefore rather frequent in physics and chemistry. Unlike a recent review concerning semiconductor clusters [19], the present chapter is specifically focused on metal clusters, induced by ionizing radiation or ultraviolet (UV)-visible photons. 

Tphis paper is concerned with the effect of ionizing radiation on the physical and mechanical properties of copolymers of ethylene with alkyl acrylates, such as ethyl acrylate, butyl acrylate, and 2-ethvlhexyl acrylate (J, 2, 3). These polymers are made by the free radical copolymerization of ethylene under high pressure with alkyl esters of acrylic acid (9). They are more flexible than polyethylene and because of the polar nature of the comonomer, they are more compatible with fillers and with other polymers than is polyethylene. 

Good mechanical and physical properties in a wide temperature range excellent ionizing radiation resistance. 

The polymeric systems are usually composed of a polymer which Imparts the majority of physical properties and actinic additives. In simple systems such as curing films or electron beam resists, the polymer is also the radiation sensitive species. In most cases, the formulations behave simllarily in their response to high energy irradiation. Practically any polymer can be made radiation sensitive by direct exposure to ionizing energies or by formulation with additives such as free radical precursors. Thermally sensitive polymers are also likely to undergo a similar reaction when exposed. 

Different sources of radiation can affect the physical and optical properties of vitreous silica. For instance, a dose of 1 x 1020 neutrons cm-2 has been reported to increase the density of vitreous silica by about 3% (to 2.26g cm-3) [27], Similar increases in density are reported in quartz, tridymite, and cristobalite after comparable irradiation levels. On the other hand, ionizing radiation such as X-rays, y-rays, electrons, or protons carry... 

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