Resin radiation-damaged

The mechanisms of radiation damage and effects of hardeners were studied recently by pulse radiolysis [89], The epoxy resins require a relatively large amount of curing agents (hardeners), most of them are aromatic and aliphatic amines such as diamino diphenyl methane or triethylene tetramine. On the basis of the emission spectra and kinetic behavior of excited states observed, the radiation resistance of aromatic and aliphatic amine curing epoxy resin was explained by internal radiation protection effects due to energy transfer. 

Radiation damage to the resin is more severe in the loading column. If the actinides load up to the resin capacity (about 2... 

In practice, much higher flow rates and somewhat larger resin particles were usually used. Flow velocities were typically in the range of 5 to 25 ml cm 2 min 1 cm min 1 for elution and up to 50 cm min 1 for loading. In contrast, conventional ion exchange separations of trivalent actinides commonly used 0.1 to 0.2 cm min 1. Thus, the time required for the separation was reduced by factors of 10 to 100, with a comparable reduction in radiation damage. 

Wheelwright has developed a cation exchange separation of americium from the lanthanides using DTPA as eluent (24). Nakamura et al. have improved the process by incorporating a porous-type cation-exchange resin and a pressurized column (25). The effect of radiation damage of the resin has been also investigated on operation modes. 

Phenylbenzofuran (282) was used to protect polyphenylene ether resins against damage from UV radiation <87USP4665ii2>. As a nucleating agent, benzofuran-2-carboxylic acid (283) was found to improve the properties of an ethylene/4-methyl-l-pentene copolymer <84JAP(K)59197446). 

The ultimate solution to the insulation problem is probably the use of ceramic insulation that would be completely radiation resistant. However, considerably more development work will be required before this type of insulation becomes usable. There are data available which indicate that silicone-resin-bonded reconstituted mica (Isomica, trademark name of Mica Insulator Co.) may have better radiation resistance than Fiberglas and silicone varnish. If this material proves to be better from a radiation-damage standpoint, it can probably be incorporated into a pump at a much earlier date than the ceramic insulation. 

Chemical fixation for transmission electron microscopy prepares cells for the preservation of damage due to subsequent washing with aqueous solvents, dehydration with organic solvents such as ethanol or acetone, embedding in plastic resins, polymerization of the resins by heat, exothermic catalysts, or ultraviolet radiation, and imaging with high-energy electron beams in an electron microscope. 

Natural weathering such as wind and rain erosion can eventually lead to failure of protective coatings of composites including paints, and the underlying fiber -resin material, if left exposed, is then vulnerable to continued weathering [29]. Water penetration and UV radiation are other factors damaging composites. 

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