[en] Amount of remained charge and its stability of polystyrene, polymethylmethacrylate, polyvinlidenefluoride, polyethylene, polyethyleneterephthalate and their polymer blends after irradiation with 5-30 keV electrons were measured. Dependences on acceleration voltage, dose, and thickness of the polymer films, influence of humidity, and effects of addition of positive and negative charge scavengers were examined. The polymers were negatively charged by the irradiation. Decay rate of the charge by electron irradiation is slower than that of triboelectrically charged film. The stability increased with increasing the energy of electrons. The addition of a positive charge scavenger stabilized the electrification. The addition of negative charge scavengers changed the polarity of the electrification. (author)

No abstract available

[en] Gelation of polydimethylsiloxane irradiated with 256 MeV Ar ion was examined. The insoluble residue of the irradiated polydimethylsiloxane was separated with membrane filters. The weight of the insoluble residue is proportional to the number of irradiated ions. This result indicates that gelation occurs in the high local dose region of the ion tracks. A gel string is generated in each ion track. The weight of a gel string increases in proportion to the initial molecular weight (M_n) of polydimethylsiloxane. It arises from an increase in the radius of the gel strings with increasing M_n. The gelation dose decreases with increasing M_n. The region with a dose higher than the gelation dose is found in the ion tracks. The radius of the gel strings estimated using the G-value of crosslinking for low-LET radiation and with an appropriate dose distribution in the ion tracks explains the experimental results well

[en] Gelation of polydimethylsiloxane irradiated with 256 MeV Ar, 306 MeV Ne and 204 MeV C ions was examined. The insoluble residue of the irradiated polydimethylsiloxane was separated with membrane filters. The weight of the insoluble residue was proportional to the number of irradiated ions. This result indicates that gelation occurs in the high local dose region in the ion tracks. A gel string is generated in each ion track. The yield of the insoluble residue depends on the ion beams. The radius of the gel strings estimated using the G-value of crosslinking for low-LET radiation and with appropriate dose distributions in the ion tracks agrees with the experimental results

[en] The free radicals generated from polycrystalline hexane at 77K by photolysis with vacuum-ultraviolet light, sensitized photolysis, and γ-radiolysis were compared with each others using the ESR method. The selectivity of radical formation was found to depend on the excitation method. (author)

[en] In order to extend the application of alanine dosimetry, the behavior of free radicals in solid α-alanine irradiated with γ-rays and with ion beams was studied by electron spin resonance. Stable neutral radicals are produced through the decomposition of originally generated ion radicals in alanine irradiated at 300 K, while at 77 K the ion radicals are stable, and also do not decompose. The rate of the combination reaction of the neutral radicals and of the ion radicals was studied by measuring the saturation behavior of the radical concentration in γ-radiolysis at 300 and at 77 K. The yield of the neutral radicals was compared between 0.5, 1,2 and 3 MeV H⁺, 0.5, 1, and 3 MeV He⁺, 175 MeV Ar⁸⁺ and 460 MeV Ar¹³⁺ ion irradiations. Dependence of the radical yield on the radiation quality is understood more in terms of the rate of the combination reaction between the ion radicals than with that between the neutral radicals, and has to do with high local dose within the ion tracks. (Author)

[en] Radiation-chemical reactions of 9,10-dihydrophenanthrene in cyclohexane solution and tetralin in 3-methylpentane matrix were studied by means of the pulse radiolysis at room temperature and by γ-irradiation at 77 K, respectively, in order to elucidate chemically the inhibition of radiation-induced deterioration of polyolefins due to added hydroaromatic compounds. Observed optical absorption spectra showed that solute compounds efficiently scavenge positive hole and electron to form cation- and anion-radical. Two kinds of neutral radicals (by elimination of H-atom from, and by addition of H-atom to hydroaromatic solutes) were generated secondarily from the ion radicals. No evidence could be obtained for direct scavenging of H atom or solvent radicals by added solutes. The inhibition of radiation-induced deterioration of polyolefins is likely due to positive- and negative-charge scavenging rather than free-radical scavenging

[en] The effect of Ar ion irradiation on the reactivity of crystalline and amorphous quartz to alkali has been examined for clarifying whether radiation from nuclear reactors accelerates the degradation of concrete by inducing alkali-silica reaction of aggregates. Distorted amorphous quartz generated on the surface of quartz by irradiation of a 200 keV Ar ion beam is at least 700 times and 2.5 times more reactive to alkali than crystalline and regular amorphous quartz, respectively. The high reactivity of the distorted amorphous quartz indicates that the degradation of concrete by alkal-silica reaction is possible to be induced by nuclear radiation even the aggregates are inert to alkali before the irradiation. The critical radiation doses for the degradation of aggregates containing crystalline quartz are estimated to be 5 x 10¹⁹ n/cm² for fast neutrons with energy > 0.1 MeV, and 5 x 10¹¹ Gy for beta and gamma rays. They are 1 x 10¹⁹ n/cm² and 0.5 x 10¹¹ Gy, respectively for aggregates containing amorphous quartz. (author)

[en] Effects of ion beam irradiation on α-alanine, adipic acid and polydimethylsiloxane were examined. Stable radicals were generated in the radiolysis of solids of α-alanine and adipic acid by γ-ray, 220 MeV C ions, 350 MeV Ne ions and 175 MeV Ar ions. The G-value decreases in this order. The G-value for adipic acid decreases more than that for α-alanine. The decreases in the G-value are ascribed to high local dose in the ion tracks. Effective G-value of the radicals for γ-irradiations decreases at high doses. The local dose in the ion tracks exceeds those doses, and the G-values for the ion irradiation are hence smaller than the G-value for γ-irradiations. The difference in the dependence of the G-values for α-alanine and adipic acid on the ion beams is due to difference in the dose-yield relationship for radical formation. The high local dose in the ion tracks exceeds the gelation dose of some of polymers. Formation of gel strings of polydimethylsiloxanes generated in heavy ion tracks was observed by atomic force microscopy

No abstract available