Effect of Hydrogen Atmosphere on Radiation- Induced Gas Evolution from Polyisoprene

Polyisoprene was irradiated in hydrogen atmosphere by ⁶⁰Co γ-rays. The evolved gases were methane, ethane, ethylene, propane, propylene and butane. With respect to saturated hydrocarbons, the yields increased with increasing pressure of hydrogen. On the contrary, the yields of unsaturated hydrocarbons decreased. The G-value of methane in hydrogen of 1 MPa was about four times larger than that in vacuum for irradiation of cis-polyisoprene (Cis) at 160 kGy. The gas evolution from trans-isomer (Trans) was about the same as that from Cis. The yields of gases from gloves made of natural rubber were smaller than those from Cis or Trans.     

Effect of Gamma-Irradiation on Cation Exchange Resin

Several forms of cation exchange resins with different crosslinkages have bsen subjected to ⁶⁰Co γ-radiation, in wet or dry state and the effects of such variables as adsorbed ionic species, crosslinkage of the resin, and the water content in the resin on radiation damage to organic resin have been examined in their relation to γ-radiation dose. The result showed that radiation caused marked changes in the chemical and physical properties of the resin, and phenomena such as de-crosslinking, loss of strong-acid capacity, formation of a functional group composed of a weak-acid exchange group were observed. The degree of such degradation phenomena was not affected by adsorbed ions when their valency states were kept unchanged during irradiation, but when the adsorbed ions were reduced during exposure, the extent of degradation was found inhibited to a significant extent. It may be concluded from the results that the decomposition of the cation exchange resin is mainly initiated by reaction with the resin produced by radiation-formed reducing species, i.e., H atoms. A mechanism of resin degradation is also proposed.     

Enrichment of the Uranium Isotopes by Electromigration in a Cation Exchange Membrane

The γ-radiolysis of water subjected to gas bubbling has been studied using a specially desinged gasloop. During the irradiation, N₂ gas was bubbled from the bottom of the irradiation vessel. As the N₂ gas feed rate was raised, the apparent G(H₂) value increased in keeping therewith, from 5 × l0^?3 to 0.26. However in the presence of a sufficient amount of O₂ or H₂O₂, G(H₂) was raised almost to the level of the molecular yield. With reasonable assumptions, it could be concluded that 3～5 × 10^?6 mol/l of H₂O₂ was sufficient to reduce the back reaction of molecular products to less than 10% under the present experimental conditions. It was also found that the G(H₂) value increased with CH₃OH concentration roughly in proportion to log(CH₃OH), and reached 3.1 with 0.1 mol/l CH₃OH.     

Effect of Gamma Irradiation on Celluloid Film and Related Influence on the Registration of Alpha Tracks

Celluloid film, used as for α-track detection for its being one of the most sensitive solid state track detectors, was irradiated up to 3.5 × 10⁷ rad by ⁶⁰Co γ-rays. The radiation damage was examined by weighing a piece of the film before and after etching with sodium hydroxide solution under various conditions. Six molar sodium hydroxide solution at 50°C was found to be the most suitable etching solution for this irradiated celluloid film. On measuring the optical density, it was seen that the absorption curve for UV light shifted to the longer wavelength side accompanying an increase of absorption dose of γ-ray energy on the film. Both the gravimetric and the optical methods of determining radiation damage indicated its dependence on the γ-ray absorption dose. The sensitivity of α-track registration was also estimated by examining the appearance of α-track under the optical microscope according to etching time. The critical energy of the celluloid film for the registration of α-tracks decreased with the absorption dose of γ-rays.