Hajime Kadoi

Electron spin resonance study on the radiolysis of neopentane in solid phase during electron irradiation

Abstract The radiolysis of neopentane was investigated mainly in the plastic crystal phase by means of esr spectroscopy during electron irradiation. In this phase, neopentyl, tert-butyl and tert-pentyl radicals were observed. The formation and decay rates of these radicals were measured, and the G-values of those radicals and the rate constant of the decay were estimated in the plastic crystal phase. In order to elucidate the mechanism of radical formation, the difference in effect of additives between plastic crystal and normal crystal phases was examined. It was found that the radical formation is greatly affected by electron scavengers such as CCl4 and SF6 in both phases. On the other hand, the well-known selective radical formation from added alkanes in the crystal phase was not observed in the plastic crystal phase. From the effect of the additves, the mechanisms of the radical formation in the radiolysis of neopentane was discussed.

Radiation-Induced Solid-State Polymerization of n-Butylisocyanate at Low Temperature

Abstract An attempt was made to polymerize n-butylisocyanate at low temperatures (-78 to -196[ddot] C) in various (crystalline, glassy, supercooled, and liquid) states. It was found that the polymerization of n-butylisocyanate occurs in the supercooled state, but not in the crystalline and liquid states. It was possible to obtain a polymer when the monomer was irradiated in the glassy state at -196[ddot] C. However, it was confirmed that the polymerization does not take place under irradiation at that temperature, but that postpolymerization proceeds during the warming. The effect of additives shows that the postpolymerization of n-butylisocyanate may proceed via an anionic mechanism.