Unsolvated methyl cations, generated by spontaneous -decay of multitritiated methane, have been allowed to react with some aliphatic ethers. The reaction mixtures contain various products, mainly aliphatic ethers, that have been separated by gaschromatography and continuously counted in an ionization chamber. A mechanism involving different reaction channels can provide an explanation of the results.
D3+ ions, produced by deuterium -radiolysis, were allowed to react with gaseous p-tert-butyltoluene. The excited arenium ions formed, if not collisionally stabilized, underwent predominantly dealkylation to form toluene and, to a minor extent, isomerization. The dependence of reaction product yields on the substrate pressure is discussed.
Isoprene polymerizes under the action of γ-radiation from a 60Co source yielding a low molecular weight polyisoprene which remains soluble in the unreacted monomer. The electronic absorption
spectrum of polyisoprene oligomer in isoprene monomer has been explained using squalene, a polyisoprene hexamer, as model
compound. The radiation chemical yield for polyisoprene formation has been estimated from both gravimetric and spectrophotometric
data pertaining the amount of polymer formed. An average G value of 35 molecules/100 eV has been determined suggesting that the polymerization mechanism involves free radicals. The
chemical structure of the resulting polyisoprene radio-oligomer has been determined by FT-IR spectroscopy and found identical
to that of a reference polyisoprene sample prepared by a chemically-initiated free radical polymerization process. The structure
determination by FT-IR spectroscopy has been reported in detail.
Authors:F. Cataldo, E. Lilla, O. Ursini, and G. Angelini
C60 fullerene was radiolyzed in toluene solution both in presence of air and in vacuum at four different radiation doses 12,
24, 36, 48 and 96 kGy. Clear evidences of the addition of benzyl radicals to the fullerene cage derive from FT-IR and C13-NMR spectra of the reaction product. In presence of air the interference of oxygen is evident in the FT-IR spectra and from
the elemental analysis. A detailed analysis of the kinetics of the multiple addition of benzyl radicals to the fullerene cage
was made spectrophotometrically with the determination of the addition rate constants at the each addition step and the average
number of benzyl groups added to the fullerene cage as function of the radiation dose.
Authors:F. Cataldo, O. Ursini, E. Lilla, and G. Angelini
Gelatin, the low molecular weight collagen derivative from porcine skin was transformed into a stable permanent hydrogel by
γ-radiation. A series of samples with 3% gelatin solution in water were irradiated at doses of 12, 25, 50, 100, 150, 200 kGy
at room temperature in the absence of air with a dose rate of 2.2 kGy/h. At low dose gelatin hydrogels incorporating all the
available water were obtained. At higher doses above 50 kGy, the gelatin hydrogel samples show a curious shrinking phenomenon
due to the relatively high crosslinking density level achieved, so part of the available water is squeezed out from the gel
cage. The gelatin hydrogel samples were studied by mass fractionation analysis, by spectrophotometric and polarimetric analysis.
Further characterization was made by FT-IR spectroscopy and by thermal analysis (DSC, DTA and TGA) of the dried gelatin samples
after irradiation in comparison to a reference untreated sample.