Purified, degassed samples of cis- and trans-1,2dichloroethylene were irradiated in glass cells with 48Mev helium ions at energy inputs up to 10/sup 21/ ev/cc. The principal volatile radiolysis products are acetylene, hydrogen chloride, chloroacetylene, vinyl chloride, hydrogen, and dichloroacetylene, in order of decreasing yield. The use of a mass spectrometer in conjunction with gas chromatography made possible the identification of several higher-boiling, or ''polymer,'' products as tetrachloroethane, tetrachlorobutene, and pentachlorobutene isomers. However, about half of the higher-boiling material proved to have too low a vapor pressure (b.p.> 300 deg ) at the highest praticable column temperature for these techniques to yield any clues to its nature. Hence these products were characterized only by yield, average molecular weight, and average composition. The effect on product yields of the variation of certain kinetic parameters --total dose, density of initial excitation, and temperature --was determined in survey experiments. These included irradiation with helium ions at 80 deg and at room temperature, irradiation with electrons of differing energy distribution provided by a microwave linear accelerator and by a Van de Graaff machine and irradiation with Co/sup 60/ gamma rays. There are no significant differences in the radiolytic behavior of the cis- and trans- isomers of 1,2-dichloroethylene, and the nature and yield of radiolysis products are explicable on the basis of a series of free-radical reactions, Primary processes of scission of carbonchlorine bonds and molecular elimination of hydrogen chloride, followed by reactions deduced from the nature of the reactive fragments, presents a self-consistent correlation of the experimental data. The yield of disappearance of monomer is of the order of 15 to 20 molecules per hundred electron volts for both isomers, indicating that chain reactions occur. The relatively short chain length and the structural identification of the polymer products that were isolated are in agreement with the postulate that rather unreactive, long-lived polychloro free radicals are formed in these systems. (auth)
