γ‐radiolysis of ketone polymers. III. Copolymers of ethylene and carbon monoxide

Abstract

AbstractThe γ‐radiolysis of copolymers of ethylene and carbon monoxide (CO‐PE) containing 0–9 wt‐% of CO has been studied in the solid phase under vacuum with respect to hydrogen production, scission, and crosslinking. In this regard, the introduction of carbonyl groups into polyethylene increased both the scission and crosslinking efficiency. However, a theoretical statistical treatment for random scission and crosslinking, which was used to calculate G(s) and G(x) yields, predicted gelation with irradiation dose; this was confirmed experimentally. The increased G(x) values are attributed to the localization of absorbed energy in the carbonyl group arising from preferential trapping of thermalized secondary electrons. A stoichiometric balance is shown to be consistent with the reduction of one carbonyl group to a secondary alcohol per excess crosslink observed. The G(H2) yield is reduced by the presence of ketone groups to a level which is in close agreement with the yield obtained for the model ketone 12‐tricosanone. This quenching of H2 production is explained by intramolecular electronic energy transfer along the chain to the carbonyl group with concomitant intermolecular charge transfer between neighboring molecules.