Decomposition of Synthetic Polymers Induced by Hydrogen Atoms

Abstract

In relation to the coal liquefaction, the reaction between hydrogen atoms and synthetic polymers has been studied.
Polystyrene, poly (thio-1, 4-phenylene), poly(methyl methacrylate) and poly[oxy(2, 6-dimethyl1, 4-phenylene)], of which thermal degradation behavior was already known, were subjected to the reaction with hydrogen atoms at temperature ranging from 25 to 300°C and under 133 Pa, using a hydrogen discharge flow apparatus (Fig.1).
Hydrogen atom irradiation caused degradation of polymers more effectively than heat treatment by a factor of 2 to 100 (Figs.2, 3). On heat treatment, polymers gave oligomers mainly composed of dimers, trimers and monomer (Tables 1, 2 and Figs.5, 6). On hydrogen atom irradiation, dagradation products comprised hydrogenated and/or hydrocracked monomers in addition to thermally degraded products (Figs.5, 6, 7). Structural feature of residual polymers was essentially similar to the original one.
These results suggested that hydrogen atoms enhanced the initiation steps of degradation reactions to give macroradicals by hydrogen abstraction from the polymers and/or selective addition to heteroatoms of the polymers.