It was confirmed that photodegradation of diene polymers in solutions is accelerated by the addition of quinones or benzophenone as a sensitizer. The viscosities of the polymer solutions were markedly lowered by the degradation with UV-irradiation when the sensitizer was added. Especially, high promotion effects on the degradation of diene polymers were observed by the addition of polyaromatic quinone, such as anthraquinone. The decrease in the solution viscosities, along with FT-IR and 'H-NMR

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... f the irradiated polymers, indicates that the degradation of the diene polymers proceeds through the auto-oxidation mechanism. It is inferred that the effects of quinone groups on the diene polymer degradation result from hydrogen abstraction by quinone groups in excited state.