The chemical and physical property changes produced in polypropylene samples by \u3b3-irradiation in air have been measured for a range of potential stabilizers. Impact properties of post-irradiation aged samples were compared with the yields of tertiary and secondary hydroperoxides, peroxyl radicals and ketones. Some additives markedly increased the initial rate of peroxyl radical decay, but this effect did not correlate with subsequent stability. Retention of impact strength was found for additives which minimized the initial formation of hydroperoxides and ketonic, backbone scission products. A piperidyl additive gave good protection but was especially effective when used in combination with some benzophenone derivatives. The latter were largely ineffective radiation stabilizers when used alone. None of the stabilizers appeared to reduce the initial yield of peroxyl radicals produced in the \u3b3-irradiated polymer and the piperidyl compound was only converted to its nitroxide during the post-irradiation period.Peer reviewed: YesNRC publication: Ye
