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The effects of additives on the stability of y-irradiated polypropylene film have been examined, both during irradiation and after prolonged post-irradiation reaction up to the embrittlement point. Additives were drawn from the tetramethylpiperidine family and compared with a conventional blocked phenol. Oxidation products from the polymer were determined by FTIR spectroscopy coupled with chemical derivatization. Polymer physical degradation was measured by an instrumented bend test. Although the stabilizers had very little effect on the radical products or oxidation products measured immediately after y-irradiation, very different oxidation product levels and distributions were found at the onset of brittle failure. Brittle failure occurred at a very low level of total oxidation products for the well-stabilized samples as compared to the unstabilized samples. Nevertheless ketonic product levels were very similar in all cases and the levels of carboxylic acid and groups appreciably higher for the stabilized samples.

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