Characterisation of solvent-extractable transformation products of high molecular weight hindered phenols in polypropylene subjected to ionising radiation in air or to thermal ageing

A range of transformation products derived from high molecular weight 2,6-di- t-butylphenol-based antioxidants (Irganox 1010, Irganox 1076, and Irganox 1330) present in polypropylene subjected to ionising radiation (electron beam- or gamma-radiation, 50 kGy) in air, has been characterised by linked HPLC-diode array-mass spectrometric techniques. Some of the irradiation-derived transformation products were not detected in related thermally oxidised polymers. Evidence is presented of the formation of a range of reductive cleavage products derived from Irganox 1010, and also of the formation of transformation products derived from Irganox 1076 and Irganox 1330 in which loss of t-butyl groups has occurred.