About a quasi-universal character of unstabilised polyethylene thermal oxidation kinetics

Literature values of the induction time t(i) and maximum rate r(S) of oxygen absorption for unstabilised polyethylene samples have been compiled. In Arrhenius plots all of their representative points are close to straight lines of parameters: L-n(t(i0)) approximate to -24.4; E-i approximate to 116 kJ mol(-1) for t(i) and L-n(r(S0)) approximate to -34.2; E-s approximate to 146 kJ mol(-1) for r(s) It can be concluded that there is a quasi-universal behaviour, for the thermal oxidation of polyethylene, irrespective to branching and other structural irregularities or crystallinity. This result is consistent with the hypothesis that radical chain oxidation of PE is essentially initiated by the bimolecular decomposition of hydroperoxides provided that their initial concentration is not lower than 10(-5) mol l(-1) and not higher than 10(-1) mol l(-1). (C) 2003 Elsevier Science Ltd. All rights reserved.