The deterioration of polypropylene by oxidative degradation

An explanation is presented to account for the deterioration of the mechanical properties at very low concentrations of absorbed oxygen. The induction time as measured by the oxygen absorption technique overestimates the time to failure with respect to the mechanical properties. Furthermore, it is shown that the extrapolation of accelerated aging data as obtained at elevated temperatures should not be carried out below 50°C. Data are presented to show that an anti‐oxidant is one of the major constituents of a stabilizer system against UV radiation, because the oxidative degradation mechanism is involved. A modified oxygen uptake equipment is described which allows the simultaneous determination of the oxygen absorption and the deterioration of the mechanical properties on the same sample.