ABSTRACT
The results of oxidation of melt-prepared PP films with small spherulites (curves 1 and 3) and with large spherulites (curves 2 and 4) (60) are shown in Fig. 9. The latter (large spherulites) were formed under long heating in vacuum. In this case, the recrystallization did not change the crystallinity. The comparison of the curves in Figs. 8 and 9 (in which concentrations are calculated for the sample mass) clearly shows that the three mentioned methods of film preparation result in significantly different pictures. Contrary to the films with a more dynamic phase (see Fig. 8), more stable films possess a shorter stage of autoacceleration after leaving the induction period (see Fig. 9). These films reach the stage of hydroperoxide decay
much faster, and the low value of the concentration maximum, respectively (see curves 3 and 4). In addition, the recrystallization, induced by the prolonged annealing of the films, results in a significant increase of the induction period (see Fig. 9, curves 2 and 4).
