Characterization of gamma-stabilized PP with blends of hindered amine/phenolic stabilizers

In this work, the effect of γ radiation at doses of 25 and 50 kGy on polypropylene (PP) stabilized with a binary system of antioxidants of the phenol-hindered amine type (BHT-Chimassorb 994) at different compositions (0.1/0.2, 0.1/0.5, 0.1/0.8) was studied. The results showed that the carbonyl index (Ic) of the stabilized samples drastically decreases when compared to that of the pure PP sample. Nonetheless, the Ic values of the different stabilized samples were very similar after irradiation. On the other hand, the average molecular weights (Mw and Mn) and melt flow index (MFI) values decrease in all the samples after irradiation. This effect is less pronounced in PP with 0.1/0.8 of the binary blend of antioxidants. The melting and crystallization peak temperatures and the crystallinity degree remained almost unchanged and the tensile properties such as Young's modulus and tensile strength did not vary either, except for the elongation at break, which decreases in less proportion in those blends of PP with the antioxidants, independently of the absorbed dose