Photo- and Thermooxidative Degradation of Polyethylene-Polypropylene Blends: Comparison of Oxidation Products

The photo- and thermooxidative degradation of various polyethylene-polypropylene (PE-PP) blends (5-80 wt% polyethylene) in air at 60 and 80°C, respectively, have been studied by Fourier-transform infrared spectroscopy. The oxidized samples were reacted with gaseous NH 3 , SF 4 , and NO for rapid identification and resolution of the various carbonyl species, alcohols, and hydroperoxides. The oxidative degradation results are compared with those of corresponding homopolymers. All the samples gave similar oxidation products but in varying quantities depending upon the composition of the sample. The kinetics of oxidation is presented. The oxidation behavior of PE-PP blends changes gradually from pure PE to isotactic polypropylene. The rate of hydroperoxidation of the blends is an increasing function of the propylene content.