Abstract: The thermal oxygen aging mechanism of polypropylene（PP）was studied using the methods of melt flow rate and infrared spectroscopy. It was found that the thermal oxidative aging degradation rate of PP obeys an exponential function, and the fitting degree was high. This suggested that before thermal oxygen aging degradation, PP needs some additional energy. When the energy was accumulated to a certain degree, the “induction period” appeared and PP began to degrade and the rate of degradation would be accelerated.

Key words: polypropylene, Carbonyl, melt flow rate, Aging mechanism, infrared spectroscopy