To explore the use of chemical methods of analysis in investigating the performance of thermoplastic polyolefins (TPO), the ASTM D08.18 Subcommittee undertook a study to evaluate TPO films of known composition. These specially formulated films with varying amounts of stabilizers were heat-aged for up to 56 days according to ASTM D 6878-03 and then analyzed using dynamic mechanical analysis (DMA), thermogravimetry (TG), and Fourier transform infrared (FTIR) spectroscopy. These techniques were found to be useful in characterizing the effect of heat on the TPO films under study and it is believed that they could be used to evaluate actual TPO membranes. Please note that these are films and not roof membranes. The formulations used for the films could be modified for use in actual membranes.