Several model HFFR polypropylene compounds were prepared in a twin screw extruder and analysed with TGA to support our working hypothesis and approach. The maximum specific mass loss rate and maximum temperature were used to determine the maximum degradation rate required to determine Tign. Equations 1-4 below were used to determine the critical degradation temperature (Tcr) of the materials that represent Tign. . s) We used the m´´cr value for sustained ignition, reported earlier by Lyon et al . A private communication with Lyon revealed that this value was derived as an average value from MCC measurements of numerous polymers, and the uncertainty associated with using this average value was around 40% Since we were mainly interested in formulations that pass V0 classification, we analysed most of the model formulations that passed such classification. We also investigated a few HFFR model formulations that failed the V0 classification to verify the applicability of our approach.