Polypropylene/clay nanocomposites with different nanoparticles are prepared using a specially designed polymer nanocomposite injection molding compounder with a hyperbolic nozzle. The thermal degradation kinetics is studied by estimating the kinetic parameter, activation energy through ASTM E1641 procedure and by the procedures suggested by ICTAC. The activation energies of PP/MMT and PP/OMHT are increasing from 121 and 147 kJ/mol K, respectively, while PP/OMMT and PP/MICA are rather on a linear or a slightly decreasing trend from 160 and 165 kJ/mol K, respectively, over the extent of conversion. The similar trend can be observed in pre‐exponential factor between the different nanocomposites. The reaction model curve explains the complexity of the degradation over the extent of conversion for different nanocomposites. The optimum working temperature of the different nanocomposites prepared is estimated from the kinetic parameters obtained. The nanocomposites PP/OMMT and PP/MICA can operate for 20,000 h before losing its efficiency at 211 and 209°C, respectively, whereas, PP/MMT and PP/OMHT can operate at 165 and 198°C, respectively. The influence of the different nanoparticles, their physical and chemical characteristics in the improvement of the thermal stability has been explained. POLYM. COMPOS., 2019. © 2019 Society of Plastics Engineers