Similarly to the modification of NR, the modification or functionalization of PP has also been achieved by the grafting of MAH. Many researchers investigated this modification and reported outstanding effects [17,18]. However, no study has been reported concerning the effect of the grafting of MAH onto both NR and PP on the behavior of the resulting modified TPNR, and particularly its dynamic mechanical properties. The importance of such properties rises from the fact that TPE, as for general purpose elastomers, can be used in applications where they are subjected to cyclic stressing which can generate heat. Their inability to tolerate elevated temperatures may pose a limitation on their application. The objective of this work is, therefore, to study the effect of the chemical modification of NR and PP on the dynamic mechanical properties of a 70/30 NR/PP blend. The grafting of MAHwas carried out in a laboratory internal mixer using a peroxide. The effect of the dynamic vulcanization of the resulting blend is also investigated.