Styrenics thermoplastic vulcanizates (STPV) were developed for long-term high temperature applications. These STPVs consist of polypropylene as the continuous phase and a crosslinked hydrogenated styrenic block copolymer (SEBS) as the dispersed phase. The present study compared the single-step process and two-step process in an industrial scale twin-screw extruder. The results indicate that the tensile strength, hardness and density of the dynamically cross-linked blend for both of the two methods have not changed significantly. Heat aging study was (85 °C for 168 h) on the SEBS/PP blend was prepared via both of the single-step and two-step processes. It was found that the results were improved by two-step process. The compression set increase (about 7%) in different conditions (120 °C for 70 h, 100 °C for 22 h) on the SEBS/PP blend in the two-step process. The two-step process led to increasing tensile stress at 20% extension (from 2.7 to 3.3 MPa). Both of elongation at break and melt flow index (190 °C, 5 kg, 10 min) decreased ((from 897% to 309% and from 6.8 to 3.7 respectively).

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