Styrenic thermoplastic vulcanizates (STPV) consisting of polypropylene (PP) and linear low density polyethylene (LLDPE) as a continuous phase and a crosslinked hydrogenated styrene block copolymer (SEBS) as a dispersed phase were prepared in an industrial scale using a corotating twin-screw extruder. Morphological study of the TPVs was carried out using a scanning electron microscope (SEM). Rheological study of SEBS blends with different percentages of 2,5-dimethyl-2,5-di(tert-butyl peroxide)hexane (0.5, 1, 2, and 4 wt%) was performed. T90 appeared with 4 w% peroxide, indicating complete curing. Effect of peroxide content (0.5 to 1.2 wt. %) on properties of the TPVs resulted in an increase in tensile strength (from 5.6 to 7.4 MPa) and hardness to a certain extent (74 shore A). On the other hand, mechanical properties such as the elongation at break (from 592% to 284%), melt flow index (MFI) (from 29.6 to 3.14 g/10 min at 190°C, 10 kg) and tear strength (from 35 to 30 kgf/cm) decreased. The compression set did not change much at low temperature (70°C), but decreased at high temperature (120°C) due to higher curing (from 69% to 46%). Thermal aging (at 85°C for 168 hours) was performed on TPVs prepared with different peroxide percentages (0.5 to 1.2 wt. %). It was found that the results of elongation and hardness after aging have the lowest amount using 0.9 wt. % peroxide. However, the tensile strength after aging decreased with increasing the content of peroxide. As a result of increased curing with increasing peroxide content, the melting point of the prepared TPVs disappeared. The results of using triallylcyanurate (TAC) and bismaleimide (BMI) as co-curing agents in peroxide curing indicated that all three cases of tensile strength, hardness and elongation at break (from 897 to 1082%) of the STPV increased with BMI. Also, the dynamic vulcanization results on the properties of SEBS/LLDPE/PP-based TPV showed that the crosslink density and gel content of TPV were close to those of EPDM rubber (fully crosslinked) while exceeding those of TPE (uncrosslinked). Overall, the results showed that the tensile strength and density of the dynamically crosslinked blend did not change significantly under peroxide curing.

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