Peroxide dynamically vulcanized high molecular weight hydrogenatedstyrenics block copolymer (SEBS)/polypropylene based TPV by one-stepand second-step processes via reactive extrusion

Styrenics thermoplastic vulcanizates (STPV) were developed for long-term high temperatureapplications. These STPVs consist of polypropylene as the continuous phase and a crosslinkedhydrogenated styrenic block copolymer (SEBS) as the dispersed phase. The present study comparedthe single-step process and two-step process in an industrial scale twin-screw extruder. The resultsindicate that the tensile strength, hardness and density of the dynamically cross-linked blend for bothof the two methods have not changed significantly. Heat aging study was (۸۵ °C for ۱۶۸ h) o n theSEBS/PP blend was prepared via both of the single-step and two-step processes. It was found thatthe results were improved by two-step process. The compression set increase (about ۷%) in differentconditions (۱۲۰ °C for ۷۰ h, ۱۰۰ °C for ۲۲ h) on the SEBS/PP blend in the two-step process. Thetwo-step process led to increasing tensile stress at ۲۰% extension (from ۲.۷ to ۳.۳ MPa). Both ofelongation at break and melt flow index (۱۹۰ °C, ۵ kg, ۱۰ min) decreased ((from ۸۹۷% to ۳۰۹% andfrom ۶.۸ to ۳.۷ respectively).

کلیدواژه ها:

styrenics thermoplastic vulcanizates ، polypropylene ، single-step ، two-step ، properties