Influence of copolymer composition and curing on toughness of isotactic polypropene blended together with metallocene-EPDM and ethene/propene/vinylcyclohexane terpolymers

Ethene/propene terpolymers containing either 1-vinyleylohexene-4 (VCHen) or vinyleyclohexane (VCHan) as termonomer component were prepared using MAO-a ctivated rac-Me2Si(2-MeBenz[e]Ind)(2)ZrCl2 (MBI). Propene content was varie d between 26 and 72 wt-% with less than 1 mol-% termonomer incorporation. B lends containing 85 vol.-% isotactic polypropene (i-PP) and 15 vol.-% of th e two EP terpolymer families were prepared by melt-compounding in a twin-sc rew kneader at 200 degreesC to examine the role of sulfur-mediated crosslin king of the unsaturated EPDM terpolymer phase in comparison to the correspo nding blends containing non-crosslinked saturated EP/VCHan terpolymers. The observed glass temperature (T-g) depression of the T-g of EP(D)M phases wi th respect to the T-g of the corresponding bulk EP(D)M was attributed to th e presence of thermally induced stresses in both blend systems. Blends of i -PP with crosslinked EPDM showed smaller T-g depression with respect to tho se of iPP/EPM blends containing non-crosslinked EP and EPM dispersed phases . Morphology differences were detected for i-PP/EPM and dynamically vulcani zed i-PP/EPDM blends by means of atomic force microscopy (AFM). The crossli nked i-PP/EPDM blends exhibited significantly improved low temperature toug hness as compared to the corresponding non-crosslinked i-PP/EPM blends. Cur ing of the EPDM elastomer phase in i-PP/EPDM (85 vol.-%/15 vol.-%) blends a fforded significantly improved toughness/stiffness balance and a wider toug hness window with respect to the corresponding i-PP/EPM and i-PP/EP blends without sulfur-cured rubber phases.