Compatibility and tensile behavior of polypropylene/ethylene‐propylene rubber blends

Abstract

Abstract This study clarifies and quantifies factors which increase the ductility of a low‐molecular‐weight propylene homopolymer having an intrinsic viscosity of 0.89 dl/g. The tensile behavior of homopolymer/ethylene‐propylene rubber (EPR) blends was studied from the viewpoint of the associated molecular structure of EPR and its compatibility with the homopolymer. When EPR is “dissolved” in a homopolymer, the glass transition temperature ( T g ) of the amorphous phase of a homopolymer was found to shift to a lower temperature, with homopolymer/EPR compatibility being subsequently evaluated using this shift, i.e., Δ t g . Results show two conditions are required to improve the ductility of the low‐molecular weight propylene homopolymer: Δ T g must be ≥ 3°C and ≥ 30 wt% EPR must be blended with the homopolymer.