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

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 (Tg) 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., Δtg. Results show two conditions are required to improve the ductility of the low‐molecular weight propylene homopolymer: ΔTg must be ≥ 3°C and ≥ 30 wt% EPR must be blended with the homopolymer.

Tensile elongation of high‐fluid polypropylene/ethylene–propylene rubber blends: Dependence on molecular weight of the components and propylene content of the rubber

“…This agrees well with Nomura and coworker's data that the elongation to rupture of a low-MW PP with an intrinsic viscosity of 0.89 dL/g greatly increased when blended with EPR with propylene content of 62 wt %. 13 The blends of EPR with PP5 with the lowest MW were found to break before their yielding points, and the mechanical properties could not be improved by the addition of EPR.…”

“…Notably, the tensile deformation of low-MW PP toughened by rubber was studied by Nomura and colleagues only. [13][14][15] They showed that the addition of EPR of more than 30 wt % is one of the requirements for the manufacture of ductile low-MW PP. However, the effect of the rubber on the elongation and the mechanism of the deformation have not been clarified sufficiently.…”

Fracture characteristics and deformation behavior of heterophasic ethylene–propylene copolymers as a function of the dispersed phase composition

“…The fracture toughness of both mechanical and reactor PP/EPC blends has been the subject of extensive studies, focused to the effect of matrix and dispersed phase molecular weight, particle size, interparticle distance and volume fraction of the EPC [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. Nevertheless, the influence of the dispersed phase composition on the impact performance of such blends is only scarcely reported [39,40] or accounted by some authors as negligible [41,42].…”

Fractionation and characterization of an ethylene–propylene copolymer produced with a MgCl2/SiO2/TiCl4/diester‐type ziegler–natta catalyst

“…It is commonly accepted that Ziegler-Natta catalysts have a plurality of active species. [4][5][6][7] During copolymerization, because these active species have different reactivity ratios toward ethylene and propylene and different stabilities, the incorporation ratio of the two comonomers in the propagating chain varies with time. Thus, copolymers prepared by heterogeneous catalysts often exhibit both intermolecular and intramolecular compositional heterogeneity, and the produced copolymers are actually mixtures and contain a range of components with different composition and sequence distributions.…”