Great improvement of low-temperature impact resistance of isotactic polypropylene/ethylene propylene diene monomer rubber blends by traces of carbon nanotubes and β-nucleating agents

In this work, a considerable low-temperature toughness enhancement of isotactic polypropylene (iPP) was achieved by adding 30 wt% ethylene propylene diene monomer rubber (EPDM) as well as traces of β-nucleating agent (β-NAs) and carbon nanotubes (CNTs). The impact strength of the iPP/30 wt% EPDM blend with 0.1 wt% β-NAs reached 6.57 kJ/m² at −20°C, over 2.5 times of pure iPP. A slightly improved impact strength was further found in the β-nucleated iPP/30 wt% EPDM at the presence of 0.05 wt% CNTs. The presence of traces of CNTs, β-NAs, and EPDM displayed synergistic low-temperature toughness reinforcement effect on the iPP blends. The underlying toughening mechanism was attributed to the formation of a great amount of voids and plastic deformation of iPP matrix affected by CNTs, β-NAs, and EPDM. Our work provided a feasible strategy to significantly increase the low-temperature toughness of iPP.