Exploring temperature dependence of the toughening behavior of β-nucleated impact polypropylene copolymer

In this study, the effects of α- and β-nucleating agents (α-NA and β-NA) on the toughening behavior of impact polypropylene copolymer were ascertained with respect to three test temperatures (23, 0 and −15 °C). The addition of α-NA impacted the toughness slightly for all test temperatures. However, the tendency of impact strength vs. β-NA content at 0 °C significantly differs from that of the other two temperatures. Importantly, a close correlation between toughness at 0 °C and chain mobility of the amorphous portion has been well revealed for the first time by achieving a linearly fitting between impact strength at 0 °C and β-relaxation peak intensity in DMA spectrum. A comparative investigation between the situations containing α-NA or β-NA offers new insights into the physical origin of the toughening behavior for a multiphase multicomponent polyolefin system. The chain mobility of matrix amorphous portion plays a dominant role on toughening.