Toughness Reinforcement in Carbon Nanotube-Filled High Impact Polypropylene Copolymer with β-Nucleating Agent

In this work, carbon nanotubes (CNTs) were introduced into an impact polypropylene copolymer (IPC) with β-nucleating agent to prepare IPC composites just by means of a simple mechanical blending method without any special treatment of the CNTs. The resultant IPC composites demonstrated an impressively improved impact property (97.78% increment of toughness compared to pure IPC). It was found that CNT aggregates were dispersed in the polypropylene homopolymer (hPP) matrix rather than the interface between the dispersed phase and hPP host. At the presence of CNTs, the size of the ethylene-propylene random copolymer elastomer particles in the IPC nanocomposites was decreased as evidenced by scanning electronic microscopy, and moreover, the mobility of molecular chains in the amorphous phase of the hPP matrix and crystalline lamellae was enhanced as confirmed by dynamic mechanical analysis and small-angle X-ray scattering measurement. The selective distribution of CNTs, the decreased size of elastomer particles, and the enhanced mobility of molecular chains of PP amorphous phase were proven to be responsible for the significantly reinforced toughness of the CNT-filled IPC with β-nucleating agent. Our work demonstrated that CNT aggregates were able to impart a remarkable toughness reinforcement to polymers, without the need for nanodispersion of the CNTs.