A Comparative Study on Thermomechanical and Rheological Characteristics of Graphite/Polypropylene Nanocomposites: Highlighting the Role of Mixing

摘要

The thermomechanical and rheological properties of various graphite/long-chain branched polypropylene (PP) nanocomposites prepared by different mixing methods have been addressed in the current work. To improve the degree of dispersion of graphite throughout the PP domains, solid-state milling was carried out and followed by low-temperature melt processing in the range of melting point and the crystallization temperature of PP. As a result, the well-dispersed graphite/PP nanocomposites revealed a higher degree of plastic deformation and energy to break in the tensile test; moreover, interestingly, nanocomposites based on branched PP showed a lower zero shear viscosity and lower isothermal crystallization rate. It was speculated that the unexpected decrease in zero shear viscosity arose from the disentanglement of the long-chain branches in particular, when an exfoliated morphology existed within the PP matrix. (C) 2014 Society of Plastics Engineers