Material propertiesThe nanomechanical behavior of a graphite nanoplatelet/polycarbonate nanocomposite

Quasi-static nanoindentation has been used to characterize the mechanical properties of polycarbonate reinforced with graphite nanoplatelets (GNPs). Poor dispersion or low quality interfacial interactions of GNPs in a polymer matrix can significantly decrease the relative improvement in the material's mechanical strength and stiffness. In this study, the surfaces of GNPs were modified to achieve better dispersion and interfacial interaction between fillers and matrix. The GNP/PC nanocomposite has a heterogeneous microstructure, and the original mechanical properties between filler and matrix have large differences. Using a spatially sensitive probe method leads to measured values of modulus and hardness that correlate with the indentation sampled volume. A grid indentation procedure was performed with variable sampling volumes to provide a statistical measurement of modulus and hardness for the nanocomposite materials. The surface treatment leads to a significant increase in both stiffness and hardness for GNP reinforced composites.