Synergistic Effect of Graphene Nanoplatelets and Multiwall Carbon Nanotubes Incorporated in PLA Matrix: Nanoindentation of Composites with Improved Mechanical Properties

The synergistic effect of two carbon nanofillers on the mechanical properties of PLA-based nanocomposites was investigated in the present work. Polylactic acid is relatively brittle semi-crystalline polymer which was selected for composite matrix because of its biodegradable properties. It was reinforced with graphene nanoplatelets and multiwall carbon nanotubes by means of melt mixing preparation method. Nanohardness and Young’s modulus of smooth nanocomposite samples received by 3D printing were defined by nanoindentation experiments using Berkovich-type pyramidal nanoindenter. It was found that the compounds, incorporated with both graphene and carbon nanotubes in the polymer structure, exhibit better mechanical performance compared to the nanocomposites loaded with a single carbon nanofiller. Different techniques of sample preparation were applied in order to see the influence of preliminary processing on the nanomechanical properties of composite specimens. X-ray diffraction and Raman spectroscopy were used to study the structural features of the pristine carbon nanomaterials.