Thermally reduced graphene/polypropylene nanocomposites: Effects of processing method on thermal, mechanical, and morphological properties

In polymer processing, solvent and melt intercalations compete in cost-to-property improvements. In this study, melt intercalation and solution blending methods are investigated for manufacturing graphene/polyolefin nanocomposites. Thermally reduced graphene (TRG) was synthesized and characterized by X–Ray Diffraction, Transmission Electron Microscopy, and X-Ray Photoelectron Spectroscopy. A two-step extrusion process was used to prepare polypropylene/TRG (PP/TRG) nanocomposites and compared with solution blended composites. The composites were characterized by X-Ray Diffraction, Small Angle X-Ray Scattering, Scanning Electron Microscopy, Differential Scanning Calorimetry, and mechanical properties. Although, PP crystalline structure remained unaltered with the inclusion of TRG and processing route, the morphology and plastic deformation changed drastically in nanocomposites. Furthermore, Small Angle X-Ray Scattering revealed formation of surface graphenic layer in solution-processed PP/TRG responsible for lower property increment consistent with mechanical and thermal properties results. The two-step extrusion led to enhanced homogenous dispersion of TRG; consequently, the melt-processed nanocomposites exhibited better mechanical properties compared with solution-processed nanocomposites.