Modified Graphene Sheets/Polyimide Composites Prepared Using In-Situ Polymerization

In this study, the electrical conductivity and thermal properties of polyimide (PI) were improved using commercially available graphene nanoplatelets (GNPs). The GNPs were first oxidized at a high temperature, forming oxidized GNPs (u-GNPs), and then modified with nitric acid to form nitric acid GNPs or with sulfuric acid and nitric acid to form mixed-acid GNPs (m-GNPS). The m-GNPs were then modified with a coupling agent (3-aminopropyltriethoxysilane) to improve their dispersion and thermal stability in the PI matrix. The GNPs were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, ultraviolet visible spectroscopy, and Raman spectroscopy, which confirmed the successful preparation of the modified GNPs. After acid modification, the morphology of the o-GNPs began to generate defectson the surface. At a loading of 2 wt% silane-modified GNPs, the surface resistivity of the PI decreased from 5.92 x 10(14) Omega/cm(2) (pure PI) to 3.25 x 10(7) Omega/cm(2), meeting the electrostatic charge criterion. The results indicated that GNPs can improve the thermal stability, electrical properties, and mechanical properties of PI composites.