Due to the strong hydrophobic and van der Waals interactions between individual carbon nanotubes (CNTs), these particles easily aggregate with themselves. When CNTs were introduced into a polymer matrix as a filler, aggregations formed that can adversely affect the mechanical and thermal properties of polymer/CNTs composites. To prevent aggregation, covalent functionalizations via chemical treatments using H₂SO₄/HNO₃, H₂O₂/H₂O and a silane coupling agent(STX)-glycidoxypropyltrimethoxysilane, GPTMS) on the CNTs were chosen in this study. Moreover, the effect of the functional groups on the solubility of CNTs in tetrahydrofuran (THF) was investigated. The surface-modified multi-walled carbon nanotubes (MWCNTs) were also characterized and compared with pristine MWCNTs using several techniques. Morphology changes in surfacemodified MWCNTs were observed by Raman spectroscopy and Field-Emission Scanning Electron Microscopy (FE-SEM) images. Qualitative analyses of the functional groups on the surface-modified MWCNTs were performed by Fourier Transform Infrared Spectroscopy (FT-IR). Additionally, quantitative analyses were performed by X-Ray Photoelectron Spectroscopy (XPS), Energy Dispersive Spectroscopy (EDS), a titration method and Thermogravimetric analysis (TGA).
Keywords: Carbon Nanotubes (CNTs); Covalent Functionalization; Surface Modification Process; Qualitiative Analysis; Quantitiative Analysis.