Influence of rare-earth-functionalized carbon nanotubes on thermal and mechanical properties of polytetrafluoroethylene nanocomposites

Abstract

Mixed acid and rare-earth (RE) solution were used as the surface modifiers to functionalize multi-walled carbon nanotubes (CNTs). Fourier transform infrared spectra reveal that the carboxylic groups were induced on the surface of acid-functionalized and RE-functionalized CNTs, and the presence of C–N bond suggests that the ethylenediamine tetraacetic acid molecules were successfully grafted on the surface of RE-functionalized CNTs. Raman analysis indicates that acid-treatment and RE-treatment did not significantly change the structure of pristine CNTs. X-ray photoelectron spectroscopy analysis shows that both acid-treatment and RE-treatment improved the number of carboxylic groups on treated CNTs surfaces compared to pristine CNTs, and RE-treatment is superior to acid-treatment to improve the oxygen to carbon ratio on the CNTs surfaces. Transmission electron microscope and scanning electron microscope observations indicate that RE-functionalized CNTs have better dispersion in solvent and in polytetrafluoroethylene (PTFE) matrix than acid-functionalized CNTs, respectively. Thermal stability analysis and mechanical tests display that RE-functionalized CNTs/PTFE nanocomposite has the highest thermal stability and mechanical properties than acid-functionalized CNTs/PTFE nanocomposite and pristine CNTs/PTFE nanocomposite.